Limosa Limosa Research Articles

Wetland salinity induces sex-dependent carry-over effects on the individual performance of a long-distance migrant

Salinization is having a major impact on wetlands and its biota worldwide. Specifically, many migratory animals that rely on wetlands are increasingly exposed to elevated salinity on their nonbreeding grounds. Experimental evidence suggests that physiological challenges associated with increasing salinity may disrupt self-maintenance processes in these species. Nonetheless, the potential role of salinity as a driver of ecological carry-over effects remains unstudied. Here, we investigated the extent to which the use of saline wetlands during winter – inferred from feather stable isotope values – induces residual effects that carry over and influence physiological traits relevant to fitness in black-tailed godwits Limosa limosa limosa on their northward migration. Overwintering males and females were segregated by wetland salinity in West Africa, with females mostly occupying freshwater wetlands. The use of these wetlands along a gradient of salinities was associated with differences in immune responsiveness to phytohaemagglutinin and sized-corrected body mass in godwits staging in southern Europe during northward migration – 3,000 km from the nonbreeding grounds – but in males only. These findings provide a window onto the processes by which wetland salinity can induce carry-over effects and can help predict how migratory species should respond to future climate-induced increases in salinity.

On the usefulness of prediction intervals for local species distribution model forecasts

The maps produced by species distribution models (SDMs) are increasingly used by decision-makers for supporting local and regional land-use as well as landscape planning issues. While ecologists generally are interested in large-scale patterns and the overall quality of SDMs, decision-makers and conservationists focus on the reliability of localized predictions relevant for specific projects. Here, we use the machine learning methods Random Forest and Quantile Regression Forest to predict local abundance of the black-tailed godwit Limosa limosa with prediction intervals, a measure of the probability that a future observation will lie between certain limits. Although the confidence intervals for local predictions are very narrow, the corresponding prediction intervals are very wide. Therefore, the actual numbers of the black-tailed godwit expected at a given point in the field may vary from virtually absent to high density. We conclude that practitioners should lower their expectations of maps based on the currently available SDMs and to be careful when utilizing them for supporting local management decisions.

British Ornithologists’ Union Union Medal

British Ornithologists’ Union Union Medal

Non-native predator control increases the nesting success of birds: American mink preying on wader nests

The ongoing decline of breeding wader populations in Europe has been mostly explained by habitat changes and the increasing impact of native predators, but the influence of non-native invasive predators has been neglected. A seven year study of the nesting success of the northern lapwing, common redshank and black-tailed godwit was carried out in Biebrza National Park in north-eastern Poland, alongside the American mink control programme, which was undertaken with low and high intensities of mink control. Indices of mink density, based on the percentage of floating rafts with mink tracks and the number of mink trapped per 100 trap-nights, declined with the increasing number of mink removed in consecutive years. In our model, the mink control and water level covariates explained most of the variation in daily nest survival rates. A decline in mink density led to increases in daily survival rates of nests and to the overall nesting success of all three wader species. Lower water levels led to a decrease in the overall daily survival rate (DSR) but this covariate affected DSR differently throughout the breeding season. These results demonstrate that predation by an introduced species, alongside low water levels during the nesting period, can limit the nesting success of multiple wader species, and that American mink should be considered as a key predator affecting ground-nesting wetland bird populations. Conservation plans for many wader species declining in numbers should include local reductions in mink populations in order to increase nesting success. Thus, intensive continuous mink control is recommended for important nesting refuges, utilising adaptive management to ensure control efforts remain sufficiently high.

Characterization of MHC class I in a long distance migratory wader, the Icelandic black-tailed godwit

The major histocompatibility complex (MHC) encodes proteins that are central for antigen presentation and pathogen elimination. MHC class I (MHC-I) genes have attracted a great deal of interest among researchers in ecology and evolution and have been partly characterized in a wide range of bird species. So far, the main focus has been on species within the bird orders Galliformes and Passeriformes, while Charadriiformes remain vastly underrepresented with only two species studied to date. These two Charadriiformes species exhibit striking differences in MHC-I characteristics and MHC-I diversity. We therefore set out to study a third species within Charadriiformes, the Icelandic subspecies of black-tailed godwits (Limosa limosa islandica). This subspecies is normally confined to parasite-poor environments, and we hence expected low MHC diversity. MHC-I was partially characterized first using Sanger sequencing and then using high-throughput sequencing (MiSeq) in 84 individuals. We verified 47 nucleotide alleles in open reading frame with classical MHC-I characteristics, and each individual godwit had two to seven putatively classical MHC alleles. However, in contrast to previous MHC-I data within Charadriiformes, we did not find any evidence of alleles with low sequence diversity, believed to represent non-classical MHC genes. The diversity and divergence of the godwits MHC-I genes to a large extent fell between the previous estimates within Charadriiformes. However, the MHC genes of the migratory godwits had few sites subject to positive selection, and one possible explanation could be a low exposure to pathogens.

Does wintering north or south of the Sahara correlate with timing and breeding performance in black-tailed godwits?

Migrating long distances requires time and energy, and may interact with an individual's performance during breeding. These seasonal interactions in migratory animals are best described in populations with disjunct nonbreeding distributions. The black‐tailed godwit (Limosa limosa limosa), which breeds in agricultural grasslands in Western Europe, has such a disjunct nonbreeding distribution: The majority spend the nonbreeding season in West Africa, while a growing number winters north of the Sahara on the Iberian Peninsula. To test whether crossing the Sahara has an effect on breeding season phenology and reproductive parameters, we examined differences in the timing of arrival, breeding habitat quality, lay date, egg volume, and daily nest survival among godwits (154 females and 157 males), individually marked in a breeding area in the Netherlands for which wintering destination was known on the basis of resightings. We also examined whether individual repeatability in arrival date differed between birds wintering north or south of the Sahara. Contrary to expectation, godwits wintering south of the Sahara arrived two days earlier and initiated their clutch six days earlier than godwits wintering north of the Sahara. Arrival date was equally repeatable for both groups, and egg volume larger in birds wintering north of the Sahara. Despite these differences, we found no association between wintering location and the quality of breeding habitat or nest survival. This suggests that the crossing of an important ecological barrier and doubling of the migration distance, twice a year, do not have clear negative reproductive consequences for some long‐distance migrants.

Metabolic plasticity for subcutaneous fat accumulation in a long-distance migratory bird traced by 2H2O.

The migrant black-tailed godwit (Limosa limosa) traditionally used natural wetlands in the Iberian Peninsula to prepare for migratory flights by feeding mainly in estuaries. In recent decades, this species has become increasingly dependent on rice fields, thereby relying on a plant-based diet for fuelling. Dietary fatty acids (FA) seem to be determinant to the composition of accumulated subcutaneous fat in migratory birds. It is still unclear whether metabolic plasticity allows for modification and/or synthesis of FA, contributing to a lipid profile that enables a successful migratory performance. Deuterated water was administered to captive black-tailed godwits submitted to two diets (fly larvae versus rice) and the incorporation of deuterium (2H) into subcutaneous triglycerides was analyzed by NMR. A recently developed localized biopsy method for sampling subcutaneous fat was employed with later successful release of all birds into the wild. The average chemical structure reflected mostly a mixture of saturated and monounsaturated 16- and 18-carbon FA, a profile frequently found in migrant birds. Significantly higher levels of polyunsaturated FA, as well as detectable levels of n-3 FA, were observed in fly-larvae-fed birds. Excess 2H-enrichments in FA revealed significantly higher rates of fractional de novo lipogenesis and FA desaturation capacity in rice-fed birds. This novel and non-lethal tracer method revealed the capacity of this species to alter its lipid metabolism to compensate for a poorer dietary lipid contribution. Because of its versatility, adapting this method to other scenarios and/or other migratory species is considered feasible and cost-effective.

BIRD AIRPORT— TIANJIN LINGANG BIRD SANCTUARY WETLAND PARK DESIGN

Each year more than 50 million birds make the return journey from the Antarctic reaches to the northern tip of the earth along the East Asian-Australasian Flyway (EAAF) seeking food and shelter. As one of the nine global north-south fly ways, the EAAF is now the world’s most threatened due to the loss of bird foraging habitat by coastal urbanization. One in five globally threatened water birds including the Black-Tailed Godwit fly the EAAF but they are suffering rapid declines in population. In a bid to increase critical bird habitat on the shores of the Bohai Bay in China, the Asian Development Bank encouraged the Port of Tianjin to embark upon an international design competition for a wetland bird sanctuary on a degraded land fill site in Lingang. McGregor Coxall won the first prize in the competition with a proposal of establishing the world’s first migratory “Bird Airport” — a 110-hectare wetland park and bird sanctuary. With some birds flying non-stop for more than 11,000 km and up to 10 days without food or water, the airport will be a crucial re-fueling and breeding stop on the EAAF.

Estimating the Size of the Dutch Breeding Population of Continental Black-Tailed Godwits from 2007–2015 Using Resighting Data from Spring Staging Sites

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...

Nuclear power and coastal birds: Predicting the ecological consequences of warm-water outflows

Local alteration of species abundance in natural communities due to anthropogenic impacts may have secondary, cascading effects on species at higher trophic levels. Such effects are typically hard to single out due to their ubiquitous nature and, therefore, may render impact assessment exercises difficult to undertake. Here we describe how we used empirical knowledge together with modelling tools to predict the indirect trophic effects of a future warm-water outflow on populations of shorebirds and wildfowl. Of the main potential benthic prey used by the birds in this instance, the clam Macoma balthica was the only species suspected to be adversely affected by a future increase of temperature. Various scenarios of decreases in prey energy content, simulating various degrees of temperature increase, were tested using an individual-based model, MORPH, in order to assess the effects on birds. The survival and body condition of eight of the 10 bird species modelled, dunlin, ringed plover, turnstone, redshank, grey plover, black-tailed godwit, oystercatcher and shelduck were shown to be not influenced even by the most conservative prey reduction scenarios. Most of these species are known to feed primarily on polychaete worms. For the few bivalve-feeding species, the larger size-classes of polychaete worms were predicted to be a sufficient alternative food. Only knot was predicted to have a lower survival under the two worst case scenario of decreased M. balthica energy content. We believe that this is the first time such predicted cascade effects from a future warm-water outflow have been shown.

Effects of grass field margin management on food availability for Black-tailed Godwit chicks

Over the last six decades, populations of wader species like the Black-tailed Godwit (Limosa limosa) have sharply decreased in the Netherlands. Agricultural intensification has led to reduced habitat quality for meadow birds. As a consequence, reproductive success has declined. One of the main drivers of this decline in reproductive success is reduced food availability for meadow bird chicks. Agri-environment schemes (AES), designed to halt this decline, have so far been insufficient. Most of these AES focus on entire fields, but recent research suggests that differences in suitability exist within fields. Grass field margins may be more suitable for meadow bird chicks than the center of intensively managed grass lands. To improve existing meadow bird AES it could be beneficial to implement additional management in field margins of intensively managed grass fields. An already existing type of field margin AES with additional management is the botanical field margin. Here, we evaluate four different types of field margin management, including botanical field margins, focusing on aerial insects (an important part of the diet of Black-tailed Godwit chicks and Redshank chicks) in field centers and margins. Grass field margins contained more large aerial insects than field centers and, more importantly, additional management of the grass field margin increased the number of aerial insects in the margin. We conclude that combining meadow bird AES and botanical field margin management may enhance meadow bird food availability and improve the efficacy of AES.

Recent northward expansion of breeding Black-tailed Godwits <em>Limosa limosa</em> in NW Russia

Recent northward expansion of breeding Black-tailed Godwits <em>Limosa limosa</em> in NW Russia

Facultative Interspecific Brood Parasitism in Colonial Breeding Waterbirds in Biebrza National Park, Poland

Abstract. Interspecific brood parasitism occurs when the eggs of one species are laid in the nest of a different species, but evidence of this phenomenon is scarce. Facultative interspecific brood parasitism has been described in Charadriiformes. However, to our knowledge, our study provides the first documentation of facultative interspecific brood parasitism in the colonially breeding species we studied. The factors affecting its frequency in relation to colony species composition, nest density, and period of the breeding season was analyzed. Between 2006 and 2012, we monitored 2,493 nests of five species: Northern Lapwing (Vanellus vanellus; n = 745), Common Redshank (Tringa totanus; n = 467), Black-tailed Godwit (Limosa limosa; n = 237), Black-headed Gull (Chroicocephalus ridibundus; n = 932) and Common Tern (Sterna hirundo; n = 112). Facultative interspecific brood parasitism was observed in 1.3% of all nests. Typically, a single egg was laid in a host nest (59.4% of parasitized nests), and a maximum...

The Flight of Birds and Other Animals

Methods of observing birds in flight now include training them to fly under known conditions in wind tunnels, and fitting free-flying birds with data loggers, that are either retrieved or read remotely via satellite links. The performance that comes to light depends on the known limitations of the materials from which they are made, and the conditions in which the birds live. Bird glide polars can be obtained by training birds to glide in a tilting wind tunnel. Translating these curves to power required from the flight muscles in level flight requires drag coefficients to be measured, which unfortunately does not work with bird bodies, because the flow is always fully detached. The drag of bodies in level flight can be determined by observing wingbeat frequency, and shows CD values around 0.08 in small birds, down to 0.06 in small waders specialised for efficient migration. Lift coefficients are up to 1.6 in gliding, or 1.8 for short, temporary glides. In-flight measurements can be used to calculate power curves for birds in level flight, and this has been applied to migrating geese in detail. These typically achieve lift:drag ratios around 15, including allowances for stops, as against 19 for continuous powered flight. The same calculations, applied to Pacific Black-tailed Godwits which start with fat fractions up to 0.55 at departure, show that such birds not only cross the Pacific to New Zealand, but have enough fuel in hand to reach the South Pole if that were necessary. This performance depends on the “dual fuel” arrangements of these migrants, whereby they use fat as their main fuel, and supplement this by extra fuel from burning the engine (flight muscles), as less power is needed later in the flight. The accuracy of these power curves has never been checked, although provision for stopping the bird, and making these checks at regular intervals during a simulated flight was built into the original design of the Lund wind tunnel. The Flight programme, which does these comparisons, also had provision for including contributions due to extracting energy from the atmosphere (soaring), or intermittent bounding flight in small birds (Passerines). It has been known for some time that the feathered surface allows the bird to delay or reverse detachment of the boundary layer, although exactly how this works remains a mystery, which might have practical applications. The bird wing was in use in past times, when birds were still competing with pterosaurs, although these had less efficient wings. The birds that survived the extinction that killed the pterosaurs and dinosaurs have (today) an automatic spherical navigator, which enables them to cross the Pacific and find New Zealand on the other side. Bats have never had such a device, and pterosaurs probably did not either. Animals, when seen from a zoological point of view, are adapted to whatever problems they had to deal with in earlier times.

Plasma metabolites correlate with weekly body mass changes in migrating black-tailed Godwits Limosa limosa feeding on different diets

The study of variations in plasma metabolite profiles has emerged as a useful physiological tool to assess fuel deposition rates from a single blood sample. Diet may be a key factor in the study of refueling patterns in long-distance migratory birds, but the potential confounding effect of diet on the conclusions drawn from plasma metabolites has rarely been considered. Here, we assessed whether plasma metabolite levels correlate with the weekly increase in body mass of migrating Black-tailed Godwits Limosa limosa, a medium–large shorebird, feeding on two natural diets (insectivorous vs. granivorous) during the refueling period. We found that glycerol and triglycerides successfully explained the weekly natural change in body mass of Black-tailed Godwits. Although the diet type contributed to the change in body mass, all interactions between plasma metabolites and diet treatment were non-significant. Our results support the use of plasma metabolite profiling to predict body mass changes on a long-term (weekly) scale in medium–large birds.

Food Availability for Meadow Bird Families in Grass Field Margins

Agricultural intensification in grasslands has led to the decline of meadow bird populations in The Netherlands in the last 60 years. Habitat for meadow bird chicks has declined in quality and quantity, thereby reducing food availability. Agri-environment schemes (AES) to halt the decline in meadow bird numbers have thus far been insufficient. These AES are on the level of entire fields, but recent research suggests that margins of fields may be more suitable chick habitat than centres of fields. Therefore, it could be productive to specifically target grass field margins as part of meadow bird AES. Our study examined the differences in food availability for meadow bird families in different portions of a grass field. Invertebrates were sampled in different locations on the field and results were compared to known dietary preferences of four species of meadow bird chicks. We show strong differences in food availability within fields, depending on meadow bird species. The preferred prey species of chicks of Black-tailed Godwit Limosa limosa and Redshank Tringa totanus predominantly occurred in field margins, whereas those of Oystercatcher Haematopus ostralegus chicks were found mostly in the main part of the field. The prey species of Northern Lapwing Vanellus vanellus chicks showed no clear pattern within fields. We conclude that food availability within a field differs spatially between meadow bird species. Particularly for Black-tailed Godwit and Redshank, grass field margins constitute an important part of the field. Therefore, specific management to further enhance food availability in these margins may constitute an important addition to the existing mosaic approach.

When Siberia came to the Netherlands: the response of continental black-tailed godwits to a rare spring weather event.

1. Extreme weather events have the potential to alter both short- and long-term population dynamics as well as community- and ecosystem-level function. Such events are rare and stochastic, making it difficult to fully document how organisms respond to them and predict the repercussions of similar events in the future. 2. To improve our understanding of the mechanisms by which short-term events can incur long-term consequences, we documented the behavioural responses and fitness consequences for a long-distance migratory bird, the continental black-tailed godwit Limosa limosa limosa, resulting from a spring snowstorm and three-week period of record low temperatures. 3. The event caused measurable responses at three spatial scales - continental, regional and local - including migratory delays (+19 days), reverse migrations (>90 km), elevated metabolic costs (+8·8% maintenance metabolic rate) and increased foraging rates (+37%). 4. There were few long-term fitness consequences, however, and subsequent breeding seasons instead witnessed high levels of reproductive success and little evidence of carry-over effects. 5. This suggests that populations with continued access to food, behavioural flexibility and time to dissipate the costs of the event can likely withstand the consequences of an extreme weather event. For populations constrained in one of these respects, though, extreme events may entail extreme ecological consequences.

Predicting the effect of invertebrate regime shifts on wading birds: Insights from Poole Harbour, UK

Regime shifts in benthic invertebrates within coastal ecosystems threaten the survival of wading birds (Charadrii). Predicting how invertebrate regime shifts will affect wading birds allows conservation management and mitigation measures to be implemented, including protection of terrestrial feeding areas. An individual-based model was used to investigate the impact of regime shifts on wading birds through their prey (marine worms and bivalves) in the estuarine system Poole Harbour, (UK). The model predicted the number of curlew (Numenius arquata), oystercatcher (Haematopus ostralegus), black-tailed godwit (Limosa limosa), redshank (Tringa totanus) and dunlin (Calidris alpina) supported in the Harbour during the non-breeding season (autumn and winter months). The most dramatic declines in bird numbers were for regime shifts that reduced the abundance of the largest invertebrates, particularly marine worms. The least adaptable bird species (those with the most restrictive diets) were unable to compensate by consuming other prey. Generally, as birds adapt to changes by switching to alternative prey species and size classes, changes in invertebrate size and species distribution do not necessarily affect the number of birds that the Harbour can support. Our predictions reveal a weakness in using birds as indicators of site health and invertebrate regime shifts. Differences in bird populations would not necessarily be detected by standard survey methods until extreme changes in invertebrate communities had occurred, potentially beyond the point at which these changes could be reversed. Therefore, population size of wading birds should not be used in isolation when assessing the conservation status of coastal sites.

Migration distance and breeding latitude correlate with the scheduling of pre-alternate body moult: a comparison among migratory waders

Moult is an important maintenance activity that should be carefully timed within the annual cycle. Many birds perform a pre-alternate moult of body feathers some time prior to the breeding season. In migrants, the timing of the pre-alternate moult coincides with the migration from wintering to breeding areas. In this study, we used visual plumage scores collected on the Continental Black-tailed Godwit Limosa limosa limosa in Portugal and The Netherlands to establish that the pre-alternate body moult of these birds during the northward migration between West Africa and The Netherlands takes place only in staging areas in the Iberian peninsula from late January to late February. A comparison of the moult strategy of these godwits with that of 20 other migratory wader populations (13 species) revealed that the former had a rather uncommon moult schedule which was more characteristic of populations with rather short migrations that breed at lower latitudes. We argue that this unusual moult schedule can be explained by a combination of ecological opportunity and proximate and ultimate trade-offs (hormonal incompatibly and maximization of plumage quality vs. time spent on migration, respectively).

Modeling direct and indirect climate change impacts on ecological networks: a case study on breeding habitat of Dutch meadow birds

Context Climate change can directly affect habitats within ecological networks, but may also have indirect effects on network quality by inducing land use change. The relative impact of indirect effects of climate change on the quality of ecological networks currently remains largely unknown. Objectives The objective of this study was to determine the relative impact of direct and indirect effects of climate change on a network of breeding habitat of four meadow bird species (Black-tailed godwit, Common redshank, Eurasian oystercatcher and Northern lapwing) in the Netherlands. Methods Habitat models were developed that link meadow bird breeding densities to three habitat characteristics that are sensitive to environmental change (landscape openness, land use and groundwater level). These models were used to assess the impact of scenarios of landscape change with and without climate change on meadow bird breeding habitat quality for a case study area in the peat meadow district of the Netherlands. Results All scenarios led to significantly reduced habitat quality for all species, mainly as a result of conversion of grassland to bioenergy crops, which reduces landscape openness. Direct effects of climate change on habitat quality were largely absent, indicating that especially human adaptation to climate change rather than direct effects of climate change was decisive for the degradation of ecological network quality for breeding meadow birds. Conclusions We conclude that scenario studies exploring impacts of climate change on ecological networks should incorporate both land use change resulting from human responses to climate change and direct effects of climate change on landscapes.