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In response to environmental change, species have been observed altering their migratory behaviours. Few studies, however, have been able to determine whether these alterations resulted from inherited, plastic or flexible changes. Here, we present a unique observation of a rapid population-level shift in migratory routes—over 300 km from Spain to Portugal—by continental black-tailed godwits Limosa limosa limosa. This shift did not result from adult godwits changing staging sites, as adult site use was highly consistent. Rather, the shift resulted from young godwits predominantly using Portugal over Spain. We found no differences in reproductive success or survival among individuals using either staging site, indicating that the shift resulted from developmental plasticity rather than natural selection. Our results therefore suggest that new migratory routes can develop within a generation and that young individuals may be the agents of such rapid changes.

Aim: Molluscivorous shorebirds supposedly developed their present wintering distribution after the last ice age. Currently, molluscivorous shorebirds are abundant on almost all shores of the world, except for those in the Indo-West Pacific (IWP). Long before shorebirds arrived on the scene, molluscan prey in the IWP evolved strong anti-predation traits in a prolonged evolutionary arms race with durophagous predators including brachyuran crabs. Here, we investigate whether the absence of molluscivorous shorebirds from a site in Oman can be explained by the molluscan community being too well-defended.Location: The intertidal mudflats of Barr Al Hikman, Oman.Methods: Based on samples from 282 locations across the intertidal area the standing stock of the macrozoobenthic community was investigated. By measuring anti-predation traits (burrowing depth, size and strength of armour), the fraction of molluscs available to molluscivorous shorebirds was calculated.Results: Molluscs dominated the macrozoobenthic community at Barr Al Hikman. However, less than 17% of the total molluscan biomass was available to shorebirds. Most molluscs were unavailable either because of their hard-to-crush shells, or because they lived too deeply in the sediment. Repair scars and direct observations confirmed crab predation on molluscs. Although standing stock densities of the Barr Al Hikman molluscs were of the same order of magnitude as at intertidal mudflat areas where molluscivorous shorebirds are abundant, the molluscan biomass available to shorebirds was distinctly lower at Barr Al Hikman.Main conclusions: The established strong molluscan anti-predation traits against crabs precludes molluscan exploitation by shorebirds at Barr Al Hikman. This study exemplifies that dispersal of “novel” predators is hampered in areas where native predators and prey exhibit strongly developed attack and defence mechanisms, and highlights that evolutionary arms races can have consequences for the global dis

Rock Sandpipers Calidris ptilocnemis have the most northerly non-breeding distribution of any shorebird in the Pacific Basin (upper Cook Inlet, Alaska; 61°N, 151°W). In terms of freezing temperatures, persistent winds and pervasive ice, this site is the harshest used by shorebirds during winter. We integrated physiological, metabolic, behavioural and environmental aspects of the non-breeding ecology of Rock Sandpipers at the northern extent of their range to determine the relative importance of these factors in facilitating their unique non-breeding ecology. Not surprisingly, estimated daily energetic demands were greatest during January, the coldest period of winter. These estimates were greatest for foraging birds, and exceeded basal metabolic rates by a factor of 6.5, a scope of increase that approaches the maximum sustained rate of energetic output by shorebirds during periods of migration, but far exceeds these periods in duration. We assessed the quality of their primary prey, the bivalve Macoma balthica, to determine the daily foraging duration required by Rock Sandpipers to satisfy such energetic demands. Based on size-specific estimates of M. balthica quality, Rock Sandpipers require over 13 h/day of foraging time in upper Cook Inlet in January, even when feeding on the highest quality prey. This range approaches the average daily duration of mudflat availability in this region (c. 18 h), a maximum value that annually decreases due to the accumulation of shore-fast ice. Rock Sandpipers are likely to maximize access to foraging sites by following the exposure of ice-free mudflats across the upper Cook Inlet region and by selecting smaller, higher quality M. balthica to minimize foraging times. Ultimately, this unusual non-breeding ecology relies on the high quality of their prey resources. Compared with other sites across their range, M. balthica from upper Cook Inlet have relatively light shells, potentially the result of the region's depauperate invertebra

Capsule: Most Continental Black-tailed Godwits Limosa limosa limosa using the Doñana wetlandsduring post-breeding migration appear to begin moult before they arrive and suspend moultbefore they migrate onwards to West Africa.Aims: We aim to describe the primary moult strategies and patterns in the Continental Black-tailedGodwits using the Doñana wetlands, a major passage and wintering area for waterbirds in southernSpain.Methods: Individual godwits were captured, marked and their primary moult was scored in Doñanaduring the non-breeding season (June–March) in 2011 and 2012. Data from resightings of colourmarkedgodwits and birds equipped with satellite transmitters were used to estimate stopoverduration during post-breeding migration (June–September) to determine if godwits move toWest Africa before completing their primary moult.Results: Average primary moult duration was estimated to be 84 days ± 9 se, during 29 June–21September and did not differ between sexes. Only 2% of individuals were observed withsuspended moult. We estimated stopover duration in Doñana to be 13 days ± 2 se beforemigrating to West Africa.Conclusions: Most godwits stage for about two weeks in the Doñana wetlands during southwardmigration, moult their primaries and appear to suspend moult before crossing the Sahara. Othersmay complete their primary moult in Doñana, or elsewhere in Europe and overwinter in Doñanawhere increasing numbers of godwits have been detected in recent years. A few individu

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Coastal food webs can be supported by local benthic or pelagic primary producers and by the import of organic matter. Distinguishing between these energy sources is essential for our understanding of ecosystem functioning. However, the relative contribution of these components to the food web at the landscape scale is often unclear, as many studies lack good taxonomic and spatial resolution across large areas. Here, using stable carbon isotopes, we report on the primary carbon sources for consumers and their spatial variability across one of the world's largest intertidal ecosystems (Dutch Wadden Sea; 1460 km2 intertidal surface area), at an exceptionally high taxonomic (178 species) and spatial resolution (9,165 samples from 839 locations). The absence of overlap in δ13C values between consumers and terrestrial organic matter suggests that benthic and pelagic producers dominate carbon input into this food web. In combination with the consistent enrichment of benthic primary producers (δ13C −16.3‰) relative to pelagic primary producers (δ13C −18.8) across the landscape, this allowed the use of a two-food-source isotope-mixing model. This spatially resolved modelling revealed that benthic primary producers (microphytobenthos) are the most important energy source for the majority of consumers at higher trophic levels (worms, molluscs, crustaceans, fish, and birds), and thus to the whole food web. In addition, we found large spatial heterogeneity in the δ13C values of benthic primary producers (δ13C −19.2 to −11.5‰) and primary consumers (δ13C −25.5 to −9.9‰), emphasizing the need for spatially explicit sampling of benthic and pelagic primary producers in coastal ecosystems. Our findings have important implications for our understanding of the functioning of ecological networks and for the management of coastal ecosystems.

Earthworms (Lumbricidae) are important prey for many birds. Based on theirown feeding ecology, earthworms can be separated into two ecotypes: the detritivoresthat feed on organic material and the geophages that feed on soil particlesand organic matter. Detritivores collect their food on the surface during thenight when they are exposed to nocturnal predators. Hungry animals tend toshow more risk-prone behaviour and may therefore be more vulnerable to birdpredation, so we expect well-fed detritivorous earthworms to visit the surfaceless frequently. In this study, we tested this hypothesis in dairy farmland in theprovince of Fryslân, The Netherlands. Two uniform grasslands were split, witheach half receiving either an early (1 February 2014) or a late (14 March 2014)farmyard manure application. Every two weeks, nocturnal surface activity ofearthworms was measured by counting surfacing earthworms from a slowlypushed cart. Furthermore, soil samples were taken for total abundances and tomeasure individual body conditions of earthworms. As predicted, the density ofsurfacing earthworms was on average 2.5 times higher in the fields before farmyardmanure was applied. Immature detritivores had significantly lower bodymasses in fields not yet manured, suggesting that these growing earthwormswere hungry. Differences in surfacing behaviour and body mass disappearedafter all fields had been given farmyard manure. We conclude that hunger forcesdetritivorous earthworms to the surface. After manure application, they appearsatisfied and avoid the risk of depredation by birds by staying away from the soilsurface. To promote earthworm availability for meadow birds, spreading farmyardmanure on the surface should occur as late in spring as possible. In thisway, hungry earthworms are forced to the surface and are available as meadowbird prey for longer periods.

Marine organisms adapt to complex temporal environments that includedaily, tidal, semi-lunar, lunar and seasonal cycles. However, our understandingof marine biological rhythms and their underlying molecularbasis is mainly confined to a few model organisms in rather simplistic laboratorysettings. Here, we use new empirical data and recent examples ofmarine biorhythms to highlight how field ecologists and laboratory chronobiologistscan complement each other’s efforts. First, with continuoustracking of intertidal shorebirds in the field, we reveal individual differencesin tidal and circadian foraging rhythms. Second, we demonstrate that shorebirdspecies that spend 8–10 months in tidal environments rarely maintainsuch tidal or circadian rhythms during breeding, likely because of other,more pertinent, temporally structured, local ecological pressures such as predationor social environment. Finally, we use examples of initial findingsfrom invertebrates (arthropods and polychaete worms) that are being developedas model species to study the molecular bases of lunar-relatedrhythms. These examples indicate that canonical circadian clock genes (i.e.the homologous clock genes identified in many higher organisms) maynot be involved in lunar/tidal phenotypes. Together, our results and theexamples we describe emphasize that linking field and laboratory studiesis likely to generate a better ecological appreciation of lunar-related rhythmsin the wild.This article ispart of the themed issue ‘Wild clocks: integrating chronobiologyand ecology to understand timekeeping in free-living animals’.

Prompted by the realization that parts of the coast of southern Jiangsu Province, China, are under threat of reclamation, we here summarize evidence that loss of intertidal habitats around the Yellow Sea and at other parts along the Chinese and Korean coasts has already led to severe population declines of migratory shorebirds, including multiple endangered species. All the evidence currently at hand suggest that the plans to reclaim (develop) additional intertidal habitat in this region poses a substantial threat to the remaining shorebird populations. We recommend that new Environmental Impact Assessments are warranted before further reductions in the extent of mudflats take place.

At a time when there is a growing discussion about the natural state of estuaries, a comparison of macrozoobenthoscommunities from two surveys conducted 30 years apart in the Ems Dollard estuary, in the easternWadden Sea, The Netherlands, provides a unique opportunity to compare changes over time. As expected, ourcomparison revealed a gradient in species composition from land (the Dollard) to sea (the Outer Ems) at bothpoints in time, with brackish species in the Dollard and more marine species in the Outer Ems (Wadden Sea).Total richness increased over time; however, this mainly reflected the immigration of new species and samplingdifferences. In the Dollard, total biomass declined over time, most likely reflecting de-eutrophication in this area.Strikingly, at the meeting point between the sea and the brackish Dollard, i.e. the Inner Ems, the communitycomposition changed from one dominated by bivalves (1970s) to one dominated by worms (since 2009). Thischange involved a reduction in total biomass, mainly of Mya arenaria, and immigration of polychaete worms(Marenzellaria viridis and Alitta succinea). In the Outer Ems, an increase in total biomass was observed, associatedwith the recent successful recruitment of Cerastoderma edule. This comparison highlights that historical dataprovides useful insights at large spatial scales. However, a full understanding of the complex dynamics of estuariesrequires an analysis of continuous long-term monitoring series.

Salinization is having a major impact on wetlands and its biota worldwide. Specifically, many migratoryanimals that rely on wetlands are increasingly exposed to elevated salinity on their nonbreedinggrounds. Experimental evidence suggests that physiological challenges associated with increasingsalinity may disrupt self-maintenance processes in these species. Nonetheless, the potential role ofsalinity as a driver of ecological carry-over effects remains unstudied. Here, we investigated the extentto which the use of saline wetlands during winter – inferred from feather stable isotope values – inducesresidual effects that carry over and influence physiological traits relevant to fitness in black-tailedgodwits Limosa limosa limosa on their northward migration. Overwintering males and females weresegregated 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 immuneresponsiveness to phytohaemagglutinin and sized-corrected body mass in godwits staging in southernEurope 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-overeffects and can help predict how migratory species should respond to future climate-induced increasesin salinity.

Ruff Philomachus pugnax staging in the Netherlands forage in agricultural grasslands,where they mainly eat earthworms (Lumbricidae). Food intake and the surface availabilityof earthworms were studied in dairy farmland of southwest Friesland in March–April2011. Daily changes in earthworm availability were quantified by counting visible earthworms.No earthworms were seen on the surface during daytime, but their numberssharply increased after sunset and remained high during the night. Nevertheless, intakerates of individual Ruff in different grasslands measured during daytime showed the typicalHolling type II functional response relationship with the surfacing earthworm densitiesmeasured at night. Radiotagging of Ruff in spring 2007 revealed that most, if not all,feeding occurs during the day, with the Ruff assembling at shoreline roosts at night. Thisraises the question of why Ruff do not feed at night, if prey can be caught more easilythan during daytime. In March–May 2013 we experimentally examined the visual andauditory sensory modalities used by Ruff to find and capture earthworms. Five maleswere kept in an indoor aviary and we recorded them individually foraging on trays with10 earthworms mixed with soil under various standardized light and white noise conditions.The number of earthworms discovered and eaten by Ruff increased with lightlevel, but only when white noise was played, suggesting that although they can detectearthworms by sight, Ruff also use auditory cues. We suggest that although surfacingnumbers of earthworms are highest during the night, diurnal intake rates are probablysufficient to avoid nocturnal foraging on a resource that is more available but perhapsless detectable at that time.

From 1950, spring temperatures in The Netherlands increased. Previousresearch suggested that advances in first egg dates of Lapwings Vanellusvanellus best correlate with climatic factors rather than with changes in farmingpractices. In an area constantly and uniformly managed especially for breedingmeadow birds (the reserve Giethoorn-Wanneperveen), nesting phenology ofLapwings was monitored over almost three decades (1988–2014). During thisperiod local average air temperatures across early spring (1 February – 31March) showed no change. Although first laying dates of the initial clutches(varying between 7 and 30 March) did not change either, the median laying dateof the first egg of all the clutches (varying between 21 March and 8 April)advanced by ten days (from 4 April to 25 March). Interestingly, laying dates wereassociated with temperatures, in that egg laying usually followed an increase intemperature in the previous weeks. As a consequence, whereas first layingdates of initial clutches correlated with temperatures in the 21 February – 31March interval, they did not with temperatures in the previous 1–20 Februaryinterval. Likewise, median laying dates of the first egg of all the clutches did notcorrelate with the temperatures in February and early March, but the two variableswere strongly correlated in the overlapping 11 March – 10 April interval.We found no associations with precipitation. That median laying dates (but notfirst laying dates) advanced without changes in the overall average springtemperature nor in habitat management, can only partly be explained by thefinding that hatching success steadily increased during the study (note that themore frequent replacement clutches would have delayed the measured medianlaying date in the earlier years). As hatching success of earlier clutches is higherthan that of later clutches, there may now be selection for earlier laying.

1. Migration is a widespread phenomenon in the animal kingdom. On the basis of theconsiderable variation that exists between and within species, and even withinpopulations, we may be able to infer the (age- and sex-specific) ecological trade-offsand constraints moulding migration systems from assessments of fitness associatedwith migration and wintering in different areas.2. During three consecutive breeding seasons, we compared the reproductive performance(timing of breeding, breeding success, chick body condition and post-fledgingsurvival) of Eurasian spoonbills Platalea leucorodia that breed at a single breedingsite in The Netherlands, but migrate different distances (c. 4,500 vs. 2,000 km,eitheror not crossing the Sahara) to and from wintering areas in southern Europeand West Africa. Using mark–recapture analysis, we further investigated whethersurvival until adulthood (recruitment probability) of chicks hatched between 2006and 2010 was related to their hatch date and body condition.3. Long-distance migrants bred later, particularly the males, and raised chicks ofpoorer body condition than short-distance migrants. Hatch dates strongly advancedwith increasing age in short-distance migrants, but hardly advanced in longdistancemigrants, causing the difference in timing of breeding between long- andshort-distance migrants to be more pronounced among older birds.4. Breeding success and chick body condition decreased over the season, and chicksthat fledged late in the season or in poor condition were less likely to survive untiladulthood. As a result, long-distance migrants—particularly the males and olderbirds—likely recruit fewer offspring into the breeding population than short-distancemigrants. This inference is important for predicting the population-level consequencesof changes in winter habitat suitability throughout the wintering range.5. Assuming that the long-distance migrants—being the birds that occupy the traditionalwintering areas—are not the poorer qual

Determining the sex of individuals through molecular methods is an increasinglyimportant research tool, particularly for studies of sexually monomorphic species.However, currently available primer sets to molecularly sex birds are known tocause difficulties in sexing Red Knots Calidris canutus and several other waders,due to amplification failure of, and polymorphisms on, the CHD-Z gene. Tocounter these problems, we developed a new primer set, 2602F/2669R, andshow that these primers can be used to reliably sex Red Knots and eight otherwader species in four genera. We expect these primers to be useful in a widerange of wader and possibly non-wader species.

Most processes within organisms, and most interactions between organismsand their environment, have distinct time profiles. The temporal coordinationof such processes is crucial across levels of biological organization, but disciplinesdiffer widely in their approaches to study timing. Such differences areaccentuated between ecologists, who are centrally concerned with a holisticview of an organism in relation to its external environment, and chronobiologists,who emphasize internal timekeeping within an organism and themechanisms of its adjustment to the environment. We argue that ecologicaland chronobiological perspectives are complementary, and that studies atthe intersection will enable both fields to jointly overcome obstacles that currentlyhinder progress. However, to achieve this integration, we first have tocross some conceptual barriers, clarifying prohibitively inaccessible terminologies.We critically assess main assumptions and concepts in either field, aswell as their common interests. Both approaches intersect in their need tounderstand the extent and regulation of temporal plasticity, and in the conceptof ‘chronotype’, i.e. the characteristic temporal properties of individuals whichare the targets of natural and sexual selection. We then highlight promisingdevelopments, point out open questions, acknowledge difficulties and proposedirections for further integration of ecological and chronobiologicalperspectives through Wild Clock research.This article is part of the themed issue ‘Wild Clocks: integrating chronobiologyand ecology to understand timekeeping in free-living animals’.

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 Sanderlings 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 18·6 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 8·5 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

1. Animals frequently exhibit consistent among-individual differences in behavioural and physiologicaltraits that are inherently flexible. Why should individuals differ consistently in theirexpression of labile traits? Recently, positive feedbacks between state and behaviour have beenproposed as a possible explanation for the maintenance of consistent among-individual differencesin both state and behaviour. If state affects behaviour, and behaviour reciprocally affectsstate, then differences in either state or behaviour that arise among individuals even by chancecould be maintained over extended periods of time.2. We tested for positive feedbacks experimentally using wild-caught red knots (Calidris canutusislandica). In the wild, knots exhibit consistent among-individual differences in digestivephysiology (the mass of the muscular part of the stomach, the gizzard) and foraging behaviour(diet), two inherently labile traits.3. Experimentally manipulated diet quality had a large effect on gizzard mass. Experimentallymanipulated gizzard mass reciprocally influenced total food eaten during ad libitum trials.4. The effect of gizzard mass on diet choice, though in the predicted direction, was not statisticallysignificant. Individuals exhibited consistent differences in foraging behaviour of unknownorigin independent of current gizzard mass, as well as large residual unexplained variance inforaging behaviour. These two sources of variation in foraging behaviour overruled the gizzardmass-dependent foraging behaviour and hence eroded the treatment-related differences in gizzardmass.5. We conclude that positive feedbacks between diet choice and gizzard mass play at best alimited role in maintaining among-individual variation in gizzard mass in red knots. Furthermore,we suggest that many models of state–behaviour feedbacks likely overestimate theirpotential importance in maintaining long-term among-individual variation in labile traitsbecause most models of state–behaviour feed

Costsof migration, in terms of time, energy, and mortality risk, have a strong theoretical and empirical foundation in thestudy of birds. We expect these costs to be most severe for extreme long-distance migratory landbirds, whose demandingannual routines (e.g. non-stop flights  8000 km and return journeys  30 000 km) may approach their maximumphysiological capabilities. To explore whether this is true, we review evidence in long-jump migratory shorebirds(Scolopacidae), focusing most on the prototypical example, the Alaska-breeding bar-tailed godwit Limosa lapponicabaueri. Contrary to expectations, these and similar birds demonstrate high adult survival, little evidence for elevatedmortality during migration, no apparent minimisation of non-stop flight distances, and low inter- and intra-individualvariation in migration performance. Two key aspects of extreme migrants may explain these findings: 1) a counterintuitivelyconservative annual-cycle strategy, which minimises risks and enables dissipation of carry-over effects beforefitness consequences arise; and 2) selection pressure during early life, which quickly removes low-performing individualsfrom the population. We hypothesise that these two factors, applicable to extreme strategies in a wide range of taxa, act totruncate the range of individual quality in a population, and decrease the prevalence and detectability of carry-over effects.Testing these hypotheses is challenging, as it requires comparative studies of demography and individual quality spectraalong a continuum of extremeness. However, it has important potential implications for interpreting individual variation,designing studies of cross-seasonal interactions or costs of migration, and recognising early-warning signs of populationdecline. For example, the most extreme shorebird migrations rely on abundant but difficult-to-access resources; the highminimum individual performance required for survival predicts that degradation of these resource hot-sp

Coastal wetlands are heterogeneous systems with multiple inputs and complex interactionswithin local food webs. Interpreting such complexity is limited by incomplete knowledgeof trophic interactions among organisms. Although widely recognized as secondary consumersand predators of intertidal macroinvertebrates, shorebirds can also consume lower-trophic-levelfood sources, and frequently forage in adjacent supratidal habitats. To ascertain potential trophiclinks between overwintering shorebirds and alternative non-standard food sources, we collectedcarbon and nitrogen stable isotope data of shorebirds and benthic organisms from 4 coastal wetlandsalong the Eastern Atlantic: Tejo Estuary, Portugal; Sidi-Moussa, Morocco; Banc d’Arguin,Mauritania; and Bijagós Archipelago, Guinea-Bissau. Using dual-isotope Bayesian mixing models,we evaluated the relative importance of intertidal benthic macroinvertebrates and 3 otherpotential food sources (biofilm and seagrass rhizomes from intertidal areas, and saltpan macroinvertebrates)in the diet of wintering shorebirds. Although intertidal macroinvertebrates form themain part of most shorebird species’ diet, our data revealed that supratidal saltpans can contributeto >30% of the biomass ingested by several shorebird species. Seagrass rhizomes represented>10% of the diet of several species in Banc d’Arguin and in Sidi Moussa. Little stint Calidris minutaappears to consume biofilm on all 3 wetlands where they were sampled, which is the first timebiofilm consumption by shorebirds has been detected along the East Atlantic Flyway. Empiricalevidence for generalized consumption of alternative food sources by intertidal avian predatorsshow the greater complexity and food web connectivity in and of intertidal habitats, and also withthe surrounding habitats.

Aim Habitat use and migration strategies of animals are often associated withspatial variation in parasite pressure, but how they relate to one another is notwell understood. Here, we use a large dataset on helminth species richness ofCharadriiform birds to test whether higher habitat diversity and seasonalmigration increase parasite richness in avian hosts.Location Global.Methods We compiled a global dataset on helminth species richness, habitatuse strategies (marine/freshwater/mixed wintering and osmotic generalist/specialist)and various ecological/life-history traits (migration distance, geographicalrange size, diet, body mass, sampling latitude) of Charadriiform birds. Totest if hosts with different habitat use strategies encounter different parasitepressures, we used comparative methods that correct for shared ancestry andphylogenetic uncertainty.Results Habitat generalists (mixed wintering habitats and osmotic generalists)harboured more parasite species than habitat specialists; marine- and freshwater-restricted hosts had similar helminth species richness. Contrary to previousresults, we found no association between parasite species richness and migrationdistance. Overall helminth species richness also increased with diet diversity,with no effects of other ecological/life-history traits.Main conclusions We suggest that birds exploiting diverse habitats and dietsare exposed to a more diverse parasite fauna and conclude that distributionpatterns and habitat use, rather than migration distance, shape parasite diversitywithin host populations. Overall, these results demonstrate the significantrole of habitat use in explaining how migration may indirectly affect parasiterichness in host populations.

Migrating long distances requires time and energy, and may interact with an individual’sperformance during breeding. These seasonal interactions in migratoryanimals are best described in populations with disjunct nonbreeding distributions.The black-tailedgodwit (Limosa limosa limosa), which breeds in agricultural grasslandsin Western Europe, has such a disjunct nonbreeding distribution: The majorityspend the nonbreeding season in West Africa, while a growing numberwinters north of the Sahara on the Iberian Peninsula. To test whether crossing theSahara has an effect on breeding season phenology and reproductive parameters,we examined differences in the timing of arrival, breeding habitat quality, laydate, egg volume, and daily nest survival among godwits (154 females and 157males), individually marked in a breeding area in the Netherlands for which winteringdestination was known on the basis of resightings. We also examinedwhether individual repeatability in arrival date differed between birds winteringnorth or south of the Sahara. Contrary to expectation, godwits wintering south ofthe Sahara arrived two days earlier and initiated their clutch six days earlier thangodwits wintering north of the Sahara. Arrival date was equally repeatable forboth groups, and egg volume larger in birds wintering north of the Sahara. Despitethese differences, we found no association between wintering location and thequality of breeding habitat or nest survival. This suggests that the crossing of animportant ecological barrier and doubling of the migration distance, twice a year,do not have clear negative reproductive consequences for some long-distancemigrants.

Although age-related spatial segregation is ubiquitous, the underlying mechanisms are poorly understood. Here, we aim to elucidatethe processes behind a previously established age-related foraging distribution of red knots (Calidris canutus canutus) in their mainwintering area in West Africa (Banc d’Arguin, Mauritania). Based on 10 years of observations of 1232 uniquely color-ringed individualsof 1 to 18+ years old, we examined whether the observed age-related foraging distribution resulted from 1) spatial differences in mortalityor 2) age-related shifts in habitat use. Using multistate capture–recapture modeling, we showed that with age foraging red knotsmoved away from the shoreline, that is, to areas with fewer surprise attacks by raptors. Considering uncertainties in the subjectivegradient in predation danger with increasing distance from shore (as assessed from correlations between vigilance and distance fromshore in foraging birds), we applied 2 different danger zone boundaries, at 40 m and 500 m from shore. Between years, red knots hada much higher chance to move from the dangerous nearshore area to the “safe” area beyond (71–78% and 26% for 40-m and 500-mdanger zone boundary, respectively), than vice versa (4% and 14%). For neither danger zone boundary value did we find differencesin annual mortality for individuals using either dangerous or safe zone, so the move away from the shore with age is attributed to individualcareers rather than differential mortality. We argue that longitudinal studies like ours will reveal that ontogenetic shifts in habitatuse are more common than so far acknowledged.

The Numeniini is a tribe of 13 wader species (Scolopacidae, Charadriiformes) of which seven are Near Threatened or globally threatened, including two Critically Endangered. To help inform conservation management and policy responses, we present the results of an expert assessment of the threats that members of this taxonomic group face across migratory flyways. Most threats are increasing in intensity, particularly in non-breeding areas, where habitat loss resulting from residential and commercial development, aquaculture, mining, transport, disturbance, problematic invasive species, pollution and climate change were regarded as having the greatest detrimental impact. Fewer threats (mining, disturbance, problematic native species and climate change) were identified as widely affecting breeding areas. Numeniini populations face the greatest number of non-breeding threats in the East Asian-Australasian Flyway, especially those associated with coastal reclamation; related threats were also identified across the Central and Atlantic Americas, and East Atlantic flyways. Threats on the breeding grounds were greatest in Central and Atlantic Americas, East Atlantic and West Asian flyways. Three priority actions were associated with monitoring and research: to monitor breeding population trends (which for species breeding in remote areas may best be achieved through surveys at key non-breeding sites), to deploy tracking technologies to identify migratory connectivity, and to monitor land-cover change across breeding and non-breeding areas. Two priority actions were focused on conservation and policy responses: to identify and effectively protect key non-breeding sites across all flyways (particularly in the East Asian- Australasian Flyway), and to implement successful conservation interventions at a sufficient scale across human-dominated landscapes for species’ recovery to be achieved. If implemented urgently, these measures in combination have the potential to alter the cu

1. Solar geolocators are relatively cheap and simple tools which are widely used to study the migration of animals,especially birds. The methods to estimate the geographic positions from the light-intensity patterns collectedby these loggers, however, are still under development.2. The accurate reconstruction of the annual schedules and movement patterns of individual animals requiresanalytical methods which provide estimates of daily locations, distances between the locations and the directionsof movement, withmeasures of their uncertainty.3. The new R package FLIGHTRmeets all these requirements. It enables refined and statistically validated estimationsof movement patterns of birds. Here, we present main features of this advanced package.