Main conservation issues in breeding areas in Western Europe
In recent decades, the West European continental breeding population of Black-tailed Godwits, Limosa limosa limosa, has declined in size and range at an alarming rate (4,40). Most studies focus on the Netherlands which harbours approximately 40% of the European breeding population (4,20) and nearly 90% of the East Atlantic Flyway population (62). Low chick survival has been identified as the main driver of the population decline (43). Studies show that chick survival has declined strongly in the last 40 years in western Europe. Over the same time period, survival rates of adult birds have remained more or less the same (21, 24). Reproductive output is currently too low to compensate for adult mortality, which results in declining godwit numbers (4,20,21,23,24,43).
Key factors that negatively influence breeding habitat quality and chick survival (and therefore godwit population trends) are:
Black-tailed Godwits are particularly sensitive to disturbance. Areas with regular disturbance caused by humans are avoided by breeding godwits. Routes regularly used by walkers negatively affected breeding densities up to 500m (2), while roads with heavy traffic reduced populations by 14-44% up to 1500 m (3). Disturbance therefore effectively reduces the breeding habitat available to Godwits.
Black-tailed Godwits prefer breeding in open areas. Areas near any structure that can be used by predators, such as perches (e.g. trees, buildings), are avoided by breeding birds (35,37,63,64). Such structures therefore effectively reduce the breeding habitat available to Godwits.
Low groundwater and soil moisture levels
In their breeding areas, the main prey items of Black-tailed Godwits are earthworms and leatherjackets that are obtained by probing the soil with their bills (7). This is only possible in moist and therefore soft soils. When wet grasslands are drained, soils dry out during the breeding season and food for adults becomes inaccessible. Black-tailed godwits preferentially nest in the wettest parts of their breeding areas (35, 63, 65). High groundwater levels are also important to chicks. Godwit chicks are precocial and, after hatching, have to collect their own food (26, 27). They prefer foraging in medium to tall vegetation (c. 10-30 cm) where most of their arthropod prey is gleaned from the vegetation (10,26). High groundwater levels retard vegetation growth and maintain open vegetation that is accessible to foraging chicks (8, 9,12, 25, 26, 27, 36) regardless of climate change or fertility of the habitat (12).
The intensity of agricultural land-use
More intensive agricultural practices are generally associated with more intensive draining, higher pesticide and fertilizer application rates, earlier seasonal first mowing or grazing date and higher stocking rates and mowing frequencies. Draining and fertilization lead to earlier and denser vegetation growth that is of poor quality to Godwit chicks (12,25). Earlier mowing or grazing results in higher losses of Godwit clutches and chicks (4,12,20,25,34,38,41,42,43,45,47,66), while intensified agricultural use of grasslands in general reduces growth and survival of chicks (69).
Predation is one of the primary causes of mortality of both Black-tailed Godwit eggs and chicks (1,24,28). Eggs and chicks are killed by a wide variety of predators but eggs are mostly predated by nocturnal, mammalian predators and chicks by diurnal, avian predators. Predation has increased over the last few decades, which is possibly due to an increase in predator numbers and the loss of large open areas that generally support low numbers of predators. Moreover, the vulnerability of clutches and chicks to predation is affected by land use; predation rates of clutches (66) and probably chicks (69) are higher in intensively managed grasslands than in wet herb rich fields.
Black-tailed godwits show strong natal philopatry and breeding site tenacity (i.e. tend to return to their place of birth and use same breeding site year after year; (21,67,68). Breeding site tenacity increases with age (67) and possibly nest success (68, but see 67). Consequently, Godwits are relatively inflexible in adjusting their breeding sites to changes in conditions in their breeding habitat (15,16,33). Furthermore, since the 1980s Black-tailed Godwits fail to advance their laying date significantly despite climate change induced spring warming. Because farmers respond to warmer springs by earlier mowing or grazing this results in reduced reproductive output (12, 34).
From this follows that effective conservation of breeding habitat aimed to promote the reproductive success of Black-tailed Godwits requires:
- large open areas with little disturbance
- high ground water levels during breeding and winter
- during the breeding season high heterogeneity in vegetation structure both within and between fields
- no first seasonal mowing dates before the end of the chick rearing period
- no intensive grazing during the breeding season
- restricted use of fertilizers and pesticides
The requirement of large open areas and high groundwater levels suggest conservation initiatives are most efficient if they focus on large key breeding areas
Main conservation issues in breeding areas in Eastern Europe
No information was found on key factors influencing the population dynamics of breeding populations of eastern Europe and the breeding population east of the Ural to central Asia.
Main conservation issues in staging and wintering areas of the West European breeding population
Black-tailed Godwits Limosa limosa limosa breeding in Europe have several migration routes to the overwintering areas. The western breeding population of L. l. limosa winter and/or stage in France, Spain, Portugal, Morocco and West Africa (mainly Senegal and Guinea-Bissau) (5,6,14,18,29,31,44,46,48,61). While Godwits originally wintered mainly in west Africa, currently a significant proportion of the population winters on the Iberian Peninsula. Between August and January peak numbers of Godwits move between different parts of their wintering range. Studies indicate that Godwits, are very flexible during winter and move around in order to find sites which offer good foraging habitat. Movements are governed by the availability of preferred habitat (bare wet soil) which Godwits track as it becomes available in successive periods across their wintering area (6,19,30,32). Rice fields and natural wetlands are the most important feeding grounds during the non-breeding season, with rice kernels in rice fields and invertebrates in wetlands being the major food source (5,11,13,14,29,30). Rice is available at planting time and during and after harvest (December-February) (17,50). Important threats are changes in land use such as the abandonment of traditional rice cultivation systems or large scale irrigation works that destroy . Hunting mortality in the winter range does not seem to be severe enough to substantially influence population dynamics (19,61).
For optimum conservation, policy makers and management should adopt an international approach and:
- focus on providing sufficient foraging habitat at large spatial and temporal scales
- target the continuation of the traditional extensive rice cultivation systems throughout the wintering area
- prevent the substitution of rice by other crops
- avoid efficient harvesting methods that reduce the amount of spilled rice seeds
- avoid better drainage systems that allow farmers to keep their fields dry during winter so stubble can be burned
- encourage early ploughing and facilitate successional ploughing throughout December-February
- provide flooded fields throughout autumn and winter
- provide legal protection in rice-field areas
Main conservation issues in staging and wintering areas of the East European breeding population
Much less is known about the migrations of the East European breeding population in Ukraine, Belarus and Russia (48,49,51,53,60). These birds moult in the Black Sea region, then cross the Mediterranean and Sahara to winter in tropical Africa from Mali and Lake Chad eastward. The majority of East European Godwits winter in West African inland sites in the Niger inundation zone and around Lake Chad. It is possible that east European Godwits are also to be found among the Godwits wintering in Sudan. Godwits breeding east of the Urals in west and central Asia migrate either to the south-west (Middle East and eastern Africa as far as Zimbabwe, Botswana, Namibia) or south-east (Pakistan, India) (53,48). It is unclear to what extent these populations mix on the breeding grounds.
Godwits from boreal breeding ranges migrate from the end of July until the end of September. During autumn migration large flocks of birds are observed in the Sivash area in the Ukraine. A small number of birds sometimes remain to winter mainly in the region of the Azov-Black Sea seaside, and the Crimea and Danube delta. Scant evidence suggests that birds from the Baltic States migrate south over the territory of the Ukraine. Information on the use of rice and sorghum fields in the Middle East is scarce, but countries like Iran, Iraq, Turkey, Greece and Saudi Arabia have extensive wetlands and coastal regions which are of great interest for bird conservation (50,54,56,57). The staging distribution of Black-tailed Godwit of the eastern breeding population is determined by the abundance of invertebrates and availability due to water level changes induced by weather conditions (39,48,52). Important threats are hunting, human disturbance and raising water levels or lowering water levels by severe draining programs (51,56,58).
For optimum conservation, policy makers and management should adopt an international approach and focus on:
- reducing hunting pressure
- mitigating the deterioration of quality of staging sites caused by changes in wetland hydrology
- increasing knowledge of non-breeding distribution and factors influencing population dynamics and habitat use during the non-breeding season
Teunissen, W., Schekkerman, H., Willems, F. & Majoor, F. 2008. Identifying predators of eggs and chicks of Lapwing Vanellus vanellus and Black-tailed Godwit Limosa limosa in the Netherlands and the importance of predation on wader reproductive output. Ibis, 150 (Suppl. 1): 74-85.
Farmland bird populations in the Netherlands have shown an accelerating decline in recent years, despite extensive conservation efforts including reserves, agri-environment schemes and protection of nests by volunteers. Although agricultural intensification is the main cause underlying these declines, there is a growing concern that the on-going decline of grassland breeding shorebirds in recent years is caused or aggravated by increasing predation. Although predators like Red Fox Vulpes vulpes and Carrion Crow Corvus corone are often accused of causing widespread breeding losses, and calls for management of these species are made, very few field data are available on the incidence of predation on grassland shorebirds and the relative importance of different predators.
Data on egg predators were obtained using temperature loggers and continuous video recordings of 792 clutches in 10 study sites scattered through the Netherlands. Data on chick predators were obtained by radiotagging 297 chicks of Lapwing (7 sites) and 365 of Black-tailed Godwit (12 sites). In total, 22 species were identified as predators of eggs or chicks, of which Red Fox, Common Buzzard Buteo buteo , Grey Heron Ardea cinerea and Stoat Mustela erminea were the most frequent. This study demonstrates that the eggs of grassland waders were primarily eaten by mammals (93%) and their chicks by birds (71%). There was great variation in predation levels and species involved in predation of clutches between sites and years, but less in chick predation. Hence, there was no correlation between predation levels on clutches and those on chicks within the same sites. In sites where more than 50% of clutches were lost to predation, however, nocturnal predators took the larger share. As temporal and spatial variation on a small scale significantly influences predation levels, a site-specific approach based on sound knowledge of the local situation will be more effective in reducing predation on farmland birds than general, country-wide measures. Calculations based on the data indicate that eliminating only one loss factor at a time will often not reverse a local population decline, and provide a strong argument for targeting several locally limiting factors simultaneously instead of focusing on mitigation of predation alone.
Holm, T.E. & Laursen, K. 2010. Experimental disturbance by walkers affects behaviour and territory density of nesting Black-tailed Godwit Limosa limosa. Ibis, 151: 77-87.
In Europe, the number of areas supporting breeding Black-tailed Godwit Limosa limosa has halved over the last 30 years. Although the decline has been primarily attributed to habitat deterioration, human disturbance has also been implicated. A controlled experimental study was conducted at the Danish Special Protection Area (SPA) reserve at Tipperne, comparing bird behaviour and breeding densities from two baseline years with those in 3 years with two experimental levels of disturbance.
Two walked transects were established 700 m apart. Within each of these, a buffer zone of 150 m each side of the transects was marked out with inconspicuous sticks, each zone having an area of 32 ha. The study followed a before-after/control-impact (BACI) design.
Black-tailed Godwits flushed and showed mobbing behaviour significantly more often when disturbed. The duration of simultaneous flights by breeding pairs was greater when disturbed, leaving nests susceptible to predation. Behavioural observations suggested birds were highly sensitive to human disturbance and unlikely to habituate. Disturbance levels of seven walkers/day affected territory densities up to 500 m from routes taken by walkers, causing effective habitat loss to breeding Black-tailed Godwits. The species’ sensitivity to disturbance may help explain why it has disappeared from many areas. Effective conservation of important breeding areas and maintenance of high densities of Black-tailed Godwit and other meadow birds necessitates control of public disturbance to breeding areas.
Reijnen, R., Foppen, R. & Meeuwsen, H. 1996. The effects of traffic on the density of breeding birds in Dutch agricultural grasslands. Biological Conservation, 75: 255-260.
The effect of traffic on the breeding density of grassland birds was studied in 1989 in 15 transects along main roads in The Netherlands. Out of 12 species that could be analysed, 7 showed a reduced density adjacent to the road. There was a strong effect on the summed density of Godwits with an average disturbance distance of 230 m (range 100 to 560 m) from the road at 5000 cars a day and 930 m (range 490 to1690 m) at 50000 cars a day (car speed 120 km/h). At 5000 cars a day most species had an estimated population loss of 12-56% within 100m of roads, but beyond 100 m >10% loss only occurred in black-tailed Godwit Limosa limosa (22% for 0-500 m zone). At 50000 cars a day all species had estimated losses of 12-52% up to 500m while black tailed Godwit and oystercatcher populations were reduced by 14-44% up to 1500 m. Above a threshold value for traffic noise (42 dB(A)) population reductions of Godwits can be expected. In The Netherlands, with a dense network of extremely crowded motorways, traffic should be considered a serious threat to breeding bird populations in grasslands. Greater care should be taken in planning new roads, and it is important to explore how the present effects can be reduced.
Schekkerman, H., Teunissen, W. & Oosterveld, E. 2008. The effect of 'mosaic management' on the demography of black-tailed Godwit Limosa limosa on farmland. Journal of Applied Ecology, 45: 1067-1075.
The largest European population of the Black-tailed Godwit Limosa limosa in The Netherlands, which includes 47% of the European population, has been declining for decades despite conservation measures including agri-environment schemes (AES). Numbers declined from >125000 breeding pairs around 1960 to 62000 in 2004. In a new experimental AES aiming to reverse this decline, collectives of farmers implemented spatially coordinated site-level habitat management (‘mosaic management’) including delayed and staggered mowing of fields, refuge strips and active nest protection. The effectiveness of mosaic management was evaluated by measuring Godwit breeding success in six experimental sites and paired controls. Productivity was higher in mosaics than in controls due to fewer agricultural nest losses. Chick fledging success was poor in both treatments (0.28 +/- 0.05 in AES vs 0.16 +/- 0.05 in Control). Productivity compensated for adult mortality in only one AES site. Although creating chick habitat was a major management goal, the availability of tall grass during the fledging period did not differ between treatments, mainly because rainfall delayed mowing in all sites and study years. However, chick survival increased with the availability of tall grass among sites. Higher chick survival will thus enhance the positive effect of mosaic management in drier years, but sensitivity to weather represents a weakness of the AES design. Available estimates of productivity in Dutch Godwits suggest a strong reduction over the past 20 years and implicate chick survival as the main driver of their decline. Earlier mowing of grassland is the main causal mechanism, but changes in vegetation structure and composition, and increased predation may also have contributed. Demographic rates like breeding success are useful parameters for evaluating effects of management. Mosaic management increases the productivity of black-tailed Godwits, but does not ensure long-term population viability for Godwits. More stringent management prescriptions need to improve both the area and the quality (vegetation structure) of grassland mown late. Management efforts should be concentrated in areas with favourable pre-conditions in order to improve overall effectiveness.
Masero, J.A., Santiago-Quesada, F., Sanchez-Guzman, J.M, Abad-Gómez, J.M & Albano, N.. 2009. Geographical origin, return rates, and movements of the near-threatened black-tailed Godwits Limosa limosa staying at a major stopover site of Iberia. Ardeola 56: 253-258.
Most black-tailed Godwits Limosa limosa en route from West Africa to breeding grounds cross Iberia (Spain and Portugal), but there are fundamental aspects of the stopover ecology of black-tailed Godwits in Iberia which remain unknown. Geographical origin, return rates, and movements of the near-threatened black-tailed Godwits staying at Extremadura's rice fields, a major Iberian stopover site, was investigated. Godwits were captured with mist-nets from January to early March (2005 - 2008), and individually marked with a combination of colour rings and lime flag. Radio tags were used on 24 Godwits. Godwits staging in rice fields feed almost exclusively on rice seeds left after harvest. The length of stay is estimated at 40.4 days for Godwits arriving in mid-January and 17.1 days for arrival in early February. Most black-tailed Godwits staying in Extremadura's rice fields belonged to the declining subspecies limosa, with Extremadura probably being a crucial final take-off site for most of them. In February numbers peaked at approximately 24214 in the Extremadura rice fields. A significant percentage (3-14 %) of subspecies islandica staying in Extremadura was also found. Return rates averaged 35.9 %, and Godwit movements between Iberian stopover sites were documented. The movements of colour-ringed Godwits showed that the main SW Iberian sites probably function as a single functional unit, and therefore the loss of some of these Iberian sites may put at risk the long-term viability of the Western European population of black-tailed Godwit.
Hooijmeijer, J., Bruinzeel, L.W.,Kamp, J.van der, Piersma, T. & Wymenga, E. 2011. Grutto’s onderweg. In: Teunissen, W.A. & Wymenga, E. (eds) 2011. Factoren die van invloed zijn op de ontwikkeling van weidevogelpopulaties. Belangrijke factoren tijdens de trek, de invloed van waterpeil op voedselbeschikbaarheid en graslandstructuur op kuikenoverleving. SOVON onderzoeksrapport 2011/10. SOVON Vogelonderzoek Nederland, Nijmegen. A&W rapport 1532. Bureau Altenburg & Wymenga, Veenwouden. Alterra rapport 2187, Alterra Wageningen. [In Dutch]
Godwits breeding in NW-Europe are known to migrate to western Africa in order to stay over winter. Rice fields in Senegal and Guinée-Bissau used to harbour most Godwits. During the past 20 years the population count in Guinée-Bissau dropped with 78%. To investigate migratory behaviour and habitat use 15 adult female Godwits were tracked from May 2009 onwards using satellite implant transmitters. Due to technical problems only 4 individuals were followed for 1 year, other transmitters varied in lifespan. Successful breeding Godwits left the Netherlands during mid-July, while unsuccessful breeders left a month earlier. Data indicated that approximately 75% (N=8) migrates to Africa while 25% (N=3) overwinters in Europe. Godwits prefer wet rice fields with sparse vegetation. Therefore they migrate during overwintering across western Africa in search of suitable locations. Iberia (Spain and Portugal) formerly classified as a stopover area now proved to be an overwintering area. Individuals varied greatly in migration route, pace of migration, stopovers and overwintering location. Due to the limited number of Godwits tracked sample size should be increased in order to get more generic results.
Kleijn, D., Lammertsma, D. & Müskens, G. 2011. Het belang van waterpeil en bemesting voor de voedselbeschikbaarheid van weidevogels. . In: Teunissen, W.A. & Wymenga, E. (eds) 2011. Factoren die van invloed zijn op de ontwikkeling van weidevogelpopulaties. Belangrijke factoren tijdens de trek, de invloed van waterpeil op voedselbeschikbaarheid en graslandstructuur op kuikenoverleving. SOVON onderzoeksrapport 2011/10. SOVON Vogelonderzoek Nederland, Nijmegen. A&W rapport 1532. Bureau Altenburg & Wymenga, Veenwouden. Alterra rapport 2187, Alterra Wageningen. [In Dutch]
Agricultural intensification is thought to be the main cause of decline in Black-tailed Godwit Limosa Limosa populations in the Netherlands. An important aspect of this intensification is lowering ground water levels in order to advance grass growth and first mowing date on grasslands. Moist soils contain larger numbers and biomass of earthworms, while decreasing ground water levels forces earthworms to migrate deeper into the ground thereby decreasing food availability. The study assessed the effect of ground water level and soil moisture on prey availability (earthworms and Tipulidae larvae) throughout the breeding season in 3 experimental sites. Foraging success of Godwits was assessed by direct observation. The results showed that below a threshold value of 30% for soil moisture habitat quality decreases rapidly causing Godwits to switch from earthworms to alternative prey items like Tipulid larvae. Foraging success of Godwits depended on date and increased with increasing penetration resistance and density of Tipulid larvae. The results indicated that high ground water and soil moisture levels facilitate a stable food supply during the breeding season. Penetration resistance can be used as a simple indicator for soil moisture content. When penetration resistance is above 250 N/cm2 measures should be taken in http://ippp.org/ order to increase soil moisture content. This study showed that this can only be attained by increasing ground water levels during winter. Raising water levels shortly before the breeding season is insufficient. During the breeding season a higher soil moisture content can be achieved by irrigation measures.
Roodbergen, M., Teunissen, W., Schekkerman, H., Majoor, F. & Vriezekolk, M. 2011. Vegetatiestructuur en de groei van gruttokuikens. In: Teunissen, W.A. & Wymenga, E. (eds) 2011. Factoren die van invloed zijn op de ontwikkeling van weidevogelpopulaties. Belangrijke factoren tijdens de trek, de invloed van waterpeil op voedselbeschikbaarheid en graslandstructuur op kuikenoverleving. SOVON onderzoeksrapport 2011/10. SOVON Vogelonderzoek Nederland, Nijmegen. A&W rapport 1532. Bureau Altenburg & Wymenga, Veenwouden. Alterra rapport 2187, Alterra Wageningen. [In Dutch]
This study assessed the effect of 4 different management regimes in enclosures on Black-tailed Godwit chick growth rate. Management regimes were: Nature reserve with high ground water level, Grassland with agri-environment scheme (postponed mowing date), Intensive managed grassland, Regrowth (intensive managed grassland mown 3 weeks before the experiment). Arthropod food availability was assessed using photo eclector traps. Chick growth rate was determined by weight increase. Foraging success was determined by direct observation and diet of chicks was studied by faecal analysis. Chicks grew fastest and had higher foraging success in grasslands with a heterogeneous vegetation structure with a higher abundance of larger prey items (>7mm). Foraging success was positively correlated with high and dense vegetation. The Regrowth management scheme was short in food supply and unable to facilitate sufficient chick growth. Growth rate decreased from 0.3 g/h in Grassland with agri-environment scheme to approximately 50% in Intensive managed grassland, 30% in Nature reserve to a negative growth rate in Regrowth. Management of grasslands therefore should focus on factors controlling the abundance of large prey items. This might be achieved by extensive management (high soil moisture, low mowing frequency, extensive grazing, applying less fertilizer) but more research is needed.
Ausden, M., Sutherland, W.J. & James, R. 2001. The effects of flooding lowland wet grassland on soil macroinvertebrate prey of breeding wading birds. J. Appl. Ecol. 38: 320-338.
Lowland wet grassland in western Europe is often managed for breeding wading such as black-tailed Godwit Limosa limosa. Recommended conservation management often entails introducing winter flooding. Soil macroinvertebrates are important prey for breeding wading birds on lowland wet grassland. This study quantified the response of soil macroinvertebrates to flooding, their ability to survive in flooded grassland, and changes in the abundance and physical availability of soil macroinvertebrates for feeding wading birds as flood water subsides. Unflooded grasslands contained high biomasses of soil macroinvertebrates, comprising mainly Tipulidae larvae and earthworm species that are widespread in pastures. Grasslands with a long history of winter flooding contained much lower biomasses of soil macroinvertebrates, comprising mainly a limited range of semi-aquatic earthworm species. Introducing winter flooding to previously unflooded grassland greatly reduced soil macroinvertebrate biomass, due to earthworms vacating the soil after the onset of flooding. However, when earthworms were artificially confined in flooded soils, most species were capable of surviving periods of at least 120 days continual submergence. Winter flooding also expelled large numbers of overwintering arthropods from the soil. Soil macroinvertebrates were slow to recolonize winter-flooded grassland when it was re-immersed in spring. Consequently, prey biomass for breeding wading birds remained low in areas that had been flooded during the preceding winter. However, winter flooding probably benefited breeding lapwings and redshank by helping keep the sward short and open enough for them to feed in during the latter part of their breeding season. Pools of winter flood water that remained in spring and early summer also provided a source of aquatic invertebrate prey for breeding wading birds.
Beintema A.J., Thissen J.B., Tensen D. & Visser G.H. 1991. Feeding ecology of charadriiform chicks in agricultural grassland. Ardea, 79: 31-44.
Diet of Black-tailed Godwit Limosa limosa, chicks was studied by faecal analysis in 191 samples collected in agricultural grasslands in the Netherlands and 23 samples collected in an enclosure. Black-tailed Godwit chicks hunt for more mobile prey species, higher in the vegetation. Important food items are curculionid beetles, tenthredionid larvae and many flying insects, like Tipulidae, Chironomidae, Bibionidae (especially Dilophus), Empidinae, Dolichopodidae, Muscidae, Scatophagidae and Hymenoptera. To obtain information on food availability, macrofauna was sampled using pitfall traps, sweep nets and an exhauster. In May, the number of arthropods in grassland rapidly increases. In June, arthropod abundance may temporarily decrease. Chicks showed retarded growth from mid-May onwards, before prey abundance peaks. A hypothesis is proposed that from the energetic point of view, chicks cannot grow up on arthropod fauna alone, but have to switch to earthworms, which may become progressively difficult to obtain later in the season.
Estrella S.M. & Masero, J.A. 2010. Prey and Prey Size Selection by the Near-Threatened Black-tailed Godwit Foraging in Non-Tidal Areas during Migration. Waterbirds, 33: 293-299.
Black-tailed Godwits Limosa limosa and other shorebirds rely on non-tidal areas during their annual migration but understanding of stopover ecology in these areas is lacking. In this study field observations, faecal analysis of 42 droppings and prey abundance were combined to investigate diet and prey-size selection by Black-tailed Godwits during fall migration in a salina (salt works or salt ponds) in Cádiz Bay Natural Park, Spain. Although several potential macroinvertebrate prey species were available and abundant, Godwits positively selected one mosquito species (Chironomus salinarius). The larvae and pupae of this prey represented >95% of the total number of items present in droppings during migration (July-September). Consumption of prey of a given size class was not dependent on its abundance. Thus, although larger size-classes of chironomid larvae were not necessarily the most abundant for some months (mean size of available larvae: 8.2 +/- 0.2 mm, 6.4 +/- 0.2 mm and 8.4 +/- 0.2 mm in July, August and September, respectively), they were the ones most frequently consumed by the Godwit (mean size of larvae predated: 9.9 +/- 0.8 mm, 9.2 +/-1.7 mm, and 9.4 +/-1.3 mm in July, August and September, respectively). The role salinas play as stopover foraging areas for Godwits appears dependant not only on the abundance of C. salinarius but also on the abundance of large size-classes of this soft-bodied prey. Conservation and management of salinas that allows the production of high densities of chironomids during the peak of Black-tailed Godwit migration would assist the conservation of this species. For example, it would be possible to reduce the water levels (from 60-40 cm to < 5cm) of some channels and evaporation pans sequentially throughout the post-breeding migration, thereby creating foraging areas with chironomid larvae that otherwise would be not accessible to shorebirds.
Kleijn, D., Schekkerman, H., Dimmers, W.J., van Kats, R.J.M., Melman, T.C.P. & Teunissen, W.A. 2010. Adverse effects of agricultural intensification and climate change on breeding habitat quality of Black-tailed Godwits Limosa l. limosa in the Netherlands. Ibis, 152: 475–486.
Agricultural intensification is one of the main drivers of farmland bird declines, but effects on birds may be confounded with those of climate change. In this study the effects of intensification and climate change on the Black-tailed Godwit Limosa l. limosa was assessed in the Netherlands. Population decline has been linked to poor chick survival which, in turn, has been linked to available foraging habitat. Foraging habitat of the chicks consists of uncut grasslands that provide cover and arthropod prey. Conservation measures such as agri-environment schemes aim to increase the availability of chick foraging habitat but have not yet been successful in halting the decline. Field observations show that since the early 1980s, farmers advanced their first seasonal mowing or grazing date by 15 days, whereas Godwits did not advance their hatching date. Ringing data indicate that between 1945 and 1975 hatching dates advanced by about 2 weeks in parallel with the advancement of median mowing dates. Surprisingly, temperature sums at median mowing and hatching dates suggest that while the agricultural advancement before 1980 was largely due to agricultural intensification, after 1980 it was largely due to climate change. Examining arthropod abundance in a range of differently managed grasslands revealed that chick food abundance was little affected but that food accessibility in intensively used tall swards may be problematic for chicks. The results suggest that, compared with 25 years ago, nowadays a much higher proportion of clutches and chicks are exposed to agricultural activities, that there is little foraging habitat left when chicks hatch and that because of climate change, the vegetation in the remaining foraging habitat is taller and denser and therefore of lower quality. This indicates that for agri-environment schemes to make a difference, they should not only be implemented in a larger percentage of the breeding area than the current maxima of 20–30% but they should also include measures that create more open, accessible swards.
Kloskowski J., Green A.J., Polak M., Bustamante, J.& Krogulec, J. 2009. Complementary use of natural and artificial wetlands by waterbirds wintering in Donãna, south-west Spain. Aquatic Conservation-Marine and Freshwater Ecosystems 19: 815-826.
This study focused on the use made by 12 common waterbirds of the natural seasonal marshes in Donãna National Park (DNP) and the adjacent Veta la Palma fish ponds (VLP) created in the early 1990s. Data used were from aerial and terrestrial surveys collected between October and February during six consecutive winters from 1998/99 to 2003/04. Changes in the distribution of each bird taxon were related to changes in the extent of flooded marshes within DNP. The timing and extent of flooding in DNP was highly variable, but there was a consistent pattern in which black-tailed Godwits concentrated in VLP during dry months and winters but redistributed to DNP as more of it was flooded. Waders feed mainly on invertebrates, and invertebrate biomass in VLP was found to be higher than in DNP. When water levels in DNP were stable over the course of a winter, or controlled for in multivariate models, the numbers of waders at VLP were more stable, and their invertebrate prey became more abundant over time, at least in the winter 2003/4. In this important wetland complex, the value of natural and artificial wetlands for wintering waterbirds are complementary, providing suitable habitat for different species and for different conditions in a highly variable Mediterranean environment. For populations using natural marshlands where water levels are variable, adjacent permanent artificial wetlands may function as a buffer during critical drought periods, preventing or reducing population declines or mortality events. Thus, even if the values of artificial wetlands for independent long-term support of large populations or high species diversity are limited, due attention should be given to their importance as vital habitat components at larger spatial and temporal scales.
Masero, J.A., Santiago-Quesada F., Sánchez-Guzmán, J. M, Villegas, A., Abad-Gómez, J.M., Lopes, R.J., Encarnacao, V, Corbacho, C.& Morán, R. 2011. Long lengths of stay, large numbers, and trends of the Black-tailed Godwit Limosa limosa in rice fields during spring migration. Bird Conservation International 21: 12-24.
Rice fields provide functional wetlands for declining shorebirds around the world, but fundamental aspects of their stopover ecology in rice fields remain unknown. This study estimated the length of stay of Black-tailed Godwits Limosa limosa migrating through rice fields, and shows the international importance of Extremadura’s rice fields (south-west Spain) for this near threatened species. Overall, large numbers of Black-tailed Godwits en route to their breeding grounds had long lengths of stay in the rice fields (34.7 +/- 1.7, 14.4 +/- 2.0 and 8.3 +/- 1.2 days in Godwits radio-tagged in late January(N=10), early February (N=7) and late February(N=7), respectively). Total numbers peaked in February with an average number of 24000 individuals. The long lengths of stay of Godwits in rice fields, together with some aspects of their feeding ecology, suggest that rice fields are suitable staging habitats, and therefore they could play an important role as buffer habitats against the loss or degradation of natural wetlands in north-west Africa. Extremadura’s rice fields supported at least 14% of the declining Western European population of Black-tailed Godwit, and its increasing number in south-west Spain probably reflects a population shift towards the northern part of the winter range.
Ratcliffe, N., Schmitt, S. & Whiffin, M. 2005. Sink or swim? Viability of a black-tailed Godwit population in relation to flooding. Journal of Applied Ecology: 42: 834-843.
Black-tailed Godwits Limosa l. limosa have declined throughout northern Europe because of changing agricultural practices. The relict UK population is now mostly confined to two reserves within flood-defence structures, and numbers have declined at one of these. This study diagnosed the cause of decline and evaluated options for remedial management. Re-nesting models showed that productivity varied among sites and years in relation to flooding patterns. Floods caused breeding failure by forcing Godwits to nest on nearby arable fields where nest and chick survival rates were low. A population model showed that flood-dependent variations in productivity were sufficient to explain the contrasting population trends at the two sites. The relative merits of various options for mitigating the effect of floods were investigated using a combination of hydrological, re-nesting and population models. Models assuming a closed population resulted in numbers of Godwit pairs at the Ouse Washes (eastern England) declining and becoming extirpated within 30 years under current conditions. Some management options improved productivity, population growth and persistence likelihood, but the chances of extirpation were still high and conservation targets would not be met. Models assuming an open population showed that target populations would only be achieved within 30 years if all of the available flood mitigation options were combined. However, habitat creation outside the Ouse Washes resulted in comparable productivity and population growth at a fraction of the cost. Provision of compensatory habitat is likely to be a more parsimonious means of conserving black-tailed Godwits at the Ouse Washes than flood mitigation. However, reliance on the creation of new habitat is a risky strategy as Godwits may continue to use traditional arable fields. An experimental pilot project to create habitat on 44 ha of arable land by the Ouse Washes was initiated in 2002. Although the site supported suitable habitat for breeding waders during a flood in 2004, Godwits chose to nest, and fail, on the arable fields they used during previous flood years.
Schroeder, J., Heckroth, M. & Clemens, T. 2008. Against the trend: increasing numbers of breeding Northern Lapwings Vanellus vanellus and Black-tailed Godwits Limosa limosa limosa on a German Wadden Sea island. Bird Study 55: 100-107.
This study analyses the population development with respect to population development and reproductive success of Black-tailed Godwits from 1977 until 2005 on Wangerooge, a German Wadden Sea island. Godwit numbers increased significantly during the three decades after colonization in 1977. They used a logistic growth model to derive the reproductive output required to explain the past population development without assuming immigration. The values derived by this model were compared with empirical findings of reproductive output of the population. The mean empirical growth rate of the total population (1977-2005) is 1.18 +/- 0.64. The empirical reproductive success of 0.25 ± 0.26 cannot explain the empirical population growth, assuming a realistic survival rate. The results imply that the increase in breeding pairs of Godwits on Wangerooge Island is not due to reproductive output but could be caused by immigration onto the island. If these results can be generalized, they indicate that coastal areas with positive population trends may not produce enough offspring to sustain themselves, let alone act as sources. The assessment of the stability of meadowbird populations in northern Europe changes drastically if it is taken into account that some of the few positive population trends might only be positive due to immigration rather than being self-sustained by reproductive output. Therefore it is of critical importance to understand the dispersal and settlement decisions of Godwits to prevent further population declines in northwest Europe.
Tréca, B. 1994. The diet of Ruffs and Black-tailed Godwits in Senegal. Ostrich 65: 256-263.
Black-tailed Godwit Limosa limosa diet was studied by direct examination of stomach contents in Senegal. The study is based on 207 Godwits killed by hunters in the Senegal delta between 1972 and 1979. Cultivated rice (71%), wild rice (13%) and Cyperacea tubers (12%) were the main diet items. No animal matter was found throughout this study. Rice is available at planting time and during and after harvest (Dec-February). Northward migration to breeding grounds occurs between March and May which is preceded by a weight increase. Godwits in the study area positively selected rice fields and fat deposition for migration was based on a rice diet.
Kamp, J. van der, Kleijn, D., Ndiaye, I.,. Sylla, S.I. & Zwarts L. 2008. Rice farming and Black-tailed Godwits in the Casamance, Senegal. A&W-report 1080/Alterra-report 1614. Alterra, Wageningen / Wetlands International, Dakar / Altenburg & Wymenga ecological consultants, Veenwouden.
Black-tailed Godwits arrive early July in West Africa. Most birds are concentrated in the coastal rice fields in southern Senegal (Casamance) and Guinea-Bissau. Since they consume sown rice and trample seedlings, rice farmers consider the birds as a pest. In total 104 farmers were interviewed on crop damage. Farmers attempt to prevent this damage by growing rice in seedbeds near the village or in the forest and replant the rice later in the season. When the seedbeds are in the rice fields damage is prevented by chasing birds away and shooting. Damage is restricted in time (July-September) and place (small seedbeds within rice fields). A preliminary estimate based on a visit in September 2007 is that about 5% of 9000 Godwits on 66 km2 is annually shot in July-August. Most farmers were convinced that the number of Godwits present on their rice fields increased in recent years while the total population actually showed a decrease of 4%/year. The increase of perceived damage is explained by Godwits nowadays leaving their breeding grounds a month earlier than 20 years ago or immigration due to the loss of a significant feeding area further up north.
Kleijn, D., Kamp, J. van der; Monteiro, H., Ndiaye, I., Wymenga, E. & Zwarts, L. 2010. Black-tailed Godwits in West African winter staging areas : habitat use and hunting-related mortality. Alterra-report 2058, Wageningen.
The decline in reproductive success of Black-tailed Godwits is a main driver of its population decline. The persistence of the Dutch population seems to depend to a large extent on high adult survival and longevity of adult birds. This study examines how sever hunting pressure is in the key overwintering area of the west-African coastal zone and what habitat types are being used. Hunting pressure was assessed by farmer questionnaires. Data on habitat use and Godwit distribution was examined by an aerial and ground survey. Hunting mortality did not seem to be severe enough to substantially influence population dynamics. Between August and January peak numbers of Godwits move between different parts of their wintering range. Movements seem to be governed by availability of preferred habitat (bare wet soil). Godwits track their preferred habitat which becomes available in successive periods across their wintering area. The results suggest that effective conservation probably should target the continuation of the traditional extensive rice cultivation systems throughout the core wintering area, with the rice fields in Guinea-Bissau being of particular importance as this is the only East-Atlantic area that provides suitable habitat in November-December. Important threats to Black-tailed Godwits are changes in land use such as the abandonment of the traditional rice cultivation system or large scale irrigation works. A good second is increased access to rifles and/or cheap ammunition which might increase hunting pressure.
Roodbergen, M. & Klok, C. 2008. Timing of breeding and reproductive output in two Black-Tailed Godwit Limosa limosa populations in The Netherlands. Ardea, 96(2): 219-232.
This study assesses the current population decline of Black-tailed Godwits in The Netherlands, which harbours approximately 40% of the European breeding population. Reproductive parameters were determined in two Dutch breeding populations over the period 2002–2005 and the relationship between reproductive output and timing of breeding was investigated. Annual median laying dates ranged from 14 to 25 April, and median hatching dates from 11 to 28 May. Sites differed in laying dates but not in hatching dates. Daily survival rate of nests was positively correlated to nest age and was affected by year and by the interaction of year and site, but not by laying date. The number of eggs hatching per successful nest also did not depend on laying date. Maximum chick survival (maximum estimate of the number of chicks fledged divided by the number of chicks hatched from the nest) and the probability of raising at least one chick to fledging declined significantly with hatching date, resulting in a decline of reproductive output with laying date. Minimum chick survival correlated negatively with cumulative minimum temperature during the first week after hatching. Duration of rainfall during the chick-raising period did not affect chick survival. The estimates of reproductive output were lower than found in previous studies. Mean reproductive output in the period 2002–2004 at the two study sites was estimated at 0.23–0.59 fledglings per breeding pair. In most years reproductive output was too low to compensate for adult and juvenile mortality. Reproduction rates may be enhanced by facilitating early breeding, taking measures to increase nest success of early breeders, and by promoting chick survival late in the breeding season. This can be achieved by avoiding intensive grazing and other agricultural activities before and during the breeding season. Moreover, chick survival can be improved by delaying mowing and securing spatial heterogeneity, so Godwits find suitable breeding habitat at any time during the breeding season.
Roodbergen,M., Klok, C. & Schekkerman, H. 2008. The ongoing decline of the breeding population of Black-Tailed Godwits Limosa l. limosa in The Netherlands is not explained by changes in adult survival. Ardea, 96(2): 207-218
The Black-tailed Godwit Limosa limosa is a characteristic breeding wader of wet grasslands in The Netherlands which has suffered a strong population decline since the 1960s. Low breeding success has been implicated as the main driver of this decline. This study examines whether changes in adult survival could also have played a role. Adult Godwits were colour-ringed and resighted from 2002 through 2005 at four study sites in The Netherlands. Apparent adult survival was estimated in program MARK using Burnham’s model for both live resightings and dead recoveries. In addition, nest site fidelity was estimated at two of the sites by recording the distance between nest locations in successive years. Apparent adult survival was 0.93 +/- 0.03 in one study area and 0.81 +/- 0.04 in the other sites. Overall apparent adult survival was 0.83 +/- 0.03. These values are similar to estimates from the 1970s and 1980s. Nest site fidelity was higher in the site with highest survival (median distance between nests in successive years: 49 m vs. 252 m in the other site), suggesting that the difference in apparent survival may result from differences in emigration rates and are possibly underestimated. The results suggest that current adult survival is not different from rates 30 years ago, and therefore do not point to reduced adult survival as the driver behind the current population decline of Black-tailed Godwits.
Roodbergen, M., Klok, C. & van der Hout, A. 2008. Transfer of heavy metals in the food chain earthworm Black-tailed Godwit (Limosa limosa): Comparison of a polluted and a reference site in The Netherlands. Science of the total Environment 406: 407–412
The Black-tailed Godwit Limosa limosa is a migratory wader that favours wet meadows for breeding. The species has a Red List status in The Netherlands, as it strongly declined in numbers since the 1960s. Intensification of agriculture and land use change resulting in habitat loss are considered major causes of this decline. In some areas the breeding habitat is contaminated with heavy metals. Adult Godwits mainly feed on earthworms in the breeding season, which are known to accumulate heavy metals from the soil. This study investigates the transfer of heavy metals from the soil to the Black-tailed Godwit, which may have an additive negative effect on the viability of local populations. Heavy metal concentrations in soil, earthworms, and Godwit eggs and feathers at a polluted and a reference site were measured. The results suggest that some heavy metals are transferred from the soil to Godwits. Lead, Mercury and Cadmium were significantly higher in soils, earthworms, eggs and/or feathers which strongly suggests transport of these heavy metals from earthworms at the breeding site to Black-tailed Godwits. It remains uncertain to what level heavy metals in wintering and migratory sites added to the measured concentrations in feathers and eggs.
Klok, C., Roodbergen, M. & Hemerik, L. 2009. Diagnosing declining grassland wader populations
using simple matrix models. Animal Biology 59: 127–144.
Many populations of wader species have shown a strong decline in number in Western-Europe in recent years. The use of simple population models such as matrix models can contribute to conserve these populations by identifying the most profitable management measures. Parameterization of such models is often hampered by the availability of demographic data on survival and reproduction. In particular, data on survival in the pre-adult (immature) stage of wader species that remain in wintering areas outside Europe are notoriously difficult to obtain, and are therefore virtually absent in the literature. To diagnose population decline in the wader species; Black-tailed Godwit, Curlew, Lapwing, Oystercatcher, and Redshank, an existing modelling framework was extended in which incomplete demographic data can be analysed, developed for species with a pre-adult stage of one year. The framework is based on a Leslie matrix model with three parameters: yearly reproduction (number of fledglings per pair), yearly pre-adult (immature) and yearly adult (mature) survival. The yearly population growth rate of these populations and the relative sensitivity of this rate to changes in survival and reproduction parameters (the elasticity) were calculated numerically and, if possible, analytically. The results showed a decrease in dependence on reproduction and an increase in pre-adult survival of the population growth rate with an increase in the duration of the pre-adult stage. In general, adult survival had the highest elasticity, but elasticity of pre-adult survival increased with time to first reproduction, a result not reported earlier. Model outcome for the Black-tailed Godwit suggests that management has to focus on reproductive output and pre-adult survival, rather than on adult survival.
Roodbergen, M., van der Werf, B. & Hötker, H. 2012. Revealing the contributions of reproduction and survival to the Europe-wide decline in meadow birds: review and meta-analysis. J. Ornithol
In this review, available data on nest success, chick survival and reproductive output, and adult and juvenile survival of five meadow breeding waders in Europe is summarized. Meta-analyses on reproduction data show that chick survival declined strongly in the last 40 years in western Europe and that nest success declined in eastern Europe in the period 1995–2005, in Scandinavia in the period 1985–2005, and in western Europe in the period 1950–1980. Predation of nests has increased by ca. 40% in all five species in western Europe during the last four decades. Results on reproductive output, the number of fledglings produced per breeding pair, were less clear. An initial decline was apparent in Black-tailed Godwit Limosa limosa in the period 1985–1995, but there was a slight increase from 1995 onwards. The required reproductive output for a stable population is estimated between 0.6 and 1.6 fledglings per breeding pair. Estimates of juvenile survival varied between 0.36 and 0.4 and of adult survival between 0.7 and 0.95. Survival in Dutch Black-tailed Godwits increased from 0.7 in the 1960s to 0.8 in the last 30 years, due to an increase in survival during the non-breeding season. Possible explanations for this increase are a decrease in hunting pressure, a change in use of stopover and wintering areas, possibly related to an increase in rice production, a decrease in competition, and last but not least a trade-off with reproduction, so that a decrease in reproduction might cause an increase in adult survival rates. In all five species the results indicate that present population declines are caused by a decrease in reproduction, not in adult survival, and that reproductive output is presently too low to compensate for adult mortality.
Schekkerman, H. & Beintema, A.J. 2007. Abundance of invertebrates and foraging success of Black-tailed Godwit Limosa limosa chicks in relation to agricultural grassland management. Ardea, 95(1): 39-54.
Effects of agricultural intensification on availability of grassland invertebrates as food for chicks of the declining Black-tailed Godwit Limosa limosa were studied in The Netherlands. Invertebrates were sampled with photo-eclectors in wet grasslands used for intensive dairy farming (high fertiliser input, 2–3 cuts starting early to mid-May) and in a meadowbird reserve (moderate fertiliser input, one cut in mid-June). Invertebrates were slightly more abundant in reserve than in agricultural fields before the first cut of the latter. In the 4–6 weeks between the first cut of agricultural fields and that of reserve fields, invertebrates were much more abundant on reserve fields. This is the main period of Godwit chicks’ presence. Mean size of arthropods was similar under the two management regimes, but large Coleoptera were more abundant in agricultural fields early in the season. In both regimes arthropod biomass increased with sward height. In a foraging experiment, captive raised Godwit chicks ingested 31% fewer prey per unit time when foraging in cut agricultural grasslands than in uncut reserve fields, a difference large enough to compromise chick growth and survival. Wild broods strongly selected to stay in reserve fields, especially after agricultural fields had been cut, and travelled towards reserve fields over distances up to more than 0.5 km. Preference for reserve grasslands declined from early June onwards. This study has shown that modern intensive dairy farming negatively affects feeding conditions for Black-tailed Godwit chicks. The preference for tall vegetation puts Godwit chicks at risk of being killed directly during mowing. Increased mechanisation and the shift from hay to silage production have led to increasingly large areas of grassland being cut within a short period of time. Uncut refuges may become too small to accommodate all broods, and chicks in isolated pockets of tall vegetation may suffer increased predation risk. Postponing mowing dates, in reserves or on farmland, improves feeding and survival conditions for Godwit chicks feeding in the grassland sward, in addition to its beneficial effect on hatching success.
Schekkerman, H. & Boele, A. 2009. Foraging in precocial chicks of the black-tailed Godwit Limosa
limosa: vulnerability to weather and prey size. J. Avian Biol. 40: 369-379.
Self-feeding precocial development is associated with high energy requirements and potentially vulnerable to short-term reductions in food availability. Few studies have investigated development of foraging in precocial chicks and its sensitivity to environmental conditions. This study investigates time budgets and foraging behaviour in a meadow bird reserve (moderate fertiliser input, one cut in mid-June) during the 25-days prefledging period in the insectivorous chicks of the black-tailed Godwit Limosa limosa. Until 8-10 d old, parental brooding was the main determinant of chicks’ daily foraging time. Brooding decreased with age and temperature and increased during rainfall. Foraging time increased to 70-90% of the daylight period in chicks older than a week, during which distances of 3-12 km/day were covered. Chicks took 98% of their arthropod prey from the grassland vegetation. Prey ingestion rates increased in the first week and slowly declined thereafter, modified by wind speed, temperature and time of day. Chicks in poor body condition were brooded more than chicks growing normally and hence had less feeding time, potentially leading to a negative condition spiral under adverse conditions. However, no effect of condition on prey ingestion rate was found that would preclude recovery when conditions improve. Combining behavioural observations with data on energy expenditure revealed that mean prey size was small (1- 4.5 mg), necessitating a high feeding rate. Prey size increased notably after 7-10 days of age, coinciding with a decrease in walking speed, suggesting that chicks fed more selectively. Prey of older chicks approached the upper limit of sizes available in exploitable densities in the grassland vegetation, and this enhances the chicks’ sensitivity to variation in prey availability due to weather and agricultural practice.
Schekkerman, H. & Visser, G.H. 2001. Prefledging energy requirements in shorebirds: implications of self-feeding precocial development. The Auk, 118(4): 944-957.
Understanding ecological consequences of avian developmental modes requires knowledge of energy requirements of chicks of different positions in the precocial– altricial spectrum, but those have rarely been measured in birds with self-feeding precocial young. This study assessed prefledging energy budgets in chicks of Black-tailed Godwit (Limosa limosa) and Northern Lapwing (Vanellus vanellus) in the field and in the laboratory. Daily energy expenditure (DEE),measured by the doubly labelled water (DLW) technique, and daily metabolized energy (DEE plus energy deposited into tissue) increased proportionally to body mass at similar levels in both species. Total metabolized energy (TME) over the fledging period was 8,331 kJ in Godwits, 39% higher than predicted. That suggests that self-feeding precocial chicks have high energy requirements compared with parent-fed species, due to costs of activity and thermoregulation associated with foraging. Those components made up 50–53% of TME in the shorebirds, more than twice as much as in seven parent-fed species for which DLW-based energy budgets are available. In captive Godwits growing up under favourable thermal conditions with food readily accessible, thermoregulation and activity costs were 53–58% lower and TME was 26-31% lower than in free-living chicks. The proportion of TME allocated to tissue formation (13-15% deposited as tissue plus 10-12% synthesis costs) was low, and reductions in food intake may therefore lead sooner to reduced growth. Furthermore, the need to forage limits potential for saving energy by reducing activity in periods of food scarcity, because that will further decrease food intake. Self-feeding precocial chicks thus seem to operate within fairly narrow energetic margins. At the same time, self-feeding may allow birds to use food types that could not be profitably harvested if they had to be transported to the young.
Schekkerman, H. Teunissen,W. & Oosterveld, E. 2009. Mortality of Black-tailed Godwit Limosa limosa and Northern Lapwing Vanellus vanellus chicks in wet grasslands: influence of predation and agriculture. J Ornithol 150: 133–145.
Grassland-breeding shorebirds show widespread declines due to a reduction in breeding productivity following agricultural intensification. However, there is also concern that increasing predation causes further declines or precludes population recovery. This study assessed mortality by radio-tagging 365 chicks of Black-tailed Godwit Limosa limosa in 11 farmland sites in the Netherlands. Tagging and handling had no effect on the condition and survival of Godwit chicks. Fledging success was 0–24%. Mortality was highest in young chicks but remained considerable until after fledging. Losses were traced mostly to predators (70–85%; 15 species, predominantly birds), but at least 5–10% were due to mowing, and 10–20% were due to other causes, including entrapment in ditches and starvation. Predators most frequently identified were Grey Heron Ardea cinerea (11%), stoat/weasel Mustela erminea/nivalis (20%), Common Buzzard Buteo buteo (17%). Chicks staying in fields that were cut before the next radio check were found much more often as mowing victims and somewhat more often as prey remains than chicks in fields not cut, indicating that predation includes a limited amount of scavenging. The predation hazard for Godwit chicks was higher in recently cut or grazed fields than in the tall, uncut grasslands they preferred. Poor body condition increased mortality risk, not only from starvation but also from other causes. The results indicate that predation on Godwit chicks is increased up to threefold by intensive agricultural grassland use through a reduced availability of fields with protective cover, and possibly also by a reduction of food availability, leading to poor body condition or risky foraging behaviour. Changes in farming practice may therefore help reduce predation pressure, though only part of the high predation rate in Godwits was explained. Predator abundance probably has increased in Dutch wet grassland regions, and chick predation has become a factor that should be considered in planning the type and location of conservation measures.
Alves, J.A., Lourenço,P.M., Piersma, T., Sutherland, W.J. & Gill, J.A. 2010. Population overlap and habitat segregation in wintering Black‐tailed Godwits Limosa limosa. Bird Study 57(3): 381-391.
Distinct breeding populations of migratory species may overlap both spatially and temporally,
but differ in patterns of habitat use. This has important implications for population monitoring and
conservation. This study quantifies the extent to which two distinct breeding populations of the Black-tailed Godwit Limosa limosa , overlap spatially, temporally and in their use of different habitats during winter. Between 1990 and 2001 mid-winter counts were used to identify the most important sites in Iberia for Black-tailed Godwits. Monthly surveys of estuarine mudflats and rice-fields at one major site, the Tejo estuary in Portugal in 2005–2007, together with detailed tracking of colour-ringed individuals, are used to explore patterns of habitat use and segregation of the Icelandic subspecies L. l. islandica and the nominate continental subspecies L. l. limosa . In the period 1990–2001, over 66000 Black-tailed Godwits were counted on average in Iberia during mid-winter (January), of which 80% occurred at just four sites: Tejo and Sado lower basins in Portugal, and Coto Doñana and Ebro Delta in Spain. Icelandic Black-tailed Godwits are present throughout the winter and forage primarily in estuarine habitats. Continental Black-tailed Godwits are present from December to March and primarily use rice-fields. Iberia supports about 30% of the Icelandic population in winter and most of the continental population during spring passage. While the Icelandic population is currently increasing, the continental population is declining rapidly. Although the estuarine habitats used by Icelandic Godwits are largely protected as Natura 2000 sites, the habitat segregation means that conservation actions for the decreasing numbers of continental Godwits should focus on protection of rice-fields and re-establishment of freshwater wetlands. Effective monitoring of both Godwit populations requires counting periods to be scheduled in accordance with the relevant migration patterns, as counts in December or early January will largely comprise Icelandic Godwits whereas counts in late January and February will also record continental Godwits. The lack of any legal protection on more than 80% of the rice-field area in the lower basins of the Tejo and Sado rivers is of great concern given the huge proportion of the rapidly declining continental Godwit population that depends on this habitat.
Lourenço, P.M. & Piersma, T. 2008. Stopover ecology of Black-tailed Godwits Limosa limosa limosa in Portuguese rice fields: a guide on where to feed in winter: Capsule Conservation management of rice fields may be necessary to guarantee the availability of high quality stopover habitats. Bird Study 55(2): 194-202.
Conservation management of rice fields may be necessary to guarantee the availability of high quality stopover habitats. This study analyses habitat selection and quantifies the diet composition of birds in 120 rice paddies around the Tejo and Sado estuaries. Using water level and agricultural management of the fields as variables, habitat selection was analysed by compositional analysis. Godwit diet composition was quantified by faecal analysis, and food abundance was sampled to explain the observed habitat selection. Evidence was found of higher use of flooded and ploughed paddies than expected from their relative abundance. These fields have the highest densities of buried rice kernels, which seem to be the main food source for Black-tailed Godwits. Rice kernels were found in 78% of faecal samples (N=58) and composed 94% of the diet. Currently, Godwits find good foraging areas in Portuguese rice fields, feeding primarily on rice kernels that are mostly found in flooded ploughed fields. Changes in rice farming can lower habitat quality through more efficient harvesting methods that reduce the amount of spilled rice seeds and better drainage systems that allow farmers to keep their fields dry during winter so stubble can be burned. Another thread is late ploughing, as the birds stay in the area for a limited period of time. Because of the man-made nature of their requirements it should be possible to install relevant land-use practices that guarantee the availability of high quality stopover sites. Fields should be kept flooded throughout autumn and winter, at least part of the ploughing ought to take place between December and February and the substitution of rice by other crops should be avoided.
Lourenço, P.M., Kentie, R., Schroeder, J., Alves, J.A., Groen, N.M., Hooijmeijer J.C.E.W & Piersma, T. 2010. Phenology, stopover dynamics and population size of migrating Black-Tailed Godwits Limosa Limosa Limosa in Portuguese rice plantations. Ardea, 98(1): 35-42.
Between 2005/06 and 2008/09 Black-tailed Godwits Limosa l. limosa were studied staging in the rice fields surrounding the Tejo and Sado estuaries, Portugal. Godwits were counted weekly and flocks were scanned for colourringed individuals. An analysis was made of phenology, dynamics of the stopover, and estimated size of the Portuguese staging population as well as the total western limosa population. Godwits started arriving in January. Numbers peaked in the second half of February, after which they quickly departed from the area. Comparison with previous records suggested that numbers have decreased since the early 1990s, and that Godwits currently peak later than some 15 years ago. Individual staging durations averaged 22.6 days in 2007 and 25.3 days in 2009, and increased towards the end of the staging period. A total of 59200 birds used the area in 2007 and 53100 in 2009. Using estimates for the proportion of colour-ringed birds in the flocks, the population size of the western part of the L. l. limosa population is estimated at 133151–140722 birds. This is higher than previous estimates based on inventories of the breeding population, but accounts for the non-breeding segment of the population. Approximately 38–44% of the NW European Black-tailed Godwit population stage in Portugal. It is argued that processes in Iberia are not likely to have contributed to the population decline as the area for rice cultivation has increased. Nevertheless, as Godwits staging in Iberia are totally dependent on human-made habitats, changes in rice farming practices could have great impact on the total population size.
Lourenço, P.M., Mandema, F.S., Hooijmeijer J.C.E.W, Granadeiro, J.P. & Piersma, T. 2010. Site selection and resource depletion in black-tailed Godwits Limosa l. limosa eating rice during northward migration. Journal of Animal Ecology 79: 522–528.
During migratory stopovers, animals are under strong time stress and need to maximize intake rates. This study examines how Black-tailed Godwits Limosa l. limosa react to resource depletion by studying the foraging ecology and foraging site selection of birds staging in rice fields surrounding the Tejo and Sado estuaries (Portugal) during their northward migration stopover (January–March 2007). An analysis was made on Godwit abundance and foraging behaviour, availability of rice was sampled in the fields and a functional response model was used to predict the giving-up density (GUD) of rice kernels when Godwits should give up a rice field. Sightings of individually colour-marked birds were used to verify whether individuals moving between rice fields confirmed the predicted GUD. Godwit intake rates at different rice densities fitted Holling’s functional response curve. The predicted GUD of rice necessary to balance allometric estimates of daily energy expenditure (DEE) and measured time budgets were confirmed by GUD measured in the field. The minimum intake rate to sustain the calculated DEE of 567 kJ/day was determined to be 4.73 rice kernels/min, which gives a GUD of 123 rice kernels/m2. Individually marked birds moved towards rice fields with higher rather than lower rice densities more often than randomly expected. Of the movements of 31 colour-ringed birds 77% were towards fields with higher rice abundance, while only 10% moved into fields estimated to have less rice. These birds increased the measured intake rates after this move. Godwit foraging caused a decrease in the rice density of individual fields during the stopover period. Despite this, overall intake rates remained constant as Godwits reacted to resource depletion by moving to a new foraging site as soon as their intake rate falls below the required levels to achieve DEE. As rice kernels in winter are a non-renewable resource, fields that become depleted will no longer represent available habitat for the remaining staging period, thus depletion reduces the availability of good quality foraging sites during the stopover period. This effect can be partially compensated by phased ploughing of the rice fields, which offers new feeding opportunities, but requires frequent switches between sites.
Brink, V. van den, Schroeder, J., Both, C., Lourenço, P.M., Hooijmeijer, J.C.E.W & Piersma, T. 2008. Space use by Black-tailed Godwits Limosa limosa limosa during settlement at a previous or a new nest location: Capsule Black-tailed Godwits first return to the nest location of the previous year, even when moving to a different nest location later that season. Bird Study 55(2): 188-193.
Black-tailed Godwits first return to the nest location of the previous year, even when moving to a different nest location later that season. This study examines the use of space by Black-tailed Godwits during the two months before egg-laying to two weeks afterwards. The study was conducted in two sites: an extensively managed meadow and a grassy marshland area in the Netherlands. The spatial distribution of sightings of eventually site-faithful birds with birds that changed nest location was examined, and related to the change of the distance to their previous year’s and current nest-site in the period until egg-laying. Using a log-likelihood model the differences in distance to the respective nests change over the course of the season was assessed. In total 21 birds and 163 observations were used in the analysis. All birds were observed first near their previous year’s nest-site, and remained there for most of the pre-laying period. Birds that subsequently changed nest location (N=9) made the move only about five days before egg-laying and were more wide-ranging earlier on. The return to the previous nest-site suggests that a decision to move is made only after considerable time investment near the previous nest-site. This indicates that site-faithfulness in Black-tailed Godwits is conditional on experiences after return to the nesting area.
Schroeder, J., Piersma, T., Groen, N.M., Hooijmeijer, J. C. E. W., Kentie, R., Lourenço, P.M., Schekkerman, H. & Both, C. 2012. Reproductive timing and investment in relation to spring warming and advancing agricultural schedules. Journal of Ornithology 53:327–336.
Advances in mowing schedules have led to early and rapid declines in the seasonal food availability for, and survival rates of, chicks of grassland-breeding waders. Concurrently, increased levels of soil fertilization may have improved food abundance for adults. These developments are assumed to have resulted in an advancement of laying during 1930-1976 in several meadowbird species, including Black-tailed Godwits. Despite an apparent selective advantage of early breeding, after 1976 Godwits stopped advancing their laying dates. This study analyses the timing of breeding and reproductive investment in Dutch Black-tailed Godwits relative to recent changes in agricultural practices and climate during 1976-2007. Early and late spring temperatures and precipitation in March were used as indicators for the timing of fertilizer application and mowing, and also as qualitative measures of relative food availability for adults and chicks. When precipitation was higher in March, Black-tailed Godwits laid earlier. Following warmer winters, the earliest females laid larger eggs, which hatched heavier chicks with a higher survival probability. Godwits take on average 27 days from the start of egg-laying to hatching, and chicks need to forage in the grass canopy for at least 24 days before fledging. Thus, Godwits should start egg laying at least 51 days before mowing, which at present means that in intensively managed grasslands they should lay before 20 March. The observed laying date however is mid-April. It remains uncertain whether adjustment of laying date is constrained by an inflexible annual cycle or by the food sources for adults during laying. It is suggested by the authors that the positive effect of an increasing March precipitation on invertebrate abundance may be constrained by the current Dutch policy of rigid control of the water table. This policy prevents Godwits from further advancing laying dates, which would increase their chick’s survival prospects under increasingly early mowing schedules. Policy-makers should, next to delaying mowing schedules, also consider reduced draining in early spring as a tool to help stop the population decline of the Black-tailed Godwit.
Kleijn, D., Dimmers, W.J., van Kats, R.J.M & Melman, T.C.P. 2009. Het belang van hoog waterpeil en bemesting voor de Grutto: I. de vestigingsfase. De Levende Natuur 110: 180-183. [In Dutch with English summary]
Despite decades of experience with conservation management at meadow birds, there is a lot of discussion in The Netherlands about which groundwater levels and fertilization regimes are most effective. Both factors are important determinants for earthworm availability and accessibility for parent birds. The basic assumption underlying conservation management is that food availability affects settlement densities. This study explores this assumption by reviewing a number of recent studies that examined how water level and food availability is related to settlement densities of Black-tailed Godwits. In five out of six studies the settlement density of Godwits was positively related to groundwater level. Settlement density was only positively related to the density of earthworms when groundwater levels were high. High groundwater levels seem to be a key factor to the sustained conservation of Black-tailed Godwit populations because it may be used to lure breeding pairs to areas in which good chick foraging habitat can be created. Another key factor influencing settlement is the avoidance of potential predator perches (high structures like trees, buildings, hedgerows). The density of Godwit breeding pairs increases with distance to these perches (maximum from 300m).
Kleijn, D., Dimmers, W.J., van Kats, R.J.M & Melman, T.C.P. 2009. Het belang van hoog waterpeil en bemesting voor de Grutto: II. de kuikenfase. De Levende Natuur 110: 184-187. [In Dutch with English summary]
In the Netherlands conservation management aimed at Black-tailed Godwits is mainly targeted to enhance settlement densities. Grasslands in breeding areas are fertilized and water levels are manipulated to enhance the availability and accessibility of earthworms, the main prey items of adult Godwits. The decline of the Dutch Godwit population is, however, driven by poor chick survival. This study explored in what way groundwater level and fertilizer application influenced the quality of the foraging habitat of Godwit chicks. The main prey items of chicks, vegetation inhabiting arthropods, were influenced contrastingly by groundwater and fertilization, resulting in little variation in arthropod abundance across different groundwater levels or fertilization application rates. Vegetation height increased with lower groundwater levels and higher fertilization rates, making the sward less accessible to foraging Godwit chicks. The quality of the chick habitat therefore seems to be primarily determined by vegetation height. Vegetation growth, in turn, was primarily related to groundwater levels, whereas the effects of fertilization were only apparent when groundwater levels were low. The maintenance of high groundwater levels seems to be key to the creation of high quality foraging habitat for Black-tailed Godwit chicks.
Johansson 2001. Habitat selection, nest predation and conservation biology in a Black-tailed Godwit (Limosa limosa) population. PhD Thesis University of Uppsala.
This thesis focuses on a Black-tailed Godwit (Limosa limosa) population, consisting of 35-40 pairs, that breeds on a grazed shore meadow on SE Gotland, Sweden. The small population size makes it more prone to extinction due to chance events, than a larger population. The Godwits showed microhabitat preferences when choosing nest sites. Godwit nests had higher vegetation over the nest cup, lower surrounding (1-3 m) vegetation and different plant species composition, as compared to random sites. Breeding near conspecifics or other wader species, especially lapwings (Vanellus vanellus) and further away from potential predator perches were the most important factors in decreasing nest predation. A comparison between different shore meadows along the east coast of the island revealed that large, open areas suffered less from nest predation. Thus, shore meadows suitable for breeding Godwits should be large and without trees or other predator perches and have a grazing regime that favours variation in vegetation height. Over 80% of previously ringed adults returned each year, but very few birds ringed as chicks were recovered (2-3%). Hatching success was 55-60% for all observed nests. To predict the future of the current population, demographic data were used in an ecological risk analysis. The simulations showed that the Gotlandic population will not survive the coming 40 years without immigration. Black-tailed Godwits are divided into three subspecies. Genetic analyses (mtDNA) revealed that all subspecies had unique haplotypes and there was a clear geographic structure among subspecies. Within the limosa subspecies, Godwits on Gotland and Öland showed a high proportion of rare haplotypes, but no genetic variation was found in Dutch birds. These results imply that black-tailed Godwits on Gotland and Öland have high conservation value.
Baldi, A., Batary, P. & Erdos, S. 2005. Effects of grazing intensity on bird assemblages and populations of Hungarian grasslands. Agriculture Ecosystems & Environment 108: 251-263.
Agricultural intensification is responsible for the dramatic decline of farmland bird populations in the European Union (EU). The joining of eight Central and Eastern European (CEE) countries to the EU will re-structure agriculture there. One of the main threats is the intensification of farmland management. Can agri-environmental programs balance the expected decline in bird assemblages of the CEE countries if farming will be intensified? This study compares bird assemblages of 42 extensively and intensively grazed paired fields in three regions of Hungary (alkali steppes and meadows in Central Hungary and alkali steppes in Eastern Hungary). Bird assemblages varied significantly across regions and grazing intensity. Intensively grazed sites showed a higher species number and diversity, but lower densities than the extensive sites. This is probably the consequence of higher landscape diversity of intensive sites, which included farm buildings, shelters, wells and other structures. Several bird species, mainly with European conservation concern, showed contrasting responses to grazing intensity in the three regions, including the Black-tailed Godwit Limosa limosa,. Therefore, threat and sensitivity to grassland characteristics are correlating. Although many of the declining species of Western Europe are still abundant in Hungarian grasslands, the results project the threat of the expected intensification. This study showed that it is not possible to provide a general grassland management scheme that will favour all bird species in all regions of Hungary. In the process of integrating to the EU and re-structuring agriculture, the establishment of scientifically sound schemes is urgent.
Shubin, A.O. & Ivanov, A.P. 2005. Ecological segregation of migrating waders on steppe water bodies in European Russia. Zoologichesky Zhurnal 84: 707-718.
Spatial distribution and feeding behaviour of 12 wader species inhabiting water bodies in southeastern European Russia (mostly within the Republic of Kalmykia) were analysed. The main contribution into waders' segregation is related to the interspecific differences in their geographic distribution, whereas that of the differences in feeding behaviour of waders is insignificant. The majority of the waders studied have an independent distribution as a result of heterogeneous environment and specific biological requirements. The distribution of Black-tailed Godwit (Limosa limosa L.) is determined by the abundance of Chironomidae larvae. The distinct interspecific ecological segregation without interference in the conditions of high food supply indicates the low probability of trophic competition among waders dwelling in steppe water bodies of European Russia.
Gill, J.A., Langston, R.H.W., Alves, J.A., Atkinson, P.W., Bocher, P., Cidraes Vieira, N., Crockford, N.J., Gélinaud, G., Groen, N., Gunnarsson, T.G., Hayhow, B., Hooijmeijer, J., Kentie, R., Kleijn, D., Lourenço, P.M., Masero, J.A., Meunier, F., Potts, P.M., Roodbergen, M., Schekkerman, H., Schröder, J., Wymenga, E. & Piersma, T. 2007. Contrasting trends in two Black-tailed Godwit populations: a review of causes and recommendations. Wader Study Group Bull. 114: 43–50.
In recent decades, the West European population of Black-tailed Godwits, Limosa limosa limosa, has declined in size at a quite alarming rate, while the Icelandic population, L. l. islandica, has undergone a rapid increase in population size. In 2007, a workshop was held with the aims of identifying the likely causes of the population changes and providing recommendations for the conservation of both populations. The available evidence strongly suggests that changes in productivity as a consequence of agricultural intensification are the most likely driver of the decline in L. l. limosa, although the concentration of much of the population in just a few sites in winter and spring is likely to exacerbate their vulnerability to future habitat changes. Agricultural and climatic changes are implicated in the expansion of L. l. islandica, and the availability of both intertidal mudflats and wet grasslands as foraging habitats appears to be very important across much of the winter range of this population. Recommendations for actions to conserve L. l. limosa are provided. Improve prescriptions and targeting of agri-environment schemes (AES) in the breeding range, focusing efforts in areas with high groundwater levels and open landscapes to attract Godwits and avoid high predator densities, in order to have the potential to improve overall productivity. Include raising groundwater levels in the Netherlands AES prescriptions (as is the case in the UK, Denmark and Germany). Incorporate the creation of small-scale habitat mosaics into management prescriptions, to provide both foraging and predator avoidance options throughout the season. Improve conservation of key wetland habitats in Iberia and Africa, either through maintenance of support for rice production or restoration of wetlands, as well as designation of more sites under relevant national legislation and international treaties (EU Birds and Habitats Directives, Ramsar Convention etc.). In view of the severe continuing declines of this population, take a precautionary approach and ban hunting of Godwits, at least temporarily, where there is any risk that birds from this population could be involved (especially late migrating juveniles in autumn), until productivity is increased to a level that can sustain a certain amount of additional mortality of adults and immatures.
Belting, H., Körner, F., Marxmeier, U. & Möller, C. 1997. Wet meadow management in the Lake Dümmer area- Population changes and breeding success of meadow birds. Vogelkundliche Berichte aus Niedersachsen, 29: 37-50. [in German with English summary].
In 1987 a program of nature reserve management was initiated in the Dümmer area in Niedersachsen, Germany. It covers an aera of 42 km2 of peatland and wet pastures. Agriculture use changed to more extensive use. In part of the area, nature reserve the Ochsenmoor (1029 ha), water levels were raised resulting in a mosaic vegetation pattern with growth only starting in June. Hedgerows and trees were removed in order to decrease predation pressure. Following the lowering of groundwater levels in grasslands in Niedersachsen, Germany numbers of Black-tailed Godwits decreased. The fledging success approximated null until the early 1990’s. In the whole area numbers of Godwits are still decreasing but in the rewetted Ochsenmoor numbers are now stable in part of the area. Only in parts of the area where water levels were raised breeding success of Godwits increased during the past 2 years.
Struwe-Juhl, B. 1995. Effects of conservation measures in the Hohner See area on numbers, breeding success and feeding ecology of the Black-tailed Godwit( Limosa limosa). Corax, 16: 153-172. [in German with English summary].
In 1993 the effects of conservation measures on breeding success and feeding ecology of Black-tailed Godwits were examined in the Hohner See area (Schleswig-Holstein, Germany). The water level was raised and until 1 July all agricultural activity was stopped. The raised water level reduced the compactness of the soil on temporarily flooded meadows. In May penetration resistance on intensively used meadows was 95-130 N/m2 and on extensively used soils 55-70 N/m2. Penetration resistance on intensively used meadows temporarily exceeded the theoretical limit of 125 N/m2 above which Godwits are unable to feed on earthworms successfully. Vegetation height differed between both meadow types ( extensive 15.9 +/-5cm vs intensive 30.4 +/-5.5cm). The high dense vegetation and dry ground on intensively used meadows caused several pairs to leave their nests permanently. In March and April Godwits fed on earthworms, which were available in high densities because of the raised groundwater level. The preferred feeding areas were meadows which were not permanently flooded at a height of 20 cm above water level of the lake. In these areas earthworm densities were highest. Highest earthworm densities were measured in March. Densities of earthworms decreased during the breeding season. On extensively used meadows earthworm density decreased from 208/m2 in March to 96/m2 in June. On wet Carex meadows the densities were much lower. Godwits breeding on such meadows regularly fed outside these meadows. Since the water level was raised in the area in January 1991 breeding numbers increased. Hatching success depends on agricultural use. On intensively used meadows hatching success was 38% (N=8 clutches), on extensively used meadows success was 77% (N=22 clutches). Total hatching success for the Hohner See area was 71% (N=28 pairs). Breeding success was 0.75 juv/pair which is much higher than those recorded on conventionally utilized meadows in the lowlands of the rivers Eider, Treen and Sorge. The results show that Godwits can react quickly to habitat improvement by reducing agricultural utilization, raising water level and temporarily flooding of meadows in early spring.
Schekkerman, H. & Müskens, G. 2000. Do black-tailed godwits Limosa limosa produce sufficient young to sustain populations in agricultural grasslands? Limosa 73: 121–134 [in Dutch with English summary].
Numbers of Black-tailed Godwits have decreased in the Netherlands with 33% between 1990 and 2000 to 58000 pairs. From 1997 to 2000 habitat preferences and habitat use was studied using radio-telemetry in 10 grassland breeding areas in the Netherlands. Grasslands were intensively managed but differed in grazing intensity and mowing regime. In total 89 Godwits (1/pair) were radio-tagged. Ten pairs abandoned their nests shortly after capture, 19 pairs lost their clutches due to mowing or predation. Data presented is based on 62 broods. Based on birds that lost their clutch after being tagged, renesting rate after clutch loss was estimated at 100% in one site and 50% in the others. Renesting rate declined in the course of spring, with no replacement clutches produced after late May. For the ten sites/years the average proportion of nests with 1 egg hatched was 54%, with a mean of 3.3 chicks per successful nest. On average 26% of these survived to fledging (24 days). Numbers of chicks fledged/breeding pair were 0.56 (range 0.16-0.91). Data on Nature reserves are scarce but indicate chick survival rates of 35% and breeding success of 1.1 young/pair. The required reproductive output for a stable population is estimated between 0.5 and 0.7 young/ breeding pair per year. In half to two-third of the grasslands investigated preproduction success appears to be insufficient to compensate for adult mortality. Data suggests that chick survival and breeding success increase with the proportion of grassland mown late (beyond 31 May). It is concluded that agricultural nature management schemes can only safeguard a self-sustaining Black-tailed Godwit population on farmland when practical measures are applied at a larger scale, or more effectively, than at present.
Bos, D., Grigoras, I. & Ndiaye, A. 2006. Land cover and avian biodiversity in rice fields and mangroves of West Africa. A&W-report 824. Altenburg & Wymenga, ecological research, Veenwouden. Wetlands International, Dakar.
The rice and mangrove region, stretching among the West African coast from the south of Senegal through Gambia, Guinea-Bissau and Guinea as far as Sierra Leone, incorporates important habitat for Black-tailed Godwits. This study quantified the importance of different habitat types using remote sensing and systematic bird density counts. Most observations were made in rice fields (N=26). Average density in the rice fields was 0.77 +/- 0.4 Godwits/ha (N=2657), densities in other habitats were negligible. The extrapolated value for numbers of Black-tailed Godwits in the area adds up to 87000 +/- 97000. Including other habitat (natural vegetation and bare upper tidal flats)the entire region harbours 101000 +/- 100000 individuals. This is a realistic estimate compared to the estimated European population of >99000 pairs and the Eastern-Atlantic flyway population of 183000 individuals. However, because the confidence intervals are so high, the estimate is not very robust. Black-tailed Godwits were found in humid fields with vegetation height above 25 cm and with less than 25% cover.
Kentie, R., Hooijmeijer, J.C.E.W., Both, C. & Piersma, T. 2011. Black-tailed Godwits in space and time 2007-2010. University of Groningen. [In Dutch]
This study presents results of a 4 year study on factors affecting population dynamics of Black-tailed Godwits in Dutch intensively (low groundwater level, early mowing date, mono-culture of protein rich grasses) used and extensively (high groundwater level, postponed mowing date, mosaic of herbs and grasses) used meadows in Friesland. The total area studied was 8471ha of which 20% was extensively used. Density of breeding pairs was 6 times higher on extensive meadows. Hatching percentage was 32% (range 23-44%, N=491 clutches) on intensive and 54% (range 44-67%, N=830 clutches) on extensive meadows. Return rates of ringed chicks raised on intensive meadows in the next year was 10 times lower compared to chicks raised on extensive meadows (0.4% vs 4.3%). The combined chance for a chick to return as an adult bird was approximately 17 times lower when raised on intensive meadows. Adult survival did not differ between intensive and extensive meadows. Using demographic parameters of the study modelling showed that intensive meadows mostly function as sink populations (reproduction< mortality) while extensive meadows in some years function as a source population. To stop population decline the crucial factors are nesting success and chick survival. High reproduction success can only be attained in extensively used meadows with high groundwater levels and a postponed mowing date (after 15 June), which are characterized by a mosaic vegetation consisting of herbs and grasses yielding sufficient large prey for chicks. Conservation management therefore should not focus on intensively used meadows which functions as an ecological trap. Since Black-tailed Godwits show site-faithfulness on return to the nesting area it is important to create sufficiently large extensively used meadows (size >130 ha). Management should focus on turning sink areas, which are adjacent to extensively used areas, into extensively used meadows to create robust Godwit habitat.
Márquez-Ferrando, R., Hooijmeijer, J., Groen, N., Piersma, T. & Figuerola, J. 2011. Could Doñana, SW Spain, be an important wintering area for continental Black-tailed Godwits Limosa limosa limosa? Wader Study Group Bull. 118(2): 82–86.
The Doñana National and Natural Park (SW Spain) is an important stopover site for the declining nominate subspecies of the Black-tailed Godwit Limosa limosa limosa . The presence of three satellite-tagged limosa in southern Iberia throughout the entire winter of 2009–2010 proved Iberia (Spain and Portugal), formerly classified as a stopover area, to be an overwintering area for some individuals. Aerial surveys and ground counts are performed every month in Doñana. These censuses show that in recent years on average 10000–20000 Godwits are still present in October and November but it is unclear whether these birds represent the islandica or limosa subspecies, or a combination of the two. Among about 15000 godwits, 109 different colour-ringed birds were observed of which 91 (83%) were of the nominate race, four (4%) were from the Icelandic race L. l. islandica and 14 (13%) were indeterminate. This suggests that part of the continental Black-tailed Godwit population remains in Europe instead of migrating to their traditional W African non-breeding quarters. Proportionately more adults occur there than first or second year birds. The data also suggest that more adult males may occur there than adult females, but this needs to be confirmed with more resightings in future expeditions. If confirmed, it might be evidence of a tendency for males to winter closer to the breeding grounds than females, as has been found in other species such as Western Sandpiper Calidris mauri.
Thorup, O. 2004. Status of populations and management of dunlin Calidris alpine, ruff Philomachus pugnax and Black-tailed Godwit Limosa limosa in Denmark. Dansk Orn. Foren. Tidsskr. 98: 7-20.
The total Danish population of Black-tailed Godwits was 709 pairs in 2000-02; 4% more than in 1964-72, but only 76% of the 935 pairs present when the population peaked in 1977-82. Danish breeders constitute a small but growing proportion of the world population of L. l. limosa (0.5% in the mid-1980s, 0.7% in 2002). During the last 20 years the major European populations in the Netherlands, Germany, Poland and Belarus halved, and the subspecies is now of particular conservation concern.
An analysis of management practises in the 25 most important meadow bird breeding sites in Denmark identified four key elements in good management: 1) the maintenance of a high freshwater table in the meadows, 2) absence of fertilizer application, 3) grazing with cattle in moderate densities and a fairly late release date (late May-early June), 4) regular mowing late in the season (July-August). Most likely, the introduction of strict regulations concerning these four management tools in management plans for EC Special Protection Areas designated to protect breeding meadow birds would be necessary in order to safeguard viable populations of Dunlin, Ruff and Black-tailed Godwit in Denmark, where elements (1) and (4) in particular are rarely practiced nowadays.
Delany, S., Scott, D., Dodman, T. & Stroud, D. (eds) 2009. An atlas of wader populations in Africa and Western Eurasia. Wetlands International, Wageningen, The Netherlands.
Limosa limosa breeds in Europe from NW France and Belgium north to Southern Sweden and Finland eastwards to the southern Ural Kyrgyz steppes and east in western Siberia (at about 900E). Three subspecies are generally recognized. L.l. islandica (population estimate 47000) breeds mainly in Iceland and winters in Britain, Ireland and western France to Morocco. L.l.melanuroides has a disjunct breeding distribution in central and eastern Siberia, eastern Mongolia, north-eastern China and spends the non-breeding season in south east Asia, New Guinea and Australia. L. l. limosa breeding in Europe have several migration routes. The western breeding population of L. l. limosa (population estimate 160000-180000) stage in Spain, Portugal, Morocco and winters mainly in west Africa (Senegal, Guinea-Bissau). First year birds make several short autumn flights along the Atlantic coast and into West-Africa. Those not returning to breed spend the following summer in West-Africa or move east into Mali. Much less is known about the migrations of the east European breeding population in Ukraine, Belarus and Russia (population estimate 90000-165000). These birds moult in the Black Sea region, then cross the Mediterranean and Sahara to winter in tropical Africa from Mali and Lake Chad eastward. Godwits breeding east of the Urals in west and central Asia (population estimate 25000-100000) migrate either to the south-west (Middle East and eastern Africa as far as Zimbabwe, Botswana, Namibia) or south-east (Pakistan, India). It is unclear to what extent these populations mix on the breeding grounds.
Kube,J .,Korzyukov, A.I., Nankinov, D .N., Münster, O.A.G. & Weber, P. 1998. The northern and western Black Sea region- the Wadden Sea of the Mediterranean flyway for wader populations. International Wader Studies 10: 379-393.
This review summarises some available information up to 1993, about wader populations using the Mediterranean flyway with special reference to the northern and western Black Sea region. It is unknown how many Black-tailed Godwits breeding in Hungary and Ukraine use the Mediterranean flyway. Estimates for the number of breeding pairs and winter totals are unavailable. A varying number of 5000-10000 birds winter in the Mediterranean area. Numbers depend on weather conditions, the availability of prey in the lagoons of the Black Sea varies with wind direction causing irregular water levels. The majority of east European Godwits winter in West African inland sites in the Niger inundation zone and around Lake Chad. It is possible that east European Godwits are also to be found among the 15000-30000 birds wintering in Sudan. The maximum simultaneous count of Godwits on spring passage in south-east Europe is about 50000 birds. This figure does not include about 5000 birds staging in Italian wetlands on spring migration. The northern and western Black Sea region is an important moulting site for Godwits in July and August. In contrast to the spring passage, birds in autumn also rest in small flocks on inner mudflats of the Danube delta.
Longoni, V. 2010. Rice Fields and Waterbirds in the Mediterranean Region and the Middle East. Waterbirds, 33(1): 83-96.
In southern Europe, rice (Oryza sativa) is one of the most important agricultural crops. Relationships between rice fields and bird occurrence are well studied for some taxa while quantitative data are lacking for other, more secretive, species. Iberian rice fields are among the most important stopover sites for Black-tailed Godwit. Because not all crops provide the same value for wildlife, conversion of rice fields to the cultivation of other cereals would likely be harmful to waterbirds. Although the main factors that are detrimental (high levels of chemical use, repeated dry phases during summer, conversion to dry cultivation, stubble burning) or favourable (maintenance of water throughout the growing cycle, winter flooding, vegetation along field margins) to waterbirds are known, more research on the details of field management would be valuable. Ploughing and flooding harvested fields increases availability of kernels to waterbirds. The introduction of stripperheader harvesters could represent a deleterious harvesting technique due to the reduced amount of rice that remains on the soil. Information on waterbird use of rice fields in the Middle East is completely lacking in the international scientific literature, and the subject is neglected in regional journals. Nonetheless, these areas are undoubtedly of great interest for bird conservation. Iran and Iraq both have extensive natural wetlands, and the region straddles the Eastern and Western Palaearctic and lies on an important migratory route for Eurasian breeding birds.
Davydenko, I. & Serebryakov, V. 2008. Present status and numbers of Curlew (Numenius arquata L.) and Black-tailed Godwit (Limosa limosa L.) in Ukraine. Acta Zoologica Lituanica, 18(3): 211-216.
The 2001-2002 research into the distribution and numbers of the Curlew and Black-tailed Godwit was conducted within the framework of the programme aimed at the evaluation of the status and numbers of breeding populations of OMPO-priority bird species in the Ukraine. The spring arrival of the Black-tailed Godwit can be observed at the end of March in the Crimea and on the north-western coast of the Black Sea, and at the beginning of April in the forest (Polissya) and forest steppe zones. The breeding season starts at the end of April – beginning of May. In the forest-steppe zone the Black-tailed Godwit breeds more often near fishponds (average density 2.02 pairs/km²), while in the forest zone it favours boggy meadows (average density 3.3 pairs/km²). About 4000-5500 pairs of the Black-tailed Godwit breed in the territory of the Ukraine. For comparison, 7000-8000 breeding pairs are recorded in Poland and 6000-8500 pairs in Belarus. In boreal ranges, autumn migration starts at the end of July already, but mass migration occurs at the end of August, and lasts till the end of September, though cases of bird migration in October and November are also recorded, especially in southern ranges. During autumn migration of large flocks of birds numbering up to 8000 individuals are observed in the Sivash area. At the end of the 20th century 3000-5000 birds were killed by hunters during one season in the Azov-Black Sea region. A small number of birds sometimes remain solitarily or in small groups to winter mainly in the region of the Azov-Black Sea seaside. Rare cases of wintering Black-tailed Godwits are reported from the Crimea and the Danube delta. A few ring recoveries of shot Godwits showed that birds breeding in the Baltic States migrate south over the territory of the Ukraine.
Schmitz, M., Sudfeldt, C., Legge, H., Mantel, K., Weber, P. & Marinov, M. 1999. Spring migration of waders in the Razim-Sinoie lagoon system south of the Danube Delta, Romania. Wader Study Group Bull. 90: 59-64.
Spring migration patterns and waterfowl numbers were surveyed from 1990-96 in the Razim-Sinoie lagoon system south of the Danube delta, Romania (550000 ha). The Razim-Sinoie lagoon system is situated in the south of the delta. Lakes Razim, Golovita, Zmeica and Sinoie are large and brackish with vast shallow sections and reed beds. The water level depends on climatic conditions and freshwater input from the Danube, and is quite variable. Especially strong winds can create large open mudflats which are suitable habitats for waders. Mean spring counts for Black-tailed Godwits peaked at 9075 (N=4 counts) in March, decreasing in April from 5567 (N=6 counts) to 373 (N=3 counts) to 20-40 in May.
Schielzeth, H., Kamp, J., Eichhorn, G., Heinicke, T. Koshkin,M.A., Lachmann, L., Sheldon, R.D. & Koshkin, A.V. 2010. Wader, gull and tern population estimates for a key breeding and stopover site in Central Kazakhstan. Bird Conservation International 20: 186-199.
Siberian waders are mainly long-distance migrants, many of which follow the coastal flyways of Western Europe and Northern Africa, or migrate along the East Asian coasts. Others migrate inland across Western Asia, and these can be assigned to three flyways: (a) the Black-Sea/Mediterranean flyway via Western Asia, Eastern Europe and the Caucasus region to the Mediterranean Basin and West Africa, (b) the West-Asian-East-African flyway via Central Asia to the Middle East, Southern Asia and Eastern Africa and (c) the Central Asian flyway via Central Asia to the Indian Subcontinent. This study provides recent population size estimates and phenology data for waders for the Tengiz-Korgalzhyn region, Kazakhstan. Surveys were conducted between 1999 and 2008 and present estimates of population size as well as information on phenology and age structure for 50
species of Charadriiformes. Numbers of Black-tailed Godwit were in spring (March-mid June) 320-350 and during summer (end June-November) 8100-11500. Godwits show large post breeding moulting aggregations in the study region. The region contains 93 sites that qualify for Important Bird Areas (IBA). About half of them are protected in a state nature reserve, while an additional 20% are recognised as IBAs. Nevertheless, 28 important sites are currently not recognised as IBAs nor are they protected by other conservation means. These sites require conservation attention.
Rahmani, A.R. & Shobrak, M.Y. 1992. Glossy Ibises (Plegades falcinellus) and Black-tailed Godwits (Limosa limosa) feeding on Sorghum in flooded fields in Southwestern Saudi Arabia. Colonial Waterbirds 15: 239-240.
Nearly 400 Glossy Ibises (Plegadis falcinellus ) and a similar number of Black-tailed Godwits (Limosa limosa ) were seen foraging on standing crops of sugar sorghum (Sorghum bicolor ) in inundated fields near Hakimah Dam in south-western Saudi Arabia. Godwits were seen hovering/frying and plucking ripe grains from sorghum follicles, while ibises sitting momentarily on half bent plant stems also plucked grains from panicles. This foraging behaviour resulted in substantial crop damage.
Höglund, J., Johansson, T., Beintema, A. & Schekkerman, H. 2009. Phylogeography of the Black-tailed Godwit Limosa limosa: substructuring revealed by mtDNA control region sequences. J Ornithol 150: 45–53
This study assessed variation in partial mtDNA control region sequences among Black-tailed and Hudsonian Godwits (L. haemastica) which showed 5% divergence. Black-tailed and Hudsonian Godwits were thus clearly differentiated and the separate species status for the two taxa is validated. The Black-tailed Godwit is split into three subspecies on the basis of morphological differences. The present taxonomy of the species recognises three subspecies: L.l.islandica on Iceland, the Faroe islands and north-western Norway; L.l. limosa from England in the west to the western limits of the Altai mountains in the east; and L.l. melanuroides from lake Baikal eastwards to the Pacific Ocean. The three subspecies all have disjunct breeding ranges. All three subspecies described for the Black-tailed Godwit had unique haplotypes but the genetic distances were small (0.3–0.6%). Despite small genetic differences any substantial gene flow was not detected between any of the subspecies, as haplotypes were private to each subspecies. Thus, genetic variation within Black-tailed Godwits showed a clear geographic structure. This study found a high proportion of rare private haplotypes in three fringe populations of the nominate subspecies of the Black-tailed Godwit (L. l. limosa) where Godwits breed in low numbers, but no genetic variation at all in a sample from the Netherlands where Godwits are abundant. This suggests that Dutch Godwits may have been affected by a founder effect and/or been bottlenecked during its history.
Ghaemi, R. 2006. Shorebirds of the wetland of Gomishan, Iran. Wader Study Group Bull. 109: 102–105.
The first year-round monthly shorebird census of the wetland of Gomishan (Iran), in the SE corner of
the Caspian Sea, carried out in 1999 recorded 26 species with total numbers ranging from 130 in June to 10,358 in February. The site is shown to be of international importance for the Black-tailed Godwit, which was the most abundant species, with a peak count of 3,500 in September. The area is used during spring migration by 1480-2600 Godwits from February to April. Autumn migration numbers range form 2500-3500 birds during August to October. Few birds winter in the area, with numbers ranging from 48-545 during November and December. When January counts for five of the most abundant species are compared for 1994–2000, it appears that there is considerable variation between years. However, Black-tailed Godwit show a decreasing trend since 1997 when approximately 8000 birds were counted. A number of factors may be responsible for this including disturbance from fishing boat traffic as well as from both legal and illegal fishing and hunting. Raised water levels may also have reduced feeding opportunities for this species.
Lourenço, P.M. & Piersma, T. 2008. Changes in the non-breeding distribution of Continental Black-tailed Godwits Limosa limosa limosa over 50 years: a synthesis of surveys. Wader Study Group Bull. 115(2): 91–97.
Over the years a lot of information has been gathered regarding the migratory and wintering distribution of Black-tailed Godwits Limosa limosa. Much of this information is only available in the so-called “grey” literature. In this study data is presented of non-breeding count data for the continental race L. l. limosa covering the last fifty years. It is suggested that there have been important changes in the winter and spring-staging distribution and numbers of this now threatened population. The winter distribution covers a wide area from Senegal and Guinea-Bissau in the west, through Mali and Chad and extends into the Middle East as far as Iran. During spring, the most important staging sites are around the Mediterranean basin, with key areas in Iberia and France. Throughout the range, numbers have changed over time. Today, areas in West Africa, like Senegal, possibly Morocco and to some extent Guinea-Bissau have much lower numbers of godwits than 20 years ago, whereas in the Niger inland delta in Mali, lake Chad basin and north Cameroon numbers have remained more or less stable. Larger numbers of godwits now occur in southern Europe, Portugal and Spain; but the French wetlands have lost some of their past importance. The Gulf of Gabés in Tunesia, the Po river rice plantations in Italy and the Marais Poitevin and Valées Angevines in France also support significant numbers. Further east, wetlands of importance include Amvrakikos and the Messolonghi delta in Greece, as well as Kizilirmak and Akyatan Gölü in Turkey. The Persian Gulf, coast of Iran also appears to be a particularly significant wintering area, probably for birds belonging to the most easterly part of the breeding population.
Salim M., Porter R.& Rubec C. 2009. A summary of birds recorded in the marshes of southern Iraq, 2005–2008. In: Krupp F., Musselman L.J., Kotb M.M.A. & Weidig I. (Eds) Environment, Biodiversity and Conservation in the Middle East. Proceedings of the First Middle Eastern Biodiversity Congress, Aqaba, Jordan, 20–23 October 2008. BioRisk 3: 205–219.
The marshlands of Lower Mesopotamia (Iraq) witnessed severe draining programs during the late 1980s and early 2000s, which turned vast areas of the former water body into desert areas. New field surveys of birds and their habitats in the marshes of southern Iraq were launched in 2005. This has yielded new data on the status, distribution and habitat requirements of birds and other biota in Key Biodiversity Areas in Iraq from 2005 to 2008. This paper summarizes the bird data obtained in these surveys in the southern marshes, during which 159 species of birds were recorded; of these 34 are considered to be of conservation concern, including eight that are globally threatened. Black tailed Godwits were recorded in the winter months at 20 monitoring sites in southern Iraq during all years from 2005 to 2008. The highest count was 2010 individuals in the winter of 2008.
Melman, T.C.P, Schotman, A.G.M, Hunink, S. & de Snoo, G.R. 2008. Evaluation of meadow bird management, especially black-tailed godwit (Limosa limosa L.), in the Netherlands. Journal for Nature Conservation 16: 88-95.
Although the protection of Black-tailed Godwits is a key focus of Dutch nature conservation policy, management schemes (nature reserves and agri-environmental schemes) are not having the desired effect. This study examines the extent to which the disappointing results are related to suboptimal location of the managed sites. An exploring analysis was made using a GIS on the spatial overlap on a national scale between: (i) the gross area actually considered suitable for the black-tailed godwit (i.e. density >5 breeding pairs/100 ha); (ii) the area currently managed for meadow birds under an environmental management scheme; and, (iii) the area affected by various constraints (road traffic noise, landscape closure, excessive drainage and high predation pressure). For approximately 43% (31000 ha) of these grounds it appears that management effects might be hampered by the aforementioned constraints. Overall, the main constraining factors are predation (26%) and excessive drainage (23%). At 19% of the sites the landscape is not open enough, while another 19% are subject to traffic noise. Based on this sample, it seems likely that in the Netherlands as a whole only about 285,000 ha of the gross ‘meadow bird area’ (570,000 ha) actually qualifies as such. More attention should be paid to actual site suitability when nature targets are established and management contracts are approved and extended.
Gache, C. 2010. Bird fauna long-term monitoring in the Romanian lower Prut river basin. Travaux du Museum National d’Histoire Naturelle LIII: 287-302.
The Romanian Prut river valley has a length of ca. 742 km and lies on the border with Ukraine and the Republic of Moldova. Part of the valley is included in the Romanian Nature 2000 network. Human pressure is low but increasing. During the last 18 years the whole Romanian territory of the Prut River basin was surveyed several times covering more than 65 observatory stations following the qualitative and quantitative dynamic of the avifauna in the area. Counts were made during all ecological seasons using different methods. The area is hardly used during the breeding season but is an important stopover site for 5000-7000 Black-tailed Godwits.
Kuijper, D.P.J., Wymenga, E., van der Kamp, J. & Tanger, D. 2006. Wintering areas and spring migration of the Black-tailed Godwit. Bottlenecks and protection along the migration route. A&W rapport 820. Altenburg & Wymenga ecologisch onderzoek, Veenwouden.
This study presents a survey of wintering areas and spring staging sites and presents recommendations for an effective protection strategy. As soon as the breeding season ends Godwits migrate to their wintering areas in the Senegal delta, coastal region from Senegal to Guinea and the Inner-Niger delta in Mali. Godwits stay about 6-7 months from July/August onwards in their wintering quarters. Rice fields hold about 40% of the wintering population. Numbers has halved compared to the 1980’s except for Mali where the population is stable. This population mainly originates from the central European breeding population. Hunting and human disturbance seem to be no significant factor for the survival of Godwits in the winter range. From December onwards Godwits migrate north to their breeding grounds. The rice fields of Portugal and Spain contain the highest concentrations of birds. Up to 27% of the breeding population of Western Europe can be present at one moment. Two types of Godwits may be distinguished based on diet choice on different staging sites. The most numerous type maximizes time spent foraging on rice and fly from West Africa to rice fields in Portugal/Spain before flying to the Netherlands. The second type may mainly forage on invertebrates and flies to Morocco and France. Habitat changes in these countries have had a negative effect and may have contributed to a shift in staging sites. For the conservation of Black-tailed Godwits it is important to adopt a fly-way approach which includes the entire flyway and especially safe-guards crucial staging sites.
Kentie R., Senner N.R., Hooijmeijer J.C.E.W., Márquez-Ferrando R., Figuerola, J., Masero J.A., Verhoeven M.A. & Piersma T. 2016. Estimating the size of the Dutch breeding population of Continental Black-tailed Godwits from 2007–2015 using resighting data from spring staging sites. Ardea 114: 213–225.
Over the past 50 years, the population of Continental Black-tailed Godwits Limosa limosa limosa breeding of the East Atlantic Flyway has been in steep decline. This decline has previously been documented in trend analyses and six Netherlands-wide count-based population estimates, the last of which was completed in 1999. We provide an updated population size estimate and describe inter-annual fluctuations in the population between 2007 and 2015. To generate these estimates, we integrated a mark-recapture survival analysis with estimates of the densities of colour-marked individuals at migratory staging sites with known proportions of Continental and Icelandic L. l. islandica Black-tailed Godwits within a Bayesian framework. The use of these analytical techniques means that, in contrast with earlier efforts, our estimates are accompanied with confidence intervals, allowing us to estimate the population size with known precision. Using additional information on the breeding destination of 43 godwits equipped with satellite transmitters at Iberian staging areas, we found that 87% (75–95% 95% CI) of the nominate subspecies in the East Atlantic Flyway breed in The Netherlands. We estimated that the number of breeding pairs in The Netherlands has declined from 47,000 (38,000–56,000) pairs in 2007 to 33,000 (26,000–41,000) in 2015. Despite a temporary increase in 2010 and 2011, the population declined by an average of 3.7% per year over the entire period from 2007–2015, and by 6.3% from 2011–2015. We conclude that investing in an intensive demographic programme at a regional scale, when combined with targeted resightings of marked individuals elsewhere, can yield population estimates at the flyway scale.
Żmihorski M., Krupiński D., Kotowska D., Knape J., Pärt T. , Obłoza P., Berg Å., 2018. Habitat characteristics associated with occupancy of declining waders in Polish wet grasslands. Agriculture, ecosystems & environment 251: 236-243.
Populations of meadow waders have shown steep declines in Europe during recent decades. However, empirical evidence concerning habitat preferences of different species in east Europe is largely lacking. In this study we investigate occurrence of the Eurasian curlew (Numenius arquata), black-tailed godwit (Limosa limosa), common redshank (Tringa totanus) and northern lapwing (Vanellus vanellus) in 413 grassland plots (c. 50,000 ha in total) located in Polish lowland surveyed three times during spring of 2015 and 2016. Using hierarchical occupancy models corrected for imperfect detection we link local water conditions, forest cover and scattered trees and presence of cows and buildings with occurrence of waders. Presence of godwit positively correlated with flooding and wetness while negatively with drainage ditches and single trees. Redshank was positively associated with flooding and negatively with ditches and proximity to buildings. Lapwing was less often observed in proximity to buildings and at sites with numerous trees whereas curlews, showed no clear associations with any of the environmental variables investigated. Detectability of studied species (except godwit) was higher when corvids were present suggesting that species interactions may affect detection. Field survey conditions (e.g. time of day, number of visit) also contributed to detectability of all studied species. Our study suggest that water availability, including natural flooding, increases habitat quality for breeding waders, while single trees and farm buildings may reduce grassland availability for these species. Thus waders-oriented agri-environment subsidies, besides adjusting grassland management to breeding phenology, should also focus on wetness and openness of grasslands.
Van der Vliet R.E., van Dijk J. & Wassen M.J. 2010. How different landscape elements limit the breeding habitat of meadow bird species. Ardea 98: 203–209.
Meadow bird species in the Netherlands have shown a long-term decline in numbers. This has been generally attributed to agricultural intensification, but in addition an increase of disturbing elements may have played a role in the decline. In this review we compiled data from literature to explore to what extent breeding by meadow birds (Eurasian Oystercatcher Haematopus ostralegus, Northern Lapwing Vanellus vanellus, Black-tailed Godwit Limosa limosa) is limited by disturbing landscape elements. We considered elements that can be considered ‘view-obstructing’ (like trees or houses), and those that can be considered ‘flat’ (canal, road or railway). Our review shows that breeding birds keep a distance to both types of landscape elements, with distances ranging over 1 km for highways and village edges. Roads with high traffic intensity caused the largest disturbance. Eurasian Oystercatcher was most tolerant to the presence of landscape elements, and Black-tailed Godwit least tolerant.
Kahlert J., Clausen P., Hounisen J.P., Petersen, I.K. 2007. Response of breeding waders to agri-environmental schemes may be obscured by effects of existing hydrology and farming history. Journal of Ornithology 148: S287-S293 Supplement: 2.
The initiation of agri-environmental schemes (AES) to improve habitats for breeding waders may not show expected benefits in all situations. We show this, using results from a study of breeding waders on 469 grassland fields in the Danish Wadden Sea area. Numbers of breeding waders were not restored to levels of the recent past, even though Lapwings Vanellus vanellus, Black-tailed Godwits Limosa limosa and Redshanks Tringa totanus were drawn to wet permanent grasslands with AES. We had expected that more waders would be attracted by improved surface water retention during the breeding period due to the AES. However, AES were not introduced to all fields, and this measure did not dramatically change the water regime in part of the breeding fields. Furthermore, dry grasslands and fields that had been cultivated or drained before did not attract more waders, despite the introduction of the AES. The results suggest that the interplay between surface water retention and former farming history are important determinants of the habitat choice for breeding waders. The study emphasises the need for pre-defined success criteria, thorough analysis of the nature of the habitat and consideration of population processes before initiation of an AES, so that realistic management goals are defined and expected benefits can be achieved.
Kentie, R., Both C., Hooijmeijer J.C.E.W. & Piersma T. 2015. Management of modern agricultural landscapes increases nest predation rates in Black-tailed Godwits Limosa limosa. Ibis 157 (3): 614-625
Effective conservation of endangered species requires a solid understanding of the demographic causes of population change. Bird populations breeding on agricultural grasslands have declined because their preferred habitat of herb-rich meadows has been replaced by grassland monocultures. The timing of agricultural activities in these monocultural grasslands is critical, as they often coincide with the nesting phase of breeding birds. Here, we aim to identify the effect of habitat management and targeted nest protection on nest survival of Black-tailed Godwits Limosa limosa in the Netherlands, a population that has shown a 70% reduction in breeding population size since the 1970s. To protect nests in monocultures from destruction, farmers are paid to either delay mowing or leave a patch of unmown grass around the nest, a patch which in practice varied in size. In herb-rich meadows, which are typically managed for bird conservation purposes, mowing occurs after hatching. Nest survival declined as the season advanced, more steeply on monocultures than on meadows. Targeted nest protection was only partially successful, as nest predation was considerably higher on mown grassland monocultures with small unmown patches around the nest than in mown monocultures with large unmown patches and in unmown fields. Increased predator densities over the years have been suggested as an important cause of the trend towards lower nest survival, but here we show that nest survival was higher on herb-rich meadows than on monocultures, and similar to the 1980s. It thus seems that increased predator densities are an increased threat during the egg stage only if habitat quality is low. High-quality habitat in the form of herb-rich meadows therefore provides a degree of protection against predators.
Kentie, R., Both C., Hooijmeijer J.C.E.W. & Piersma T. 2014. Age-dependent dispersal and habitat choice in black-tailed godwits Limosa limosa limosa across a mosaic of traditional and modern grassland habitats. Journal of Avian Biology 45(4): 396-405.
Whether to disperse, and where to, are two of the most prominent decisions in an individual's life, with major consequences for reproductive success. We studied natal and breeding dispersal in the monogamous black-tailed godwit Limosa limosa limosa in the Netherlands, where they breed in agricultural grasslands. The majority of these grasslands recently changed from wet herb-rich meadows into well-drained grassland monocultures, on which godwits have a lower reproductive success. Here we examine habitat selection with a multistate mark-recapture analysis. Habitat transition probabilities between meadows and monocultures were estimated on the basis of 1810 marked chicks and 531 adults during seven years in a 8500 ha study area. Young and adult godwits may differ in habitat selection because: 1) adults may have gained experience from previous nest success where to settle, 2) younger individuals may find it harder to compete for the best territories. Both young and adults moved at a higher rate from the predominant monocultures to meadows than the other way around, thus actively selecting the habitat with better quality. However, dispersal distance of adults was not affected by previous nest success. The average dispersal distance from place of birth of godwits breeding for the first time was ten times larger than that of adult godwits. That godwits breeding in their second calendar year arrived and laid at similar dates and were equally able to select territories in areas with high breeding densities, suggests that young birds were not competitively inferior to adults. Although on monocultures reproduction is insufficient to maintain constant populations, birds sometimes moved from meadows to monocultures. This explains why even after 30 years of land-use intensification, godwits still breed in low-quality habitat. The adjustment to changing habitat conditions at the population level appears to be a slow process.
Groen N.M. 1993. Breeding site-tenacity and natal philopatry in the Black-tailed Godwit Limosa l. limosa. Ardea 81 (2): 107-113
Breeding site tenacity and natal philopatry have been studied in a marked population of Black-tailed Godwits. Distances between successive nesting locations in the investigated area have been measured for at least two years. These figures show a strong attachment of Godwits to previous nest sites. Breeding success, mate fidelity and quality of habitat are factors influencing and determining the level of breeding site tenacity. Breeding site tenacity and natal philopatry are male biased. These results are in agreement with the monogamous mating system of the Black-tailed Godwit. Management practice may contribute to breeding site tenacity by reducing agricultural activities on plots during the breeding season. This results in an increase of breeding success, one of the main factors inhibiting disappearance from former breeding sites.
Kentie, R., Hooijmeijer J.C.E.W., Trimbos K.B., Groen N.M. & Piersma T. 2013. Intensified agricultural use of grasslands reduces growth and survival of precocial shorebird chicks. Journal of Applied Ecology 50(1): 243-251
Intensification of agricultural use of grassland habitats has been linked to the declines of many farmland bird species, several of whom have been in decline for multiple decades despite agri-environmental schemes. In the Netherlands, where most grasslands have been transformed into well-drained monocultures managed for maximal dairy production, schemes that aim to protect nests from agricultural activities are the most popular. The cause of the failure of these schemes, however, seems poor recruitment of farmland birds. Using the black-tailed godwit Limosa limosa limosa as our model species, we tested the hypothesis underlying the most popular agri-environmental schemes that there are no differences in condition at hatch, growth, and apparent survival rates between chicks raised on monocultures compared with chicks from herb-rich meadows with high water tables, often managed, for the sake of grassland birds, in traditional ways. We also compare the growth rates from both habitat types with those of chicks from dairy farmland from 1976 to 1985, a time when population declines of godwits first became visible. Hatchling mass did not differ between chicks from herb-rich meadows and grassland monocultures, but chicks hatched on monocultures were on average 14-16% lighter at fledging, and had 4% smaller bills than chicks hatched on herb-rich meadows. The growth rates of female chicks hatched on herb-rich meadows were similar to those of chicks measured from 1976 to 1985. Males fledged lighter and smaller than females. Apparent survival during the first year of life for chicks hatched on herb-rich meadows was 2 center dot 5 times higher than that of chicks hatched on grassland monocultures. The apparent survival on herb-rich meadows seems sufficient for a stable population. Synthesis and applications: We found striking differences between chicks hatched on modern grassland monocultures and herb-rich meadows. That chicks hatched on monocultures had lower growth and survival rates than chicks on meadows indicates that these chicks suffer a higher risk of starvation and/or predation. These findings imply that the most often applied agri-environmental schemes (i.e. payments per clutch found and postponed mowing), are not effective. Instead, these schemes could even encourage maladaptive habitat choice. Conservation efforts should thus focus on the provision of herb-rich meadows with high groundwater tables.