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Concerns about the impact of plastics pollution on the environment have been growing since the 1970s. Marine debris has reportedly entangled and (or) been ingested by 914 marine species ranging from microinvertebrates to large marine mammals. Shorebirds have a high potential to be exposed to and ingest plastics pollution, as many species migrate long distances and periodically concentrate around shorelines, coastal areas, and estuaries that can have elevated levels of plastics pollution. Currently, little is understood about plastics exposure, frequency of occurrence (FO), and potential impacts relating to shorebirds. In this study, we catalogued and reviewed available studies across the globe that examined plastics pollution in shorebirds. We then quantified relevant traits of species and their environments to explore how shorebirds may be exposed to plastics pollution. Of 1106 samples from 26 shorebird species described within 16 studies that examined plastic ingestion, 53% of individuals contained some form of plastics pollution. Overall, Haematopodidae (oystercatchers) had the highest FO of plastics, followed by Recurvirostridae (avocets), Scolopacidae (sandpipers, phalaropes, godwits, and curlews), and Charadriidae (plovers). Plastics FO was much greater among species that migrated across marine areas (either oceanic or coastal) than those species that used continental flyways. Species that foraged at sea, on mudflats, or on beaches had higher average FO of plastic ingestion than species that foraged in upland or freshwater environments. Finally, species that used a sweeping foraging mode showed higher levels of ingested plastics and contained a far greater number of plastic pieces than all other techniques. These conclusions are based on a limited number of species and samples, with the distribution of samples skewed taxonomically and geographically. Using the combined knowledge of known shorebirds-plastics interactions and shorebird ecology, we present a hierarchical approach to identifying shorebirds that may be more vulnerable and susceptible to plastic ingestion. We provide recommendations on sampling protocols and future areas of research. Key words: plastic, pollution, marine litter, waders, shorebirds Les preoccupations en matiere d'impact de la pollution plastique sur l'environnement se sont accrues depuis les annees 1970. Les debris marins auraient entrave ou ete ingeres par 914 especes marines allant des micro-invertebres aux grands mammiferes marins. Les oiseaux de rivage sont tres susceptibles d'etre exposes a la pollution plastique et de lingerer, car de nombreuses especes migrent sur de longues distances et se concentrent periodiquement autour des rivages, des zones cotieres et des estuaires qui peuvent presenter des niveaux eleves de pollution plastique. A l'heure actuelle, on connait peu de choses sur l'exposition aux plastiques, la frequence et les impacts potentiels sur les oiseaux de rivage. Dans cette etude, les auteurs ont catalogue et synthetise les etudes disponibles a travers le monde qui se sont penchees sur la pollution plastique chez les oiseaux de rivage. Ils ont ensuite quantifie les caracteristiques pertinentes des especes et de leurs environnements afin d'explorer comment les oiseaux de rivage peuvent etre exposes a la pollution plastique. Sur 1106 echantillons provenant de 26 especes d'oiseaux de rivage decrites dans 16 etudes qui ont examine l'ingestion de plastiques, 53 % des individus comportaient une certaine forme de pollution plastique. Dans l'ensemble, les Haematopodidae (huitriers) presentaient la frequence d'occurrence (FO) la plus elevee de plastiques, suivis des Recurvirostridae (avocettes), des Scolopacidae (becasseaux, phalaropes, barges, courlis) et des Charadriidae (pluviers). La FO de plastiques etait beaucoup plus importante chez les especes qui migraient a travers les zones marines (oceaniques ou cotieres) que chez les especes qui utilisaient les voies de migration continentales. Les especes qui se nourrissaient en mer, dans les vasieres ou sur les plages presentaient une FO moyenne d'ingestion de plastiques plus elevee que les especes qui se nourrissaient dans les environnements de hautes terres ou d'eau douce. Enfin, les especes qui utilisaient un mode de recherche de nourriture par balayage presentaient des niveaux plus eleves d'ingestion de plastiques et contenaient un nombre beaucoup plus important de morceaux de plastique que celles qui utilisaient toutes les autres techniques. Ces conclusions sont basees sur un nombre limite d'especes et d'echantillons, la distribution des echantillons etant biaisee sur le plan taxonomique et geographique. En utilisant les connaissances combinees des interactions connues entre les oiseaux de rivage et les plastiques et de l'ecologie des oiseaux de rivage, les auteurs presentent une approche hierarchique pour identifier les oiseaux de rivage qui pourraient etre plus vulnerables et susceptibles d'ingerer des plastiques. Ils formulent des recommandations sur les protocoles d'echantillonnage et les futurs domaines de recherche. [Traduit par la Redaction] Mots-cles : plastique, pollution, dechets marins, echassiers, oiseaux de rivage, Introduction Concerns about the impact of plastics pollution on the environment have been growing since the 1970s. Initially, plastics pollution was thought to be primarily distributed around heavily populated areas; [...]

Species distributions are often indicative of historical biogeographical events and contemporary spatial biodiversity patterns. The Harlequin Duck Histrionicus histrionicus is a sea duck of conservation concern that has a disjunct distribution, with discrete portions of its range associated with northern Pacific and Atlantic Ocean basins. Movement data indicate migratory connectivity within regions of each ocean basin but not cross‐continent dispersal, suggesting that genetic structuring could exist at multiple spatial scales. Little is known regarding the impacts of past vicariance events on the species phylogeographical structure and historical demography, or rates of gene flow at different spatial scales. We used data from microsatellite loci and mitochondrial DNA (mtDNA) sequences to quantify levels of genetic diversity within, and the extent of spatial genetic differentiation among locations sampled at multiple spatial scales across the species range. Samples were collected at nonbreeding locations, which represent groupings appropriate for characterizing genetically differentiated subgroups at regional and continental scales. Collectively, genetic data and coalescence modelling suggested that individuals colonized regions currently occupied within both ocean basins in the Holocene from a single refuge in the Atlantic. Further, it seems likely there was secondary contact with lineages derived from populations in Asia, based on the shallow species‐wide mtDNA phylogeny and high incidence of recently derived private mtDNA haplotypes. Estimates of inter‐location variance in microsatellite allele and mtDNA haplotype frequency were moderate and significant between western (Pacific – North America) and eastern (Atlantic – North America, Greenland and Iceland) ocean basins and among sampling groups within each ocean basin. Genetic differentiation among sampling groups was particularly evident at the species distributional margins in the Atlantic (Iceland) and the Pacific (Shemya Island) Ocean basins. Coalescent modelling results suggest that contemporary spatial genetic patterns in the species arose through the combined influences of secondary contact, shared ancestry and gene flow after the last glacial maxima. [ABSTRACT FROM AUTHOR]

Global climate change has altered the timing of seasonal events (i.e., phenology) for a diverse range of biota. Within and among species, however, the degree to which alterations in phenology match climate variability differ substantially. To better understand factors driving these differences, we evaluated variation in timing of nesting of eight Arctic‐breeding shorebird species at 18 sites over a 23‐year period. We used the Normalized Difference Vegetation Index as a proxy to determine the start of spring (SOS) growing season and quantified relationships between SOS and nest initiation dates as a measure of phenological responsiveness. Among species, we tested four life history traits (migration distance, seasonal timing of breeding, female body mass, expected female reproductive effort) as species‐level predictors of responsiveness. For one species (Semipalmated Sandpiper), we also evaluated whether responsiveness varied across sites. Although no species in our study completely tracked annual variation in SOS, phenological responses were strongest for Western Sandpipers, Pectoral Sandpipers, and Red Phalaropes. Migration distance was the strongest additional predictor of responsiveness, with longer‐distance migrant species generally tracking variation in SOS more closely than species that migrate shorter distances. Semipalmated Sandpipers are a widely distributed species, but adjustments in timing of nesting relative to variability in SOS did not vary across sites, suggesting that different breeding populations of this species were equally responsive to climate cues despite differing migration strategies. Our results unexpectedly show that long‐distance migrants are more sensitive to local environmental conditions, which may help them to adapt to ongoing changes in climate. [ABSTRACT FROM AUTHOR]

Baseline information about declining North American shorebird populations is essential to determine the effects of global warming at low-lying coastal areas of the Arctic and subarctic, where numerous taxa breed, and to assess population recovery throughout their range. We estimated population sizes on the Yukon–Kuskokwim Delta (YKD) in western Alaska on the eastern edge of the Bering Sea. We conducted ground-based surveys during 2015 and 2016 at 589 randomly selected plots from an area of 35,769 km2. We used stratified random sampling in 8 physiographic strata and corrected population estimates using detection ratios derived from double sampling on a subset of plots. We detected 11,110 breeding individuals of 21 taxa. Western Sandpiper (Calidris mauri), Red-necked Phalarope (Phalaropus lobatus), Dunlin (subspecies C. alpina pacifica), and Wilson's Snipe (Gallinago delicata) were the most abundant taxa. We estimated that ~7 million individual shorebirds were breeding on the entire YKD in 2015 and 2016. Our surveys of this region provided robust population estimates (coefficient of variations ≤ 0.35) for 14 species. Our results indicate that the YKD supports a large proportion of North America's breeding populations of the Pacific Golden-Plover (Pluvialis fulva), the western population of a Whimbrel subspecies (Numenius phaeopus hudsonicus), a Bar-tailed Godwit subspecies (Limosa lapponica baueri), Black Turnstone (Arenaria melanocephala), a Dunlin subspecies (C. alpina pacifica), and Western Sandpiper. Our study highlights the importance of breeding shorebirds of this relatively pristine but climatically sensitive deltaic system. Estuaries and deltaic systems worldwide are rapidly being degraded by anthropogenic activities. Our population estimates can be used to refine prior North American population estimates, determine the effects of global warming, and evaluate conservation success by measuring population change over time. [ABSTRACT FROM AUTHOR]