Migratory Shorebirds Research Articles

Food Supply, Prey Selection and Estimated Consumption of Wintering Eurasian Curlews Feeding on Earthworms at Coastal Pastures

Coastal pastures provide supplementary foraging habitats for migratory shorebirds that rely on intertidal areas outside the breeding season. However, their role as foraging grounds for shorebirds is poorly understood. Here, we assessed the food supply, prey size selection, foraging behaviour and estimated consumption of a migratory shorebird, the near-threatened Eurasian Curlew Numenius arquata, at two temperate coastal pastures in northern Spain. Wintering Curlews only fed on earthworms (Oligochaeta), the main food available at coastal pastures. Average density and biomass were 102.3 ± 22.2 earthworms/m2 and 5.8 ± 1.3 g AFDW/m2, respectively, and only the density of surface living (i.e. epigeic) earthworms declined at the end of the winter. This food supply was comparatively high with respect to the biomass available in other man-made coastal habitats used by shorebirds wintering in temperate regions. Unexpectedly, the density of Curlews was higher at the pasture with the lowest food availability, though it declined significantly throughout the season at this site. Interestingly, Curlews preferentially selected the smallest size class (<32.5 mm) of epigeic earthworms, implying that a trade-off between energy intake rate and other fitness components could exist. Estimated consumption by Curlews was consistent with observed reductions in earthworm densities at both sites, thus reflecting a robust interaction between Curlews and epigeic earthworms at these agroecosystems throughout the non-breeding season. Our results highlight the potential role of earthworm communities at coastal pastures as food supply for declining migratory shorebirds.

Comparing abundance distributions and range maps in spatial conservation planning for migratory species.

Most spatial conservation planning for wide-ranging or migratory species is constrained by poor knowledge of species' spatiotemporal dynamics and is only based on static species' ranges. However, species have substantial variation in abundance across their range and migratory species have important spatiotemporal population dynamics. With growing ecological data and advancing analytics, both of these can be estimated and incorporated into spatial conservation planning. However, there is limited information on the degree to which including this information affects conservation planning. We compared the performance of systematic conservation prioritizations for different scenarios based on varying the input species' distributions by ecological metric (abundance distributions versus range maps) and temporal sampling resolution (weekly, monthly, or quarterly). We used the example of a community of 41 species of migratory shorebirds that breed in North America, and we used eBird data to produce weekly estimates of species' abundances and ranges. Abundance distributions at a monthly or weekly resolution led to prioritizations that most efficiently protected species throughout the full annual cycle. Conversely, spatial prioritizations based on species' ranges required more sites and left most species insufficiently protected for at least part of their annual cycle. Prioritizations with only quarterly species ranges were very inefficient as they needed to target 40% of species' ranges to include 10% of populations. We highlight the high value of abundance information for spatial conservation planning, which leads to more efficient and effective spatial prioritization for conservation. Overall, we provide evidence that spatial conservation planning for wide-ranging migratory species is most robust and efficient when informed by species' abundance information from the full annual cycle.

Egg Exhumation and Transport on a Foreshore Under Wave and Swash Processes

Several aquatic species use beach foreshores to lay their eggs. Understanding the dynamics of egg entrainment versus egg retention in foreshore sediment is important to delivering eggs to foraging species, and to predicting fecundity and population responses of beach nesting species to harvest and habitat management. Exhumation of these eggs is primarily by bioturbation and wave action. This study isolates effects of wave and swash processes on exhumation, entrainment, and transport of horseshoe crab eggs by conducting a 1-day field study designed to avoid effects of bioturbation by spawning and migratory shorebird predation. Dyed sand and horseshoe crab (Limulus polyphemus) eggs were injected into the foreshore of an estuarine beach in Delaware Bay, USA and sampled during 110 swash events using streamer traps. Significant wave heights ranged from 0.30 to 0.47 m. The quantity of eggs exhumed from the mid-foreshore by waves and swash was 3.8 times greater than from the upper foreshore where activation was by swash alone. Swash flows were skewed offshore, but egg transport was predominantly onshore from bore collapse. Egg release was greatest in early rising tide, making this the most productive time for shorebird foraging. Release of eggs from mid-foreshore may be dominated by wave action during high energy days with little spawning or by bioturbation by horseshoe crabs during intensive spawning. Activation depths in the swash were low, indicating that eggs buried on the upper foreshore can reach later stages of development after spawning ceases.

An artificial site provides valuable additional habitat to migratory shorebirds in a tropical harbour

Migratory shorebirds are declining in all transequatorial flyways, most rapidly in the East Asian–Australasian Flyway. Population trends for shorebirds have been derived at a flyway and continental scale, but changes at the local scale are less well understood. Here we compare trends in migratory shorebird populations using natural and artificial roost sites within a tropical harbour, examine possible drivers of change, and identify appropriate conservation management responses. Counts of 19 migratory shorebird species from 2010 and 2018 showed that total abundance increased at an average annual rate of 3.3% (95% CI=1.3–5.4%, P=0.001) across five natural roost sites. This was driven largely by increases in great knot, with most other species declining. At an artificial site in an adjacent shorebird area, total abundance increased at an average annual rate of 14.5% (95% CI=10.5–18.6%, P ≤ 0.000), with few species declining. These results suggest that there is a need to include both natural and artificial sites within shorebird conservation and management planning and that trends in different species can be driven by a combination of local and external drivers.

Keeping safe and fed: large heterospecific shorebird flocks to decrease intraspecific competition

Shorebirds join cohesive flocks for safety. The joining of individuals of several species in large heterospecific flocks can optimise individual vigilance and foraging. However, a large number of conspecific individuals in flocks may deplete food resources and increase intraspecific competition. In the present study, we argue that Nearctic–Neotropical migratory shorebird species join large heterospecific flocks in a balanced number as a way of controlling intraspecific competition. We recorded monospecific and heterospecific flocks in urban beaches from southeastern Brazil and annotated the species richness and the number of individuals per bird species per flock. Besides, we recorded the number of people around shorebird flocks to examine any relationship with flock size. We also recorded the foraging rate of the semipalmated plover Charadrius semipalmatus, a common migrant species in the region, as a species model to test competition and vigilance. We hypothesised that this species would exhibit a low foraging rate in scenarios with high intraspecific competition (i.e. large flocks with a high number of conspecifics) and high density of people, which may disturb birds. In the initial results, the density of people did not influence size of monospecific and heterospecific flocks; heterospecific flocks were larger than monospecific flocks, and heterospecific flocks increased in size by the addition of more species rather than more individuals of the same species. These data reflect a decrease in the relative abundance of individuals per species. Additionally, the semipalmated plover foraging rate was reduced in monospecific flocks, flocks with a high relative abundance (and total number) of the specific individuals and flocks surrounded by a high density of people. All these results indicate that shorebirds may adjust flock composition and size according to preferred foraging conditions, i.e. large and balanced heterospecific flocks with less intraspecific competition and less vigilance to potential predators in wintering areas.

Abundancia estival de aves costeras y mamíferos marinos en islas Desertores, comuna de Chaitén (Patagonia chilena)

Between 24th and 27th January of 2019, was sailed the sea of Desertores Islands, commune of Chaiten, region of Los Lagos, southern Chile. This with the objective of i) estimating the richness and abundance of birds and marine mammals in the area of influence of these islands, together with ii) identifying breeding sites. So, records were made on the richness, abundance and spatial distribution of birds and marine mammals observed during navigation, and also walking on Nihuel islet (42.626° S; 72.933° W) and Barraco islet (42.737° S; 73.065° W). It was determined that the species Brown-hooded gull (Chroicocephalus maculipennis), Imperial cormorant (Leucocarbo atriceps), kelp gull (Larus dominicanus) and Silvery grebe (Podiceps occipitalis), were the most abundant coastal birds. While the South American sea lion (Otaria flavescens) and Peale’s dolphin (Lagenorhynchus australis), were the most abundant marine mammals. At the spatial level, the highest concentrations of birds and marine mammals were found in the islets Nihuel and Barraco, as well as on the coast of Talcan Island. On the islet Nihuel nest at least 2100 pairs of Imperial cormorant, which makes this place one of the most important reproductive sites for this species in Chile. Also, there is a reproductive colony of South American fur seal (Arctocephalus australis), composed of at least 890 individuals. On the other hand, the Barraco islet is used by South American tern (Sterna hirundinacea) as a nesting site, together with an interesting group of migratory shorebirds.

Defining Human Disturbance to Shorebirds Using Manager and Scientist Input.

Shorebird researchers and land managers recognize human disturbance as a serious threat facing shorebirds. Yet, a common understanding of what defines human disturbance is lacking. To address this issue, we employed the Delphi technique, an iterative consensus-building social science method, to bring scientists and managers together to develop a shared definition of human disturbance and a list of priority human activities that could affect migratory shorebirds. During four iterative rounds, participants with extensive knowledge on human disturbance to shorebirds from varying geographic locations within the Northeastern U.S. worked together to produce a shared understanding. Through analyzing participants' open-ended responses, we identified important themes for the definition. The participants then refined and ranked these themes through surveys, and the top-ranked themes were used to draft a final definition also reviewed by the participants. Participants provided 94 human activities in response to our request to list and describe all potential human disturbances that affect shorebirds during fall migration. From there, we grouped the activities into 23 categories. Through rating and ranking tasks, participants reduced this list to 12 priority disturbance categories that represent the perceived most significant human disturbances in the Northeastern United States. We also compared responses among the different participant groups (i.e., managers, scientists, and manager/scientists), finding that groups' responses generally did not significantly differ. While nearly all participants were satisfied with the process, we provide some suggestions to improve it. The outputs of the Delphi technique have informed a best practices guidance document for shorebird management.

Differential exploitation of a single dominant prey species by migratory shorebirds – a preliminary observation from the vulnerable sandy beaches of the southwest coast of India

Observations on the food resources of migratory shore birds in selected sandy shores of Kerala on the southwest coast of India revealed that their main prey resource is a single species of sand crab (mole crab), Emerita holthuisi Sankolli, 1965, the major crustacean resource in the narrow stretches of sandy shores of central Kerala. Three sandy beaches flanking tidal estuaries, abundant in shore crabs, were selected as the representative sites to study in detail the feeding of shorebirds on the sand crabs. We observed the presence of mole crabs for a year and noted that they are found almost year round on these shores. The shore birds were found to exploit them during their wintering months from October to February. The variations in adaptations of 8 species of predatory shore birds in preying on E. holthuisi were also noted. The same predator-prey relationship was observed in similar small stretches of sandy shores in other parts of central Kerala also.

No evidence for an association between Clock gene allelic variation and migration timing in a long-distance migratory shorebird (Limosa lapponica baueri).

The gene Clock is a key part of the Core Circadian Oscillator, and the length of the polyglutamine (poly-Q) repeat sequence in Clock (ClkpolyQcds) has been proposed to be associated with the timing of annual cycle events in birds. We tested whether variation in ClkpolyQcds corresponds to variation in migration timing in the bar-tailed godwit (Limosa lapponica baueri), a species in which individuals show strong annual consistency in their migration timing despite the New Zealand population migrating across a 5-week period. We describe allelic variation of the ClkpolyQcds in 135 godwits over-wintering in New Zealand (N.Z.) and investigate whether polymorphism in this region is associated with northward migration timing (chronophenotype) from N.Z. or (for 32 birds tracked by geolocator) after the primary stopover in Asia. Six Clock alleles were detected (Q7‒Q12) and there was substantial variation between individuals (heterozygosity of 0.79). There was no association between ClkpolyQcds polymorphism and migration timing from N.Z. The length of the shorter Clock allele was related to migration timing from Asia, though this relationship arose largely from just a few northern-breeding birds with longer alleles. Other studies show no consistent associations between ClkpolyQcds and migration timing in birds, although Clock may be associated with breeding latitude in some species (as an adaptation to photoperiodic regime). Apparent relationships with migration timing could reflect latitude-related variation in migration timing, rather than Clock directly affecting migration timing. On current evidence, ClkpolyQcds is not a strong candidate for driving migration timing in migratory birds generally.

Nest Survival of Black-Necked Stilts (Himantopus mexicanus) on the Upper Texas Coast, USA

The Black-necked Stilt (Himantopus mexicanus) is a migratory shorebird of temperate and tropical America. Declining wetland quality and associated declines in hydrological integrity may contribute to widespread habitat loss for stilts nesting on the upper Texas Gulf of Mexico coast of the USA, as both fresh and brackish marshes are converting to open water and saline marsh. Nests (n = 356) were monitored in three wetland types on the upper Texas coast from 21 April-30 June 2011-2012. Of these 356 nests, 151 were located in managed freshwater wetlands (16 in 2011 and 135 in 2012), 128 were located in managed intermediate wetlands (75 in 2011 and 53 in 2012), and 77 were located in rice fields (all in 2012). Collectively, nest success was 0.2% (0 in rice fields and as high as 4.3% in freshwater wetlands in 2012), among the lowest ever reported for the species. The most frequent cause of nest failure was predation by mammalian and avian predators (∼50%). Daily nest survival rate was positively related to mudflat nesting substrates and negatively related to colony size, rice field, and brackish coastal wetland habitats. Future efforts to minimize edge effects in managed wetlands may prove valuable to improve nest success of stilts and other species that nest in similar wetland types.

Decreased nest survival associated with low temperatures in a high-elevation population of Mountain Plover (Charadrius montanus)

Mountain Plovers (Charadrius montanus) are migratory shorebirds of conservation concern that breed on grasslands and xeric tablelands scattered along the western edge of the Great Plains. Previous research from populations breeding on lower-elevation sites in Colorado and Montana suggests nest survival increases in cooler, drier environmental conditions. However, no studies have estimated Mountain Plover nest survival on high-elevation habitats, which have distinctively different climate and nesting phenology; therefore, it is unclear if these general trends hold true for the species as a whole or are regionally specific. In this study, we monitored nests of a population of Mountain Plovers breeding at high elevation in South Park, Colorado, to study influences on daily nest survival as compared to those found in literature from lower-elevation breeding sites. In contrast to studies on lower-elevation sites where daily maximum temperatures limited nest survival, we found daily minimum temperature best predicted variation in daily nest survival in South Park; survival odds declined with decreasing temperature. These results suggest that negative effects of extreme temperatures (hot or cold) may be generalities that exist between locales but are potentially mediated through different mechanisms at varying temporal scales. Although we cannot definitively conclude from our study why minimum temperature is associated with lower nest survival, we suggest alterations in incubation behavior may be a plausible mechanism that warrants future study. Overall, our study demonstrates the importance of considering differences between weather and phenology among breeding locations when estimating nest survival effects.

Composition and Drivers of Gut Microbial Communities in Arctic-Breeding Shorebirds.

Gut microbiota can have important effects on host health, but explanatory factors and pathways that determine gut microbial composition can differ among host lineages. In mammals, host phylogeny is one of the main drivers of gut microbiota, a result of vertical transfer of microbiota during birth. In birds, it is less clear what the drivers might be, but both phylogeny and environmental factors may play a role. We investigated host and environmental factors that underlie variation in gut microbiota composition in eight species of migratory shorebirds. We characterized bacterial communities from 375 fecal samples collected from adults of eight shorebird species captured at a network of nine breeding sites in the Arctic and sub-Arctic ecoregions of North America, by sequencing the V4 region of the bacterial 16S ribosomal RNA gene. Firmicutes (55.4%), Proteobacteria (13.8%), Fusobacteria (10.2%), and Bacteroidetes (8.1%) dominated the gut microbiota of adult shorebirds. Breeding location was the main driver of variation in gut microbiota of breeding shorebirds (R2 = 11.6%), followed by shorebird host species (R2 = 1.8%), and sampling year (R2 = 0.9%), but most variation remained unexplained. Site variation resulted from differences in the core bacterial taxa, whereas rare, low-abundance bacteria drove host species variation. Our study is the first to highlight a greater importance of local environment than phylogeny as a driver of gut microbiota composition in wild, migratory birds under natural conditions.

Serologic Evidence of Exposure to Highly Pathogenic Avian Influenza H5 Viruses in Migratory Shorebirds, Australia.

Highly pathogenic avian influenza (HPAI) H5Nx viruses of the goose/Guangdong/96 lineage continue to cause outbreaks in poultry and wild birds globally. Shorebirds, known reservoirs of avian influenza viruses, migrate from Siberia to Australia along the East-Asian-Australasian Flyway. We examined whether migrating shorebirds spending nonbreeding seasons in Australia were exposed to HPAI H5 viruses. We compared those findings with those for a resident duck species. We screened >1,500 blood samples for nucleoprotein antibodies and tested positive samples for specific antibodies against 7 HPAI H5 virus antigens and 2 low pathogenicity avian influenza H5 virus antigens. We demonstrated the presence of hemagglutinin inhibitory antibodies against HPAI H5 virus clade 2.3.4.4 in the red-necked stint (Calidris ruficolis). We did not find hemagglutinin inhibitory antibodies in resident Pacific black ducks (Anas superciliosa). Our study highlights the potential role of long-distance migratory shorebirds in intercontinental spread of HPAI H5 viruses.

Guest Introduction: More-than-human contact zones

Mary Louise Pratt used the term “contact zones” to describe those spaces where “cultures, meet, clash and grapple with each other, often in contexts of highly asymmetrical relations of power, such as colonialism, slavery, or their aftermaths as they are lived out in many parts of the world today”. Building on three sessions at the 2017 American Association of Geographers’ Annual Meeting, this special section features articles which apply Pratt’s concepts to environmental research. We argue that these articles demonstrate a “more-than-human ‘contact’ approach” to (1) better account for nonhuman agency by multiplying perspectives, (2) intervene in cases of violence and injustice, and (3) decolonize knowledge/production. Included are empirical case studies which describe encounters with the nonhuman; these include a postcolonial reading of the BBC’s Blue Planet II, a feminist science study of migratory shorebird conservation on New Jersey’s Delaware Bayshore, and political ecologies of prescribed forest burns by Parks Canada and tidal energy production in the Bay of Fundy. These articles broaden the definitions of “contact” and “justice” as they direct critical attention to the politics of environmental knowledge production, technoscientific means of understanding and managing the living environment, and forms of resistance to the exclusive governance of “wild” spaces. They present sites of environmental management and exploration as places of transformation, co-presence, unpredictability, and often intimate violence. The section demonstrates how political ecologies and more-than-human geographies expand Pratt’s “contact” perspective. An afterword is provided by Mary Louise Pratt.

Differential Change in Hippocampal Radial Astrocytes and Neurogenesis in Shorebirds With Contrasting Migratory Routes.

Little is known about environmental influences on radial glia-like (RGL) α cells (radial astrocytes) and their relation to neurogenesis. Because radial glia is involved in adult neurogenesis and astrogenesis, we investigated this association in two migratory shorebird species that complete their autumnal migration using contrasting strategies. Before their flights to South America, the birds stop over at the Bay of Fundy in Canada. From there, the semipalmated sandpiper (Calidris pusilla) crosses the Atlantic Ocean in a non-stop 5-day flight, whereas the semipalmated plover (Charadrius semipalmatus) flies primarily overland with stopovers for rest and feeding. From the hierarchical cluster analysis of multimodal morphometric features, followed by the discriminant analysis, the radial astrocytes were classified into two main morphotypes, Type I and Type II. After migration, we detected differential changes in the morphology of these cells that were more intense in Type I than in Type II in both species. We also compared the number of doublecortin (DCX)-immunolabeled neurons with morphometric features of radial glial–like α cells in the hippocampal V region between C. pusilla and C. semipalmatus before and after autumn migration. Compared to migrating birds, the convex hull surface area of radial astrocytes increased significantly in wintering individuals in both C. semipalmatus and C. pusilla. Although to a different extent we found a strong correlation between the increase in the convex hull surface area and the increase in the total number of DCX immunostained neurons in both species. Despite phylogenetic differences, it is of interest to note that the increased morphological complexity of radial astrocytes in C. semipalmatus coincides with the fact that during the migratory process over the continent, the visuospatial environment changes more intensely than that associated with migration over Atlantic. The migratory flight of the semipalmated plover, with stopovers for feeding and rest, vs. the non-stop flight of the semipalmated sandpiper may differentially affect radial astrocyte morphology and neurogenesis.

Factors promoting the recolonization of Oahu, Hawaii, by Bristle-thighed Curlews

Suitable habitat for Arctic-breeding migratory shorebirds is decreasing at their traditional wintering islands and atolls in the Central Pacific Flyway (i.e., Oceania) due to habitat degradation, reclamation, and sea-level rise. To maintain the size and resiliency of their populations, migratory shorebirds will need to expand their winter ranges by either colonizing new sites or recolonizing old sites from which they were extirpated. Bristle-thighed Curlews (Numenius tahitiensis) are long-distance migratory shorebirds that breed only in Alaska and winter across a vast region of the Central Pacific, typically on remote, unpopulated islands and atolls. Historically, Bristle-thighed Curlews were considered uncommon transients on the main Hawaiian Islands, but in the mid-1990s, curlews became regular visitors to Oahu and subsequently began wintering at the James Campbell National Wildlife Refuge on Oahu Island in Hawaii. Curlew numbers at this site grew steadily from <5 birds in the mid-1990s to an estimated 126 winter residents (95%CI 108–147) in 2013–2014. Timing of the recolonization event coincided with the establishment of a fenced pond complex that was managed for endangered waterbirds by maintaining areas of shallow water and low vegetation. High rates of apparent annual survival exhibited by adults and subadults (0.86–0.95) confirmed the suitability of the Refuge to curlews. Our results suggest that curlews in Oceania can naturally recolonize wintering islands, a trait that may be key to the survival of this species of conservation concern in an era of rising sea levels.

Predictable shorebird departure patterns from a staging site can inform collision risks and mitigation of wind energy developments

High‐quality staging sites are critical for long‐distance migratory shorebirds to rest and refuel but are under threat from human development, including expansion of wind energy projects. However, predicting migration timing and movements in relation to weather conditions at staging sites can increase our understanding and mitigate effects of wind turbine collisions. Here we assessed northward migration timing and orientation in relation to environmental conditions at an inland staging area in Saskatchewan, Canada, with active and proposed wind energy developments. The area is known to host ~25% of North America's Sanderling Calidris alba population and 16 other Arctic‐breeding migrant shorebird species. We quantified arrival and departure time of day in relation to weather using data from 140 of 237 Sanderlings radiotagged locally and at a southern staging site in the Gulf of Mexico with the Motus Wildlife Tracking System (April–June, 2015–2017). Although Sanderling arrival times were not related to time of day or weather, departures were more likely at sunset in winds blowing towards the northwest at intermediate speeds (&lt;22 km/h). Departure flights were also primarily oriented north‐northwest in the direction of a proposed wind energy development site at a mean ground speed of 21.4 m/s. Based on published climb rates and flight speed data, we estimated that shorebirds needed between 2 and 14 km setback distance to clear maximum turbine heights of 165 m. Given that departure events were predictable in time and space, adaptive mitigation may be useful for planning wind energy developments while reducing risk for staging Arctic‐breeding shorebirds.

Diversity and Abundance of Waterbird Communities in the Jaffna and Kilinochchi Districts: Where do we have to go from here?

Wetlands and waterbirds are inseparable elements. The preliminary study was conducted in eight sites, namely Mandaitivu, Mankumban, Kayts, Kavutharimunai, Pallai, Thadduvankoddy, Kapputhu and Nagarkovil in the Jaffna and Kilinochchi Districts of the northern region of Sri Lanka to determine the diversity and abundance of waterbirds. In each site, three counting blocks in length of 500 m with open width was selected for bird counting. Each block was separated at least by length of 500 m to avoid double counting. The counting of birds was done once a month from December, 2016 to May, 2017. Eighteen waterbird families were recorded. Phoenicopteridae, Anatidae and Scolopacidae were the dominant families. The presence of critically endangered species such as Spot-billed Duck (Anas poecilorhyncha) suggests the importance of conservation of these habitats. Two-way ANOVA indicated that waterbird families were significantly different among eight sites. The highest species richness was found in Kapputhu (57) and the lowest in Kavutharimunai (26). This study revealed that Mandaitivu, Mankumban, Kayts, Thadduvankoddy and Kapputhu are the excellent places to observe both migrant ducks and flamingos. Likewise Kavutharimunai is good for migrant shorebirds and seabirds by ferry while Nagarkovil and Kapputhu are suitable for viewing both feeding and roosting of waterbirds. On the whole this paper reveals that the northern region of Sri Lanka possess not only the potential of avitourism but also will become the hotspot of future bird researches, especially on waterbirds.

Mechanisms driving phenological and range change in migratory species.

Many migratory systems are changing rapidly in space and time, and these changes present challenges for conservation. Changes in local abundance and site occupancy across species' ranges have raised concerns over the efficacy of the existing protected area networks, while changes in phenology can potentially create mismatches in the timing of annual events with the availability of key resources. These changes could arise either through individuals shifting in space and time or through generational shifts in the frequency of individuals using different locations or on differing migratory schedules. Using a long-term study of a migratory shorebird in which individuals have been tracked through a period of range expansion and phenological change, we show that these changes occur through generational shifts in spatial and phenological distributions, and that individuals are highly consistent in space and time. Predictions of future rates of changes in range size and phenology, and their implications for species conservation, will require an understanding of the processes that can drive generational shifts. We therefore explore the developmental, demographic and environmental processes that could influence generational shifts in phenology and distribution, and the studies that will be needed to distinguish among these mechanisms of change.This article is part of the theme issue ‘Linking behaviour to dynamics of populations and communities: application of novel approaches in behavioural ecology to conservation’.

Conserving unprotected important coastal habitats in the Yellow Sea: Shorebird occurrence, distribution and food resources at Lianyungang

The Yellow Sea coastline in East Asia, an important staging area for migratory shorebirds in the East Asian-Australasian Flyway (EAAF), is rapidly deteriorating. Conserving the declining shorebird populations that rely on the Yellow Sea requires habitat protection and management based on sound ecological knowledge, especially on the seasonal occurrence of shorebirds, their daily movements and their food resources. However, in this region such ecological data are scarce, and expertise to collect them are less-established. Here we gather and assimilate such information for the coastal wetlands at Lianyungang on the Chinese Yellow Sea coast, an understudied and unprotected area where we found 27% of intertidal soft sediment habitats have been destroyed in 2003–2018 by reclamation. In 2008–2018, 43 shorebird species were recorded along this coastline, including 12 globally threatened or ‘Near Threatened’ species. In terms of number of shorebird species exceeding 1% of the EAAF population, with 22 species meeting this criterion, Lianyungang ranks highest among the >300 shorebird sites in East Asia. The benthic mollusc community of the intertidal flats were dominated by small soft-shelled bivalve species at very high densities, including 9399 individuals/m2 of Potamocorbula laevis, which are high-quality food for shorebirds to refuel during migration. Satellite tracked bar-tailed godwits (Limosa lapponica) and great knots (Calidris tenuirostris) stopped at Lianyungang for 5–30 days during northward and southward migration. The tidal movements of satellite-tagged birds indicated high-tide roosts and low-tide foraging areas, some of which are inaccessible on-ground. These movements can also be used to evaluate whether roosts and foraging areas are close enough to each other, and direct where to create new roost sites. Potential measures to increase the capacity of Lianyungang to support shorebirds include reducing human disturbances, creating roosts at undeveloped parts of the reclaimed land, and removing recently-built sea dikes to restore intertidal flats.