Avian migration

Many species travel in highly organized groups 1-3 . The most quoted function of these configurations is to reduce energy expenditure and enhance locomotor performance of individuals in the assemblage 4-11 . The distinctive V formation of bird flocks has long intrigued researchers and continues to attract both scientific and popular attention . The well-held belief is that such aggregations give an energetic benefit for those birds that are flying behind and to one side of another bird through using the regions of upwash generated by the wings of the preceding bird 4,7,9-11 , although a definitive account of the aerodynamic implications of these formations has remained elusive.

Recent advances in spring arrival dates have been reported in many migratory species but the mechanism driving these advances is unknown. As population declines are most widely reported in species that are not advancing migration, there is an urgent need to identify the mechanisms facilitating and constraining these advances. Individual plasticity in timing of migration in response to changing climatic conditions is commonly proposed to drive these advances but plasticity in individual migratory timings is rarely observed. For a shore-bird population that has significantly advanced migration in recent decades, we show that individual arrival dates are highly consistent between years, but that the arrival dates of new recruits to the population are significantly earlier now than in previous years. Several mechanisms could drive advances in recruit arrival, none of which require individual plasticity or rapid evolution of migration timings. In particular, advances in nest-laying dates could result in advanced recruit arrival, if benefits of early hatching facilitate early sub-sequent spring migration. This mechanism could also explain why arrival dates of short-distance migrants, which generally return to breeding sites earlier and have greater scope for advance laying, are advancing more rapidly than long-distance migrants.

Approximately two thirds of migratory songbirds in eastern North America negotiate the Gulf of Mexico (GOM), where inclement weather coupled with no refueling or resting opportunities can be lethal. However, decisions made when navigating such features and their consequences remain largely unknown due to technological limitations of tracking small animals over large areas. We used automated radio telemetry to track three songbird species (Red-eyed Vireo, Swainson’s Thrush, Wood Thrush) from coastal Alabama to the northern Yucatan Peninsula (YP) during fall migration. Detecting songbirds after crossing ∼1,000 km of open water allowed us to examine intrinsic (age, wing length, fat) and extrinsic (weather, date) variables shaping departure decisions, arrival at the YP, and crossing times. Large fat reserves and low humidity, indicative of beneficial synoptic weather patterns, favored southward departure across the Gulf. Individuals detected in the YP departed with large fat reserves and later in the fall with profitable winds, and flight durations (mean = 22.4 h) were positively related to wind profit. Age was not related to departure behavior, arrival, or travel time. However, vireos negotiated the GOM differently than thrushes, including different departure decisions, lower probability of detection in the YP, and longer crossing times. Defense of winter territories by thrushes but not vireos and species-specific foraging habits may explain the divergent migratory behaviors. Fat reserves appear extremely important to departure decisions and arrival in the YP. As habitat along the GOM is degraded, birds may be limited in their ability to acquire fat to cross the Gulf.

1.
Given the allometric scaling of thermoregulatory capacity in birds, and the cold and exposed Arctic environment, it was predicted that Arctic-breeding shorebirds should incur high costs during incubation. Using doubly labelled water (DLW), daily energy expenditure (DEE) during incubation was measured in eight shorebird species weighing between 29 and 142 g at various sites in the Eurasian and Canadian High Arctic. The results are compared with a compilation of similar data for birds at lower latitudes.
2.
There was a significant positive correlation between species average DEE and body mass (DEE (kJ day−1) = 28·12 BM (g)
0·524, r2= 0·90). The slopes of the allometric regression lines for DEE on body mass of tundra-breeding birds and lower latitude species (a sample mostly of passerines but including several shorebirds) are similar (0·548 vs 0·545). DEE is about 50% higher in birds on the tundra than in temperate breeding areas.
3.
Data for radiomarked Red Knots for which the time budgets during DLW measurements were known, indicated that foraging away from the nest on open tundra is almost
twice as costly as incubating a four-egg clutch.
4.
During the incubation phase in the High Arctic, tundra-breeding shorebirds appear to incur among the highest DEE levels of any time of the year. The rates of energy
expenditure measured here are among the highest reported in the literature so far, reaching inferred ceilings of sustainable energy turnover rates.

Recently, a shift in preen wax composition, from lower molecular weight monoesters to higher molecular weight diesters, was described for individuals of a sandpiper species (red knot, Calidris canutus) that were about to leave for the tundra breeding grounds. The timing of the shift indicated that diester waxes served as a quality signal during mate choice. Here, this hypothesis is evaluated on the basis of a survey of preen wax composition in 19 sandpiper species. All of these species showed the same shift observed in the high-Arctic breeding red knots. As the shift also occurred in temperate breeding species, it is not speciŽ c to tundra-breeding sandpipers. Both sexes produced the diester waxes during the incubation period until hatching, in addition to the short period of courtship, indicating that diesters’ functions extend beyond
that of a sexually selected ‘make-up’. The few non-incubating birds examined (males of curlew sandpipers (C. ferruginea) and ruffs (Philomachus pugnax)) had the lowest likelihood of secreting diesters, indicating a functional role for diester preen waxes during incubation. We propose that diester preen waxes enhance olfactory crypsis at the nest.

... Wiley-Liss, New York, pp 632-638 Gwinner E (1996) Circadian and circannual programmes inavian migration. ... A field experiment on stonechats in tropical Africa.) Biol Rhythm 17: 171-189 Gwinner E, Schwabt-Benzinger I, Schwabl H, Dittami J (1993) Twenty-four hour ...

In the course of each spring, two subspecies of knots Calidris canutus (islandica wintering in Europe and breeding in the Nearctic, and canutus wintering in west Africa and breeding in Siberia), stage in the international Wadden Sea before their northward flights to the arctic breeding grounds. In March-April islandica-knots predominantly use the intertidal flats in the western part of the Wadden Sea in The Netherlands (canutus is still in west Africa). In May both subspecies use the eastern part of the Wadden Sea in Schleswig-Holstein, Germany only. We studied these knots in core areas at both ends of the Wadden Sea in 1990, to examine whether the absence of knots in the western Wadden Sea in May is related to food res6urces or to other factors connected with the energy budget of these long-distance migrants. Islandica-knots in March-April in The Netherlands and canutus-knots in May in Germany had similar diets and showed similar size selection of their major bivalve prey Macoma balthica, giving the possibility for indirect competitive interactions. Knots spent more time feeding per day in Germany. The harvestable biomass of Macoma was of comparable magnitude in both parts of the Wadden Sea in May. That knots always leave the western Wadden Sea in late April is, therefore, not a direct response to prey depletion. If Macoma always subsides earlier in the year in the western part of the Wadden Sea than in the east as in 1990, the knots' absence in the west may represent the riding of an eastward wave of good feeding conditions resulting from longitudinal variation in bivalve-prey biology. At least for canutus, the reliance in May on the eastern Wadden Sea may (additionally?) represent early movements - at relatively low body masses - towards the breeding areas to gain the benefits of a small saving on the cost and time of travel, and of being closer to the weather systems that may help their flight into the breeding areas

The fuelling performance of long-distance migrants at staging areas indicates local conditions and determines the viability of migration routes. Here we present a first case study where long-term fuelling performance was documented along two migration routes with differential population trends. Ruffs (Philomachus pugnax) are shorebirds of inland freshwater wetlands that migrate from the sub-Saharan wintering grounds, via Europe, to the northern Eurasian breeding grounds. Assessments from 2001 to 2008 of fuelling during northward migration at the major western and eastern staging site revealed that daily mass gain rates steeply declined across years in the grasslands for dairy production in Friesland, The Netherlands, and remained constant in the Pripyat floodplains in Belarus, 1500 km further east. Migrants in Friesland decreased from 2001 to 2010 by 66%, amounting to a loss of 21,000 individuals when counts were adjusted for length of stay as determined by resightings. In the same period numbers in Pripyat increased by 12,000. Ruffs individually ringed in Friesland were resighted in subsequent springs at increasingly eastern sites including Pripyat. Our results corroborate published evidence for an eastward redistribution of Arctic breeding ruffs and suggest that the decreasing fuelling rates in the westernmost staging area contribute to this redistribution. The shift implies that responses occur within a single generation. The hypothesis that the choice of route during northward migration may be driven by food availability can now be tested by creating greater areas of wet grasslands in Friesland. When local staging conditions improve we predict that ruffs will make the reverse shift.

There are concerns that novel structures might displace protected species, facilitate the spread of non-indigenous species, or modify native habitats. It is also predicted that ocean warming and the associated effects of climate change will significantly increase biodiversity loss within coastal regions. Resilience is to a large extent influenced by the magnitude of dispersal and level of connectivity within and between populations. Therefore it is important to investigate the distribution and ecological significance of novel and artificial habitats, the presence of protected and alien species and potential vectors of propagule dispersal. The legacy of solar salt-making in tropical and warm temperate regions is regionally extensive areas of artificial hypersaline ponds, canals and ditches. Yet the broad-scale contribution of salt-working to a network of benthic biodiversity has not been fully established. Artisanal, abandoned and historic salt-working sites were investigated along the Atlantic coast of Europe between southern England (50 N) and Andalucía, Spain (36 N). Natural lagoons are scarce along this macrotidal coast and are vulnerable to environmental change; however it is suspected that avian propagule dispersal is important in maintaining population connectivity. During bird migration periods, benthic cores were collected for infauna from 70 waterbodies across 21 salt-working sites in 5 coastal regions. Bird ringing data were used to investigate potential avian connectivity between locations. Lagoonal specialist species, some of international conservation importance, were recorded across all regions in the storage reservoirs and evaporation ponds of continental salinas, yet few non-indigenous species were observed. Potential avian propagule transport and connectivity within and between extant salt-working sites is high and these artificial habitats are likely to contribute significantly to a network of coastal lagoon biodiversity in Europe.

Physical exertion during growth can affect ultimate size and density of skeletal structures. Such changes from different exercise regimes may explain morphological differences between groups, such as those exhibited by lesser snow geese (Chen caerulescens caerulescens; hereafter snow geese) foraging in southwest Louisiana. In rice-prairie habitats (hereafter rice-prairies), snow geese bite off or graze aboveground vegetation, whereas they dig or grub for subterranean plant parts in adjacent coastal marshes. Grubbing involves considerably more muscular exertion than does grazing. Thus, we hypothesized that rates of bone formation and growth would be lower for juveniles wintering in rice-prairies than those in coastal marshes, resulting in smaller bill and skull features at adulthood. First, we tested this exertion hypothesis by measuring bills, skulls, and associated musculature from arrival to departure (November–February) in both habitats in southwest Louisiana, using both banded birds and collected specimens. Second, we used the morphological data to test an alternative hypothesis, which states that smaller bill dimensions in rice-prairies evolved because of hybridization with Ross's geese (C. rossii). Under the exertion hypothesis, we predicted that bill and skull bones of juveniles would grow at different rates between habitats. However, we found that bill and skull bones of juveniles grew similarly between habitats, thus failing to support the exertion hypothesis. Morphometrics were more likely to differ by sex or change with sampling date than to differ by habitat. We predicted that significant, consistent skewness toward smaller birds could indicate hybridization with Ross's geese, but no skewness was observed in our morphological data, which fails to support the hybridization hypothesis. Further research is needed to clarify whether snow geese wintering in Louisiana represent a single polymorphic population that segregates into individually preferred habitats, which we believe at present to be more likely as an explanation than two ecologically and spatially distinct morphotypes. K E Y W O R D S bill size, body size, foraging exertion, habitat selection, introgressive hybridization, morphotypes

The paper presents an evaluation of subfossil bird bones from archaeological and geological sites in Europe that shows that birds of the genus Pelecanus occurred far out of their present range between 7.4 and 5.0 ka BP in the Danish archipelago. Additionally, from other northwestern European regions mid-Holocene records of pelicans are known. However, due to morphological similarities there are difficulties in species identification.
In this paper ancient DNA barcoding techniques were used to clarify the species assignment of one of these records for the first time. Our results show that the bone derives from Dalmatian pelican Pelecanus crispus , a species that today breeds in 15 colonies in the eastern Mediterranean. This species identification is especially remarkable since the Dalmatian pelican is known to be less migratory. We demonstrate that the appearance and disappearance of pelicans in northwestern Europe coincide with climate parameters, since all records fall within warm periods. This applies for the larger group of Danish records during the Holocene thermal maximum in northern Europe as well as for two more groups of records from central Europe and Britain dating to 1.9 and 0.8 ka ago. Recent ecological research on the Dalmatian pelican shows that the species seems to profit from the modern climate changes and is starting to expand its range. Our paper documents that under special circumstances short-distance migrant birds are also able to expand their ranges to areas far outside of the former distribution areas. Finally, the Dalmatian pelican is presented as an indicator species reflecting special climate conditions.
The present study demonstrates not only the possibility to recover avian DNA from at least 7 ka old bones, but the relevance of such genetic analysis in combination with archaeological data, particularly if bones could not be assigned to species level by morphological features. In such cases, aDNA is shown as a valuable tool for the reconstruction of the avifauna of the past.

Despite benefits of using light-sensitive geolocators to track animal movements and describe patterns of migratory connectivity, concerns have been raised about negative effects of these devices, particularly in small species of aerial insectivore. Geolocators may act as handicaps that increase energetic expenditure, which could explain reported effects of geolocators on survival. We tested this ‘Energetic Expenditure Hypothesis’ in 12 populations of tree swallows (Tachycineta bicolor) and barn swallows (Hirundo rustica) from North America and Europe, using measurements of corticosterone from feathers (CORTf) grown after deployment of geolocators as a measure of physiology relevant to energetics. Contrary to predictions, neither among- (both species) nor within-individual (tree swallows only) levels of CORTf differed with respect to instrumentation. Thus, to the extent that CORTf reflects energetic expenditure, geolocators apparently were not a strong handicap for birds that returned post-deployment. While this physiological evidence suggests that information about migration obtained from returning geolocator-equipped swallows is unbiased with regard to levels of stress, we cannot discount the possibility that corticosterone played a role in reported effects of geolocators on survival in birds, and suggest that future studies relate corticosterone to antecedent factors, such as reproductive history, and to downstream fitness costs.

In migratory species, sexual size dimorphism can mean differing energetic requirements for males and females. Differences in the costs of migration and in the environmental conditions occurring throughout the range may therefore result in sex-biases in distribution and resource use at different spatial scales. In order to identify the scale at which sexual segregation operates, and thus the scale at which environmental changes may have sex-biased impacts, we use range-wide tracking of individually color-ringed Icelandic black-tailed godwits (Limosa limosa islandica) to quantify sexual segregation at scales ranging from the occupation of sites throughout the non-breeding range to within-site differences in distribution and resource use.
Throughout the range of this migratory shorebird, there is no evidence of large-scale sex differences in distribution during the non-breeding season. However, the sexes differ in their selection of prey types and sizes, which results in small-scale sexual segregation within estuaries. The scale of sexual segregation therefore depends on the scale of variation in resource distribution, which, in this system, is primarily within estuaries. Sexual segregation in within-site distribution and resource use means that local-scale anthropogenic impacts on estuarine benthic prey communities may disproportionately affect the sexes in these migratory shorebirds.

We studied phenology, staging time and refuelling in Broad-billed Sandpipers Limicola falcinellus stopping over during spring migration in the Sivash (Black Sea, Ukraine) in May 1991–94. In the study area, peak staging numbers of 2000–2500 individuals occurred in the third week of May. In May 1993, 460 birds were marked with a yellow dye and 126 of these were colour-ringed. Before 28 May no departure of birds dyed yellow could be detected; by 3 June all birds had departed. Colour-ringed adults in mid May 1993 staged for a minimum of 8.2 days. After the observed departure of large flocks (24 May and later) the staging time of colour-ringed birds decreased significantly with body mass at the time of capture. Of birds mist-netted in 1991–94, 99.3% were in full summer plumage and 89% were adults. In second-year birds, fuel deposition rate (measured between individuals) was 0.44 g/day. In adults caught from early May to 24 May, overall fuel deposition rate was 1.04 g/day (3.4% of lean body mass). Mean adult body mass in early May was 34.8 g, increasing to 45.5 g after 24 May. Estimated body mass at departure was 51 g. Departure body mass and flight range estimates suggest that although birds refuelled quickly, fuel loads are only just sufficient for an unbroken flight to Scandinavia and the Kola Peninsula. We suggest that Broad-billed Sandpipers use the Sivash as a crucial final take-off stopover site, and that they follow a ‘jumping’ migration strategy, performed under narrow time constraints.

Birds breeding in cold environments regularly have to interrupt incubation to forage, causing a trade-off between two mutually exclusive behaviours. Earlier studies showed that uniparental Arctic sandpipers overall spend less time incubating their eggs than biparental species, but interspecific differences in size and ecology were potential confounding factors. This study reports on a within-species comparison of breeding schedules and metal egg temperatures in uni- and biparental sanderlings (Calidris alba) in Northeast Greenland in relation to ambient temperature. We recorded incubation schedules with nest temperature loggers in 34 sanderling clutches (13 uniparentals, 21 biparentals). The temperature of a metal egg placed within the clutch of 17 incubating birds (6 uniparentals, 9 biparentals) was measured as an indicator of the heat put into eggs. Recess frequency, recess duration and total recess time were higher in uniparentals than in biparentals and positively correlated with ambient temperatures in uniparentals only. Uniparental sanderlings maintained significantly higher metal egg temperatures during incubation than biparentals (1.4uC difference on average). Our results suggest that uniparental sanderlings compensate for the lower nest attendance, which may prolong the duration of the incubation period and negatively affect the condition of the hatchlings, by maintaining a higher heat flux into the eggs.

We studied the food and feeding ecology of Red Knots Calidris canutus rufa on an area of rocky flat, or restinga, near San Antonio Oeste in the northwest of Golfo San Matias, Provincia de Rio Negro, Argentina in March 1992. These Red Knots are on their way north, from "wintering" areas in Tierra del Fuego (Argentina and Chile) to the arctic breeding grounds in Canada. Three waves, each containing 5000-12,000 Knots, moved throughthe area. On the restinga they fed on banks of the small mussel Brachidontes rodriguezi, virtually the only prey taken.Variably sized( 1-28 mm) Brachidontes of which those between 5 and 20 mm were eaten (8-12 mm long mussels being positively selected), occurred in high biomass densities( 23-117 g ash-free dry mass [AFDM]/m2). Due to its abundance, visibility,ease of detachment, slender shell form, and relatively weak shell, Brachidontes appear very suitable prey for Red Knots. Red Knots produced about 0.42 droppings/min. On the basis of a biomass equivalent of the droppings of approximately 62 mg AFDM, for conditions of balance (shell mass in = shell mass out) the intake rate was estimated at 0.433 mg AFDM/s. Making a few more assumptions, this translated in to a net intake rate of 2.81 W, which would allow for a fat deposition rate of less than a gram of fat per day. Using more optimistic estimates o f the various parameters in the energy budget model, a fat deposition rate of 5 g could be achieved. This is the order of magnitude predicted for Red Knots staging at San Antonio Oeste for 6-8 d and refuelling for the 1700 km long flight to the next known major staging area in southern Brazil.

A novel migratory polymorphism evolved within the last 60 years in blackcaps (Sylvia atricapilla) breeding sympatrically in southwestern Germany. While most individuals winter in the traditional areas in the Mediterranean, a growing number of blackcaps started migrating to Britain instead. The rapid microevolution of this new strategy has been attributed to assortative mating and better physical condition of birds wintering in Britain. However, the isolating barriers as well as the physical condition of birds are not well known. In our study, we examined whether spatial isolation occurred among individuals with distinct migratory behaviour and birds with different arrival dates also differed in physical and genetic condition. We caught blackcaps in six consecutive years upon arrival on the breeding grounds and assigned them via stable isotope analysis to their wintering areas. Analysis of the vegetation structure within blackcap territories revealed different microhabitat preferences of birds migrating to distinct wintering areas. Blackcaps arriving early on the breeding grounds had higher survival rates, better body condition and higher multilocus heterozygosities than later arriving birds. We did however not find an effect of parasite infection status on arrival time. Our results suggest that early arriving birds have disproportionate effects on population dynamics. Allochrony and habitat isolation may thus act together to facilitate ongoing divergence in hybrid zones, and migratory divides in particular.

the aquatic warbler Acrocephalus paludicola is the only globally threatened passerine breeding in Europe. We studied morphometric traits of 176 individuals captured at one of the key European autumn stopover sites, the Loire estuary on the Atlantic coast of France, in relation to age (first-year and older) and sex (based on molecular determination). We found significant sex differences in wing length, third primary feather length and body mass, with males being longerwinged and heavier than females; adult females also had deeper bills. however, high overlap in all measurements between the sexes meant the best discriminant functions based on wing length and bill depth (adults) and wing length (inmatures) correctly classified only 87% and 75% of individuals, respectively. the mean potential non-stop flight range of autumn staging birds at the Loire estuary with high fuel load was estimated at 1,178 km for adults and 926 km for immatures. We conclude that in autumn migrant aquatic warblers probably do not fly directly to wintering grounds in west Africa. Instead they gain significant body mass for onward migration at a few key stopover sites in western Europe and the southern mediterranean region. Conservation of a series of important refuelling stopover sites, especially wet grassland habitats, along the migration route is therefore essential for effective protection of the aquatic warbler.

For many migratory bird species, the latitudinal range of the winter distribution spans thousands of kilometres, thus encompassing considerable variation in individual migration distances. Pressure to winter near breeding areas is thought to be a strong driver of the evolution of migration patterns, as individuals undertaking a shorter migration are generally considered to benefit from earlier arrival on the breeding grounds. However, the influence of migration distance on timing of arrival is difficult to quantify because of the large scales over which individuals must be tracked. Using a unique dataset of individually-marked Icelandic black-tailed godwits Limosa limosa islandica tracked throughout the migratory range by a network of hundreds of volunteer observers, we quantify the consequences of migrating different distances for the use of stop-over sites and timing of arrival in Iceland. Modelling of potential flight distances and tracking of individuals from across the winter range shows that individuals wintering further from the breeding grounds must undertake a stop-over during spring migration. However, despite travelling twice the distance and undertaking a stop-over, individuals wintering furthest from the breeding grounds are able to overtake their conspecifics on spring migration and arrive earlier in Iceland. Wintering further from the breeding grounds can therefore be advantageous in migratory species, even when this requires the use of stop-over sites which lengthen the migratory journey. As early arrival on breeding sites confers advantages for breeding success, the capacity of longer distance migrants to overtake conspecifics is likely to influence the fitness consequences of individual migration strategies. Variation in the quality of wintering and stopover sites throughout the range can therefore outweigh the benefits of wintering close to the breeding grounds, and may be a primary driver of the evolution of specific migration routes and patterns.

Large numbers of waders migrating northward in spring use the Sivash, a large system of shallow, brackish and hypersaline lagoons in the Black Sea and Azov Sea region (Ukraine). The bottoms of these lagoons are often uncovered by the wind. Hence, for waders the time and space available for feeding depend on wind conditions. In hypersaline lagoons the benthic and pelagic fauna was very poor, consisting mainly of chironomid larvae (0.19 g AFDMom "2) and brine shrimps Artemia salina, respectively. Brine shrimp abundance was correlated with salinity, wind force, wind direction and water depth. Dunlin Calidris alpina and curlew sandpiper Calidris ferruginea were the only species feeding on brine shrimp. As brine shrimp densities are higher in deeper water, smaller waders such as broad-billed sandpipers Limicola falcinellus are too short-legged to reach exploitable densities of brine shrimp. In brackish lagoons the benthic and pelagic fauna was rich, consisting of polychaetes, bivalves, gastropods, chironomid larvae, isopods and amphipods (8.9 to 30.5 g AFDM-m'2), but there were no brine shrimps. Prey biomass increased with the distance from the coast, being highest on the site that was most frequently inundated. Dunlin, broad-billed sandpiper and grey plover Pluvialis squatarola were the most abundant birds in the brackish lagoon. Due to the effects of wind-tides only a small area was usually available as a feeding site. Gammarus insensibilis was the alternative prey resource in the water layer, and their density varied with wind direction in the same way as brine shrimp. Curlew sandpipers and dunlins in the hypersaline lagoons and broad-billed sandpipers in the brackish lagoons often changed feeding sites, probably following the variation in prey availability. Only because of the large size and variety of lagoons are waders in the Sivash always able to find good feeding sites.

The Greenlandic and west-central Siberian breeding populations of Sanderlings Calidris alba are separated by ca. 2000 km during the breeding season, but mix in Europe to some extent during migration. However, the number of Siberian Sanderlings that spend the nonbreeding season along the East Atlantic Flyway (extending from western Europe to South Africa), if any, is unknown. Although both populations are considered part of the nominate subspecies C. a. alba based on morphology, population structure in Sanderlings has yet to be described with molecular methods. We examined genetic differentiation at the mtDNA control region (CR) and seven microsatellite loci between Greenland- and Siberia-breeding Sanderlings in order to: (1) develop a diagnostic tool
for assessing the breeding origin of Sanderlings along the East Atlantic Flyway, and (2) provide a comparison with the co-distributed and ecologically similar Red Knot, in which CR differentiation of geographically analogous populations (C. canutus islandica and C. c. canutus) has indicated isolation of lineages near the time of the last glacial maximum. By contrast, we found only weak differentiation between the Sanderling breeding populations at the CR, and no differentiation at microsatellite loci. These results suggest that the assignment of breeding origin of Sanderlings on Afro-European flyways will not be possible with simple and inexpensive genetic methods, and imply that Sanderlings and Red Knots have very different
post-glacial phylogeographic histories.

Aim: Over the last two decades, thousands of northward migrating ruffs (Philomachus pugnax) have disappeared from western European staging sites. These migratory ruffs were partly temperate breeding birds, but most individuals head towards the Eurasian Arctic tundras where 95% of the global population breeds. This regional decline may represent either: (1) local loss of breeding birds in western Europe, (2) a global decline, (3) shift(s) in distribution or (4) a combination of these.

Location: Northern Eurasia.

Methods: To put the declines in western Europe in context, we analysed Arctic monitoring data from the last two decades (Soloviev & Tomkovich, 2009) to detect changes in regional breeding densities across northern Eurasia. We used a novel approach applying generalized additive modelling (GAM) and generalized estimations equations (GEE).

Results: We show that the global breeding population of ruffs has made a significant eastwards shift into the Asian part of the breeding range. In the European Arctic, ruffs decreased during the last 18 years. At the same time, in western Siberia, ruffs increased. In eastern Siberia, no significant population changes could be detected. These changes corroborate the finding that during northward migration, growing numbers of ruffs avoided staging areas in the Netherlands and Sweden and started migrating along a more easterly route leading into western Siberia.

Main conclusions: We detected an unprecedented large-scale population redistribution of ruffs and suggest that this is a response to loss of habitat quality at the traditional staging site in the Netherlands.

Contingent individual performance can depend on the environment experienced at previous life-stages. Migratory birds are especially susceptible to such carry-over effects as they periodically travel between breeding ranges and ‘wintering’ areas where they may experience broadly different ecological conditions. However, the study of carry-over effects is hampered by the difficulty of tracking vagile organisms throughout their annual life-cycle. Using information from light-level geolocators on the barn swallow (Hirundo rustica), we tested if feather growth bar width (GBW), a proxy of feather growth rate which depends on individual condition, and wing isometric size and shape predict the phenology of subsequent migration. GBW did not predict duration of wintering but negatively predicted the duration of spring migration and arrival date to the breeding sites, suggesting that migration phenology is not constrained by molt, and individuals in prime condition achieve both faster molt and earlier arrival. Wing morphology did not predict migration duration, as expected if wing shape were optimized for foraging, rather than migration performance, in this aerially foraging, insectivorous bird. Thus, we showed for the first time that migration phenology in a long-distance migratory bird covaries with body condition during wintering, as reflected by the growth rate of feathers.

Previous studies have shown that preen wax composition in some sandpipers shifts from the usual monoesters to diesters during the breeding season, possibly to reduce the ability of mammalian predators to find nests using olfactory cues. To investigate further the relationship between incubation and wax secretion, we examined seven sandpiper species with different incubation patterns (species in which both sexes incubate, in which only males incubate and in which only females incubate). During the breeding period, diester preen wax was secreted almost exclusively by the incubating sex in species with uniparental incubation, and by both sexes in species with biparental incubation. These findings suggest that diester preen waxes have a function that is directly related to incubation. Unexpectedly, in female-incubating Curlew Sandpiper Calidris ferruginea and Buff-breasted Sandpiper
Tryngites subruficollis , some males also secreted diester preen waxes during the breeding period. This suggests that some males may in fact incubate, that these waxes may be a remnant from their evolutionary past when both sexes incubated, or that males need to be olfactorally cryptic because they are involved in the making of nest scrapes.
The seasonal pattern of preen wax composition was also studied in captive male, female and female-mimicking male (‘faeder’) Ruff Philomachus pugnax. Captive female Ruff changed preen wax composition from monoesters to diesters in the spring despite the fact that no incubation took place. This suggests that circannual rhythms rather than actual incubation behaviour may trigger the shift to diester waxes. All captive male Ruff, including the faeders, continued to secrete monoesters, supporting the hypothesis that only the incubating sex secretes diesters.

A majority of Eurasian short-distance migrants moult after breeding and before autumn migration, while most long-distance migrants perform a winter moult in the tropics after autumn migration. Another strategy among long-distance migrants is a partial moult on the breeding grounds, suspended moult and then completion of moult on the wintering grounds. The Savi’s Warbler Locustella luscinioides is a small passerine adopting such a ‘suspended moulting’ strategy. Here, we investigate the sequence and extent of the post-breeding moult in Savi’s Warblers breeding in and migrating through northern Poland in relation to sex, body mass and date. We analysed 65 molecularly sexed adult Savi’s Warblers (32 females and 33 males) caught during autumn migration in 2010– 2011. Adult Savi’s Warblers from the studied populations were found to suspend moult. Exchange of wing feathers started at the third primary (P3) and progressed in both directions. The onset of secondary moult began with S1 and occurred when P6 was shed. Tail moult occurred almost simultaneously with the secondaries. We did not find any significant differences between the sexes in time and extent of moult. Lack of sex differences in the time of moulting suggests comparable post-breeding condition (fat load, body mass) of females and males. In contrast to the present study, adults caught in Western Europe started post-breeding moult from P5, which may be explained by different populations migrating through northern Poland and Western Europe.

It has recently been shown that sandpipers (Scolopacidae) abruptly switch the chemical composition of their preen gland secretions from mono- to diester waxes just before the
period of courtship. The timing and context of the shift suggested that diesters could provide a visible quality signal during mate choice. We used captive red knots Calidris
canutus to test whether mono- and diester preen waxes affect the light reflectance (‘‘colour’’) of the plumage. We also determined light absorbance spectra of the two wax types. The reflectance of breast feathers of the breeding plumage was measured with spectrophotometry when birds secreted monoesters and six weeks later when they secreted diester preen waxes. Light reflectance was also measured after removing the mono- and diester waxes from the plumage with a solvent. The results show that: (1) diester preen waxes absorb more light, especially ultraviolet (UV), than monoester
preen waxes, but that (2) the compositional shift in the preen waxes did not change plumage reflectance and, (3) the removal of preen waxes did not change the reflectance
of the plumage within the light spectrum assumed visible to birds (320
/700 nm). This is not consistent with the idea that compositional shifts in the preen waxes of red knots
have a visual function.

1. Animals adjust to seasonal challenges in physical, behavioural and spatial ways. Such adjustments are commonly associated with diet changes that often can be characterised isotopically. 2. We introduce the 'double diet switch model', with which the occurrence and timing of two subsequent diet switches of an individual animal can be traced with a single sample assayed for stable isotopes. We demonstrate the model for Sanderling, Calidris alba, a small shorebird that migrates from the Nearctic tundra breeding grounds to the intertidal flats of the Wadden Sea; during this migration some birds may stage in the North Atlantic areas. 3. The 'double diet switch model' successfully predicted the occurrence and timing of two diet switches in 59 San-derlings captured in the Wadden Sea in July–September. Excluding birds that likely had over-summered at North Atlantic staging areas, the model predicted that Sanderlings departed from the Arctic on 13 July (range: 9–17 July), had a staging duration of 18Á6 days in the North Atlantic, and arrived in the Wadden Sea on 1 August (31 July–1 August).The estimated mean Arctic departure dates coincided with the mean hatching date, suggesting that many individuals failed to produce young or left the care to a partner. Estimated mean arrival date matched the main arrival period in the Wadden Sea obtained from observation data. In this study we did not use lipid-free tissues, which may bias model predictions. After correcting for lipid components, the estimated departure date was 11 days later and the staging duration 8Á5 days shorter, while arrival date was similar. 4. The 'double diet switch model' successfully identified the occurrence and timing of two subsequent diet switches. The 'double diet switch model' will not only apply to switches between three isotopic levels (as in the case study on Sanderling) but also to scenarios where the second switch reverses to the initial isotopic level. Due to this general applicability, the model can be adapted to a wide range of taxa and situations. Foreseeable applications include changes in habitat and food type, ontogenetic development or drastic phenotypic changes such as the metamorphosis in insects and amphibians.

Despite the worldwide occurrence of Sanderlings Calidris alba on popular beaches, strikingly little is known about their biology compared to other common waders. Here we review the limited available knowledge of Sanderlings that use African–Eurasian flyways. The basis for this review was a workshop on Sanderlings, held during the International Wader Study Group conference in Jastrzębia Góra, Poland in 2008. We focus on biogeography, trends, numbers, diet, migration patterns and reproduction. Gaps in our knowledge are identified and we discuss the evidence for a Siberian origin of Sanderlings wintering in NW Europe, and plead for more
non-estuarine surveys and collaboration between colour-ring projects both in space and time to get a better understanding of population dynamics and migration phenology.

To be able to set priorities in species conservation planning, we need to know how these species prioritize the environment themselves, i.e. what they consider
to be better and worse sites. We present a unique and relevant case from tropical West-Africa based on 20 years of monthly counts of wetland sites spread along the 550 km long coast of Ghana. The Ghanaian Sanderling Calidris alba
population increased almost fourfold from average monthly total counts of c. 1350 Sanderlings to 4850 during the study period. Interestingly, with this considerable increase, the sites with the larger numbers at the start of the survey showed the smallest relative increases during 20 years of monitoring. This pattern is consistent with a buffer effect and suggests that with an increasing overall population the best quality sites are filled up, so that additional birds will be forced to use lower quality sites. The preferred site in Ghana, a stretch of beach near the village of Esiama between the Amansuri-Ankobra estuaries, is now entirely unprotected. We argue that the site should be placed higher on the conservation agenda given the fact that up to 3.5% of the Sanderling population connecting Greenland with West- and southern Africa rely on this site.

Nous avons comparé l'utilisation des réserves corporelles chez des individus reproducteurs de Branta leucopsis dans les colonies traditionnelles de l'Arctique dans la mer de Barents avec celle de colonies récemment établies de la zone tempérée de la mer Baltique et de la mer du Nord. Pour ce faire, nous avons étudié la perte de la masse corporelle des femelles et l'utilisation des réserves de graisses et de protéines au cours de l'incubation. La perte quotidienne de la masse corporelle était en moyenne presque identique dans les 2 populations des régions tempérées (17,0 g et 16,5 g dans la mer Baltique et la mer du Nord, respectivement), alors que les femelles se reproduisant dans l'Arctique ont perdu significativement moins de poids (10,6 g jour −1 ). Les femelles des régions tempérées ont débuté l'incubation avec une masse corporelle plus élevée de 125 g par rapport à celle des femelles de l'Arctique. Toutefois, à la fin de l'incubation, la masse corporelle était similaire entre les 3 populations, soit en moyenne de 1 458 g. La perte de masse corporelle durant l'incubation atteignait 23 % (mer du Nord), 22 % (mer Baltique) et 15 % (mer de Barents). La masse des graisses, telle que mesurée par une dilution isotopique dans un sous-échantillon de femelles, était constamment plus élevée chez les oiseaux de la mer du Nord que ceux de la mer de Barents. Néanmoins, les deux populations présentaient des taux de perte de la masse de graisses similaires (9,4 g jour −1 , en moyenne). En revanche, la perte de masse maigre (présumée représenter les protéines hydratées) s'élève à 9,3 g jour −1 chez les oiseaux de la mer du Nord, contre seulement 1,5 g jour −1 chez les oiseaux de la mer de Barents. Le contenu énergétique de 1 g de masse corporelle utilisée était de 21,1 kJ (mer du Nord) et 34,9 kJ (mer de Barents), ce qui équivaut à 376 kJ jour −1 et 415 kJ jour −1 retirées des réserves énergétiques, respectivement. Nous suggérons que les différences en termes d'assiduité au nid et des demandes post-incubation sont responsables de l'utilisation différentielle des réserves corporelles des individus de B. leucopsis des régions tempérées et arctiques.

Seasonal bird migration involves long flights, but most time is actually spent at intermediate staging areas. The duration of stay at these sites can be evaluated with mark–recapture methods that employ day-to-day local encounters of individually marked birds. Estimates of staging duration are based on two probabilities: the immigration probability, the complement of a bird’s seniority to an area, and the emigration probability, the complement of the staying probability. Estimating total staging duration from seniority and staying probabilities requires validation for resighting data and here we compare three data categories of Ruffs Philomachus pugnax passing through The Netherlands during northward migration: (1) newly colour-ringed, (2) previously colour-ringed and (3) radio-tagged Ruffs (recorded by automated receiving stations). Between 2004 and 2008, 4363 resighting histories and 95 telemetry recording histories were collected. As sample sizes for females were low, only data for males were analysed. Possible catching effects affecting estimates of staging duration were explored. Staying probability was estimated for all data. Seniority however, could not be estimated for newly marked Ruffs; the assumption of equal ‘capture’ probability for reverse-time models applied to estimate seniority is violated for seasonal resighting histories starting with a catching event. Therefore, estimates of total staging duration were based on resightings of previously colourmarked birds only. For radio-tagged birds a minimal staging duration (time between tagging and last recording) was calculated. Modelling indicated that newly colour-ringed birds had a higher staying probability than previously colour-ringed birds, but the difference translated to a prolonged staging duration in newly ringed birds of only 0.4–0.5 d, suggesting a very small catching effect. The minimal staging duration of radio-tagged birds validated estimates of staging duration for colour-ringed birds in 2007 but not in 2005. In 2005 a low resighting probability resulted in underestimates of staging duration. We conclude that (1) estimates of staying probability can be affected by catching although effects on staging duration might be small, and that (2) low resighting probabilities can lead to underestimates in staging duration. In our study previously ringed Ruffs resighted in 2006–08 yielded reliable estimates of staging duration as data had sufficiently high resighting probabilities. Average staging durations varied between 19 d in 2008 and 23 d in 2006.

Haemosporidian blood parasites are frequent amongst passerines. Though they often do not cause detectable
consequences to host health, however, their presence or absence and also their prevalence across host
populations may potentially carry meaningful information about the health, stress, body condition and viability
of bird individuals or populations. The study of migratory birds captured in Eilat, Israel, allowed us to evaluate
the prevalence of blood parasite infections in a wide range of both migrant and resident species in spring
(N = 1,950) and autumn (N = 538) of 2004 and 2005. According to blood film microscopy, Haemoproteus spp.
and Leucocytozoon spp. were more prevalent in the spring than in the autumn (0.289, 0.082 vs. 0.132, 0.033,
respectively), whilst Plasmodium spp. exhibited a slight opposite trend (0.034, 0.056). All other parasites (such
as trypanosomes, microfilaria and haemococcidians) were rare. During the spring seasons, prevalences were
significantly higher in migrant than in resident species, whilst this difference was only marginally significant in
the autumn. Given that Eilat is a migration hotspot for several Palearctic passerine species, the present descriptive
study may hopefully serve to set the baseline values for future long-term epidemiological monitoring.

In spring, the Ruff Philomachus pugnax passes through European inland sites in large numbers. Birds from eastern and western parts of the breeding range may differ in biometrics, but data on this species in eastern Europe are scarce. The aim of this study was to describe the biometrics of Ruffs migrating through southern Belarus in spring. In 2004, 242 birds were sexed by DNA analysis. Three birds sexed as males had female plumage but wing lengths intermediate between females and breeding-plumage males, and were identified as cryptic males or ‘faeders’. Between 2001 and 2005, 2,237 Ruffs were ringed at the study site (1,310 males in breeding plumage, 911 females and 14 faeders). There was a strong seasonal variation in sex ratio. For adult Ruffs wing length was the best predictor of sex. Total head length and tarsusplus-toe length distributions overlapped slightly between the sexes. There was evidence for slight bimodality in the distributions of wing, bill and tarsus-plus-toe length in non-faeder males and in wing and bill length distributions for females. Mean wing lengths of Ruffs passing through the Belarus study site were similar to those birds from other locations in Europe and North Africa, but different from birds from South Africa, Yamal and the middle Lena River, suggesting that Ruffs have at least two different breeding populations.

In May 1990, more than 4500 km away from, and up to three weeks before arriving on their high Arctic breeding grounds, individuals of two subspecies of Knots, Calidris canutus islandica and canutus, showed ground display and song whilst foraging in flocks on the tidal flats in the Wadden Sea of Schleswig-Holstein, FRG. Similar displays and songs were recorded in May 1987 and 1988 on the staging areas of C.c. islandica in northwest Iceland. The display behaviour, identified as the 'tail-up display', is probably performed only by males towards females, and occurs commonly just after arrival at the tundra breeding sites. Tail-up displays may result in copulations both on the staging and on the breeding sites. On the staging sites, tail-up displays were most frequent in the days prior to the departure of flocks to a subsequent stopover area (Iceland) or for presumed direct flights to the Canadian and the Siberian Arctic. Our observations suggest that the behavioural condition required for reproduction may, at least in males, develop some weeks before the actual arrival in the breeding areas.

Capsule: Fæders (males that are female look-alikes) associate with males rather than females, at several different spatial scales.

Aims: To test the prediction that the occurrence in space and time of fæders on ecological grounds should track that of females.

Methods: The fraction of fæders was estimated in five morphometric data sets that were collected over four decades in four different countries in three different seasons (comprising 9133 Ruffs). The regression of fæder–female fractions was tested against the null model assuming that the number of fæders is 1.0% of females.

Results: The fraction of fæders in catches averaged 1.03%, varying between 0.3% in autumn in the UK up to 0.85% in Sénégal in winter and 1.04% in The Netherlands in spring. On a stopover in The Netherlands the fraction decreased from 1.3% to 0.7% when the females started to arrive. At all four spatial and temporal scales the regression of fæder–female fractions deviated from the null model: we found high fractions of fæders in catches with low fractions of females, indicating that fæders rather associate with the larger-sized ´normal´ males.

Conclusion: We suggest that fæders spend the winter, and migrate with, the larger-sized lekking males, and we propose that any survival costs associated with the use of suboptimal habitats is compensated by higher reproductive success as sneakers on leks.

During May 1992 the spring migration of the Broad-billed Sandpiper in the Sivash, Ukraine, was studied. The numbers increased rapidly from some tens early May up to an estimated 6,000 in the last ten days of May. The birds preferred mudflats in the eastern part of the area which proved to be rich in benthic fauna. In the central Sivash, lower numbers were found and only pelagic prey was available. The Sivash can be considered as one of the most important stop-over sites for the Broad-billed Sandpiper during spring migration, for at least 30% of the European population was found to be present.

Ruffs are migrant shorebirds of inland habitats. This thesis describes seasonal migration and changes in range occupation of ruffs, and presents a comparative analysis of the population genetics of ruffs and related shorebird species. Two hypotheses about shorebird evolution are addressed. Firstly, it is questioned whether instead of evolutionary constraints on migration routes (inflexible migration hypothesis), flexible routing might better explain observations on migration in shorebirds. Secondly, we test whether genetic variation in ruff and other inland, freshwater shorebirds is higher than in marine, coastal shorebirds (habitat dichotomy hypothesis).

The present report puts forth a systematic checklist of bird species observed at Amboli Ghat in Maharashtra from 2009 to 2012, along with information on their status. A total of 208 species were recorded, which is around 15% of bird species of the Indian subcontinent. A family-wise analysis showed that the families Accipitridae and Muscicapidae (14 species each) followed by Ardeidae dominated the avifauna of the region. The study also revealed that the area consisted of 11 species of birds that are classified under Near Threatened category and two under Vulnerable category of IUCN. This study highlights the urgent need to conserve the biodiversity-rich area of Amboli Ghat with long-term plans.

In spring, large numbers of migrating Broad-billed Sandpipers make a stop-over in the Sivash, a shallow lagoon system in the Crimea, Ukraine, between the Black Sea and the Sea of Azov. Observed fuelling rates are high and, in just a few weeks, the birds can build up sufficient departure mass to reach their breeding grounds in a single non-stop flight (Verkuil et al. 2006). For feeding, Broad-billed Sandpipers prefer the brackish lagoons with a diverse benthic prey community. They ignore the hypersaline lagoons which are teeming with brine shrimp (Artemia sp.), a common prey for migrating Dunlins and Curlew Sandpipers in this area (Verkuil et al. 2003). In this paper we report on diet choice in relation to gut processing efficiency of different possible prey species for Broad-billed Sandpipers. We ask two questions: “Why do Broad-billed Sandpipers avoid feeding on brine shrimp in the hypersaline lagoons?” and “Do they specialize on one particular prey species in the brackish lagoons?”. Digestion efficiency of birds fed with brine shrimp was lower than for birds fed with the polychaete Nereis diversicolor or the crustacean Gammarus insensibilis. In the brackish lagoons, prey items seen ingested were both polychaetes (Nereis diversicolor) and larger crustaceans. Field observations on defecation intervals compared with identical observations on captive individuals suggest that both polychaetes and crustaceans were included in the diet. Although studies from other staging and wintering sites report that Broad-billed Sandpiper usually eat polychaetes, we suggest that they optimize their energy intake by eating a multi-course meal.