Addressing urgent conservation issues, such as the drastic declines of North American migratory birds, requires creative, evidence-based, efficient, and collaborative approaches. The abundance of over 50% of monitored North American shorebird populations has declined by over 50% since 1980. To address these declines, we developed a partnership of scientists and practitioners called the Shorebird Science and Conservation Collective (hereafter the collective). The collective was founded to translate the combined findings of shorebird tracking data into on-the-ground conservation action. With advice from an advisory group, the collective acts as an intermediary whereby dedicated staff collate and analyze data contributions from scientists to support knowledge requests from conservation practitioners. In its first three years, data contributions from 75 organizations include over 7.1 million shorebird observations forming movement paths of 3420 individuals representing 36 species tracked across the Americas and have informed 18 conservation projects spanning education, land and species management, land conservation, and policy requests. Others engaged in translational science from big data could consider similar knowledge-sharing models that prioritize usable data products, foster collaborative engagement between science experts and practitioners, build focused communities around topics or taxonomic groups, and employ a proof-of-concept phase to develop scalable solutions while making progress toward long-term funding to sustain impact. As the volume of scientific data continues to grow, intermediaries, such as the collective, can be vital liaisons to rapidly integrate and interpret research to support conservation action. Dedicated to the memory of Shiloh Schulte and his conservation achievements for shorebirds.

Animal-borne trackers are commonly used to study bird movements, including in long-distance migrants such as shorebirds. Selecting a tracker and attachment method can be daunting, and methodological advancements often have been made by trial and error and conveyed by word of mouth. We synthesized tracking outcomes across 2745 dorsally mounted trackers on 37 shorebird species around the world. We evaluated how attachment method, power source, data retrieval method, relative tracker mass, and biological traits affected success, where success was defined as whether or not each tag deployment reached its expected tracking duration (i.e. all aspects succeeded for the intended duration of the study: attachment, tracking, data acquisition, and bird survival). We conducted separate analyses for tag deployments with remote data retrieval ('remote-upload tag deployments') and those that archived data and had to be recovered ('archival tag deployments'). Among remote-upload tag deployments, those that were a lighter mass relative to the bird, were beyond their first year of production, transmitted data via satellite, or were attached with a leg-loop harness were most often successful at reaching their expected tracking duration. Archival tag deployments were most successful when applied at breeding areas, or when applied to males in any season. Remote-upload tag deployments with solar power, satellite data retrieval, or leg-loop harnesses continued tracking for longer than those with battery power, other types of data retrieval, or glue attachments. However, the majority of tag deployments failed to reach their expected tracking duration (71% of remote-upload, 83% of archival), which could have been due to tracker failure, attachment failure, or bird mortality. Our findings highlight that many tag deployments may fail to meet the goals of a study if tracking duration is crucial. Using our results, we provide guidelines for selecting a tracker and attachment to improve success at meeting study goals.

Identifying the migration routes and stopover sites used by declining species is critical for developing targeted conservation actions. Long-distance migratory shorebirds are among the groups of birds declining most rapidly, yet we frequently lack detailed knowledge about the routes and stopover sites they use during their hemisphere-spanning migrations. This is especially true for species that migrate through mid-continental regions in the Western Hemisphere. We therefore used satellite transmitters to track 212 individuals of 6 shorebird species during their southward migrations-Pluvialis dominica (American Golden-Plover), Limosa haemastica (Hudsonian Godwit), Tringa flavipes (Lesser Yellowlegs), Calidris subruficollis (Buff-breasted Sandpiper), C. melanotos (Pectoral Sandpiper), and Bartramia longicauda (Upland Sandpiper)-as they crossed the Amazon Basin of South America, a region from which reports of shorebird numbers are increasing but remain relatively rare. Our results make clear that the Amazon Basin provides stopover habitat for a large number of shorebirds: more than 74% of individuals tracked crossing the Amazon Basin stopped over in the region for an average of 2-14 days, with some spending the entire nonbreeding season there. All species selected stopover sites along the region's many rivers and lakes, while within stopover sites each species exhibited distinct habitat preferences. The timing of stopovers within sub-basins of the Amazon Basin also coincided with periods of low water, when the muddy, shallow water habitats preferred by most shorebirds are likely plentiful. Together, our results highlight the need for detailed investigations into shorebird abundance and distribution within the Amazon Basin, threats to shorebirds within particular subbasins, and links between shorebird conservation efforts and those targeting the myriad other species that inhabit this dynamic, hyper-diverse region. center dot Long-distance migratory shorebirds are declining worldwide. For many of these species, we lack essential information about their habitats throughout the year, including the stopover sites they use during migration.center dot In the Western Hemisphere, information is particularly lacking for the midcontinent of South America, a region that several shorebird species may cross during their southward migrations.center dot We examine satellite tracking data from 6 shorebird species to show that stops in the Amazon Basin are surprisingly common, occurring in more than 74% of southward migratory tracks.center dot Shorebirds selected stopover sites along rivers and lakes and exhibited distinct local-scale habitat preferences. These results highlight the need for detailed investigations into shorebird abundance and stopover site characteristics within the Amazon Basin, as well as potential links to broader conservation efforts. Identificar las rutas migratorias y los sitios de parada utilizados por las especies en declive es crucial para desarrollar acciones de conservaci & oacute;n espec & iacute;ficas. Las aves playeras migratorias de larga distancia est & aacute;n entre los grupos de aves que disminuyen m & aacute;s r & aacute;pidamente, pero con frecuencia carecemos de conocimientos detallados sobre las rutas y los sitios de parada que utilizan durante sus migraciones de magnitud hemisf & eacute;rica. Esto es especialmente cierto para las especies que migran a trav & eacute;s de las regiones medio-continentales del Hemisferio Occidental. Por lo tanto, utilizamos transmisores satelitales para rastrear a 212 individuos de 6 especies de aves playeras durante sus migraciones hacia el sur-Pluvialis dominica, Limosa haemastica, Tringa flavipes, Calidris subruficollis, C. melanotos y Bartramia longicauda-mientras cruzaban la cuenca amaz & oacute;nica de Am & eacute;rica del Sur, una regi & oacute;n en la cual los estudios sobre el n & uacute;mero de aves playeras est & aacute;n aumentando, pero siguen siendo relativamente raros. Nuestros resultados dejan claro que la cuenca amaz & oacute;nica proporciona h & aacute;bitat de parada para un gran n & uacute;mero de aves playeras: m & aacute;s del 74% de los individuos rastreados que cruzaron la cuenca amaz & oacute;nica se detuvieron en la regi & oacute;n durante un promedio de 2 a 14 d & iacute;as, y algunos pasaron toda la temporada no reproductiva all & iacute;. Todas las especies seleccionaron sitios de parada a lo largo de los numerosos r & iacute;os y lagos de la regi & oacute;n, mientras que dentro de los sitios de parada cada especie mostr & oacute; preferencias de h & aacute;bitat distintas. El momento de las paradas dentro de las subcuencas de la cuenca amaz & oacute;nica tambi & eacute;n coincidi & oacute; con per & iacute;odos de aguas bajas, cuando los h & aacute;bitats de aguas poco profundas y fangosas preferidos por la mayor & iacute;a de las aves playeras son probablemente abundantes. En conjunto, nuestros resultados destacan la necesidad de investigaciones detalladas sobre la abundancia y distribuci & oacute;n de las aves playeras dentro de la cuenca amaz & oacute;nica, las amenazas a las aves playeras dentro de subcuencas particulares, y los v & iacute;nculos entre los esfuerzos de conservaci & oacute;n de las aves playeras y aquellos dirigidos a la mir & iacute;ada de otras especies que habitan esta regi & oacute;n din & aacute;mica y de gran diversidad.

The McKay ' s Bunting (Plectrophenax hyperboreus) is endemic to Alaska, breeds solely on the remote and uninhabited St. Matthew and Hall islands (332 km2) in the central Bering Sea, and is designated as a species of high conservation concern due to its small population size and restricted range. A previous hypothesized population estimate (similar to 2,800 to 6,000 individuals) was greatly increased (similar to 31,200 individuals) after systematic surveys of the species ' entire breeding range in 2003, establishing McKay ' s Bunting as one of the rarest passerines in North America. In 2018, we replicated the 2003 surveys and used density surface models to estimate breeding season densities, distributions, and population change over the intervening time period. Our results indicate that the McKay ' s Bunting population declined by 38% (95% CI: 27 to 48%) from similar to 31,560 to 19,481 individuals since 2003. Spatial model predictions showed no areas with an increase of birds on either St. Matthew or Hall islands but revealed declines across 13% (42 km(2)) of St. Matthew Island. Declines disproportionately occurred both in marginal habitats with reduced rocky nesting substrate and in high-density hotspots along the coast of St. Matthew Island. The total area occupied by breeding adults decreased by 8%, and high-density hotspots shifted inland from the coast of St. Matthew Island to higher elevations on both islands, the latter potentially responses to exceptionally warm weather and reduced spring snow cover in 2018. Additionally, we observed low numbers of predators and interspecific competitors in 2018, suggesting that these did not cause the decline. Our findings indicate that McKay ' s Bunting meets international standards for elevating its conservation status from Least Concern to Endangered based on the International Union for Conservation of Nature Red List of Threatened Species ranking criteria. Additional population monitoring and studies to identify the causal mechanisms of the recent population decline of this rare species could assist future population assessments.

Addressing urgent conservation issues, like the drastic declines of North American migratory birds, requires creative, evidence-based, efficient, and collaborative approaches. Over 50% of monitored North American shorebird populations have lost over 50% of their abundance since 1980. To address these declines, we developed a partnership of scientists and practitioners called the Shorebird Science and Conservation Collective (hereinafter “the Collective”). Here, we present this successful case study as an example for others engaged in translational science. The Collective acts as an intermediary whereby dedicated staff collate and analyze data contributions from scientists to support knowledge requests from conservation practitioners. Data contributions from 74 organizations include over 6.7 million shorebird locations forming movement paths of 3,345 individuals representing 36 species tracked across the Americas. We describe the founding and structure of the Collective and conservation activities we supported in our first two years. As the volume of scientific data on animal movements continues to grow, groups like the Collective can be vital liaisons to rapidly integrate and interpret research to support conservation action.### Competing Interest StatementThe authors have declared no competing interest.

Shorebirds have experienced a precipitous reduction in abundance over the past four decades. While some threats to shorebirds are widespread (e.g., habitat alteration), others are regional and may affect specific populations. Lesser Yellowlegs (Tringa flavipes) are long-distance migrants that breed across the North American boreal biome and have declined in abundance by 60-80% since the 1970s. The documented harvest of Lesser Yellowlegs in the Caribbean and northeastern South America during southward migration is a possible limiting factor for the species, but it is unknown to what extent birds from different breeding origins may be affected. To address the question of differential occurrence in harvest zones during southward migration, we used PinPoint GPS Argos transmitters to track the southward migrations of 85 adult Lesser Yellowlegs from across the species' breeding range and 80 degrees of longitude from Anchorage, Alaska, USA, to the Mingan Archipelago, Quebec, Canada. We classified migratory locations as inside or outside three zones with high levels of harvest (Caribbean, coastal Guianas, and coastal Brazil) and then fit generalized additive mixed models to estimate the probability of occurrence of Lesser Yellowlegs in harvest zones according to their breeding origin. Individuals from the Eastern Canada population had a higher probability of occurrence within one or more harvest zones and remained in those zones longer than individuals breeding in Alaska and western Canada. Linear regressions also suggested that longitude of the breeding origin is an important predictor of occurrence in harvest zones during southward migration. Lastly, our findings, combined with other sources of evidence, suggest that current estimated harvest rates may exceed sustainable limits for Lesser Yellowlegs, which warrants further investigation. Lay Summary center dot The Lesser Yellowlegs is experiencing a steep population decline. Addressing longstanding knowledge gaps, such as the potential impact that unregulated harvest has on specific breeding populations, helps scientists and managers develop and implement effective conservation actions for this vulnerable species. center dot Using GPS telemetry, we tracked the southward migration of 85 adult Lesser Yellowlegs across the Western Hemisphere to establish the specific populations that migrate through areas with high harvest. center dot Lesser Yellowlegs originating from the eastern part of their migratory range were more likely than western-breeding birds to occur within jurisdictions in the Caribbean and northeastern South America where shorebird harvest occurs. center dot Without considering differential occurrence of Lesser Yellowlegs within harvest regions, their decline will likely continue, resulting in the loss of biodiversity and an important cultural resource.

Black Turnstone is an obligate Pacific coast shorebird that is included as a “Species of High Concern” in both the U.S. and Alaska Shorebird Conservation Plans. Specific migration routes for this species are not well understood, which makes its recent disappearance at a major spring stopover site, northern Montague Island in Prince William Sound, Alaska, difficult to interpret. We tracked 23 Black Turnstones between breeding and wintering areas and examined migration timing, duration, and routes used. We identified two high-use regions during migration: 1) Cook Inlet/Shelikof Strait, Alaska, and 2) the Haida Gwaii Archipelago in British Columbia/Alexander Archipelago in southeastern Alaska. This second region was also an important wintering area. We found that northbound migration was longer than southbound (the reverse of what is often observed in shorebirds) and that staging behavior was primarily seen during northbound migration. No birds were tracked to northern Montague Island, and only a few individuals stopped anywhere in Prince William Sound. Alterations in patterns of spring herring spawn in Prince William Sound may be affecting the routes and stopovers used by Black Turnstones, and birds may be wintering farther north in recent decades due to warmer winter conditions. Additionally, the increasing availability and popularity of citizen science efforts like eBird has created a mechanism for disseminating observations from less accessible parts of the Black Turnstone range, a fact which may confound our understanding of whether migration routes for this species have changed over the last 30 years.

Abstract Many populations of long‐distance migrant shorebirds are declining rapidly. Since the 1970s, the lesser yellowlegs (Tringa flavipes) has experienced a pronounced reduction in abundance of ~63%. The potential causes of the species' decline are complex and interrelated. Understanding the timing of migration, seasonal routes, and important stopover and non‐breeding locations used by this species will aid in directing conservation planning to address potential threats. During 2018–2022, we tracked 118 adult lesser yellowlegs using GPS satellite tags deployed on birds from five breeding and two migratory stopover locations spanning the boreal forest of North America from Alaska to Eastern Canada. Our objectives were to identify migratory routes, quantify migratory connectivity, and describe key stopover and non‐breeding locations. We also evaluated predictors of southbound migratory departure date and migration distance. Individuals tagged in Alaska and Central Canada followed similar southbound migratory routes, stopping to refuel in the Prairie Pothole Region of North America, whereas birds tagged in Eastern Canada completed multi‐day transoceanic flights covering distances of >4000 km across the Atlantic between North and South America. Upon reaching their non‐breeding locations, lesser yellowlegs populations overlapped, resulting in weak migratory connectivity. Sex and population origin were significantly associated with the timing of migratory departure from breeding locations, and body mass at the time of GPS‐tag deployment was the best predictor of southbound migratory distance. Our findings suggest that lesser yellowlegs travel long distances and traverse numerous political boundaries each year, and breeding location likely has the greatest influence on migratory routes and therefore the threats birds experience during migration. Further, the species' dependence on wetlands in agricultural landscapes during migration and the non‐breeding period may make them vulnerable to threats related to agricultural practices, such as pesticide exposure.

Studies of the evolutionary causes and consequences of variation in circulating glucocorticoids (GCs) have begun to reveal how they are shaped by selection. Yet the extent to which variation in circulating hormones reflects variation in other important regulators of the hypothalamic-pituitary-adrenal (HPA) axis, and whether these relationships vary among populations inhabiting different environments, remain poorly studied. Here, we compare gene expression in the brain of female tree swallows (Tachycineta bicolor) from populations that breed in environments that differ in their unpredictability. We find evidence of inter-population variation in the expression of glucocorticoid and mineralocorticoid receptors in the hypothalamus, with the highest gene expression in a population from an extreme environment, and lower expression in a population from a more consistent environment as well as in birds breeding at an environmentally variable high-altitude site that are part of a population that inhabits a mixture of high and low altitude habitats. Within some populations, variation in circulating GCs predicted differences in gene expression, particularly in the hypothalamus. However, some patterns were present in all populations, whereas others were not. These results are consistent with the idea that some combination of local adaptation and phenotypic plasticity may modify components of the HPA axis affecting stress resilience. Our results also underscore that a comprehensive understanding of the function and evolution of the stress response cannot be gained from measuring circulating hormones alone, and that future studies that apply a more explicitly evolutionary approach to important regulatory traits are likely to provide significant insights.

Abstract The Olive-sided Flycatcher (Contopus cooperi) is a steeply declining aerial insectivore with one of the longest migrations of any North American passerine. We deployed light-level geolocators and archival GPS tags on breeders in boreal Alaska to determine migratory routes, important stopovers and non-breeding locations. Data from 16 individuals revealed a median 23,555 km annual journey (range: 19,387, 27,292 km) over 95 days (range: 83, 139 days) with wintering occurring in three regions of South America (NW Colombia/Ecuador, central Peru and W Brazil/S Peru). We developed a new method to identify “Important Stopovers” by quantifying intensity of use (a function of bird numbers and stop durations) along migratory routes. We identified 13 Important Stopovers that accounted for ~66% of the annual migratory period, suggestive of refueling activities. Some sites coincided with key areas previously identified for other Neotropical-Nearctic migrants. Percent land “protected” at Important Stopovers, as defined by IUCN, ranged from 3.8% to 49.3% (mean [95% CI]: 17.3% [9.6, 25.0]). Total migration speed did not differ by season (median: 255 km day-1, range: 182, 295km day-1), despite greater spring travel distances. Birds with longer non-breeding periods, however, migrated north faster. Climate-driven mismatches in migratory timing may be less of a concern for western than for eastern flycatcher populations, given recent con-generic analyses (C. sordidulus, C. virens). However, accelerated high-latitude changes, may nonetheless impact boreal breeders.

The Arctic is undergoing large-scale changes that are likely to accelerate in future decades such as introductions and expansions of invasive species. The Arctic is in a unique position to prevent new introductions and spread of existing invasive species by adopting policies and actions aimed at early detection. Responding to threats from invasive species to minimize impacts to ecosystems, communities, food security, and northern economies will necessitate extensive observations and monitoring, but resource managers often face decisions without having adequate data and resources at hand. Local observing programs such as citizen science and community-based monitoring programs present attractive methods for increasing observing capacity that span contributory and co-created approaches while raising awareness of an issue among stakeholders. While the co-created model has been widely applied and encouraged in the Arctic context, contributory citizen science programs offer an additional tool for addressing observing needs in the Arctic. We showcase three contributory citizen science programs related to freshwater, terrestrial, and marine environments that have supported the objectives of the Alaska Invasive Species Partnership. We discuss criteria for achieving ARIAS priority actions at the participant scale related to participants’ motivation and participants’ understanding of the value of their contributions, at the programmatic scale, for example promoting accessible, reciprocal, and transparent knowledge exchange, and at the policy and science scale where management action is data driven. The approach is aimed at successful integration of citizen science into Arctic policy making. Finally, we discuss challenges related to broader global data collection and future directions for contributory citizen science within Arctic observing networks.

PurposeThe purpose of this paper is to provide a conceptual framework for using citizen science – defined as a data collection method through which non-professionals engage in contributing to authentic scientific inquiry – within the expedition cruise industry to contribute significantly to the collection of environmental data from hard-to-access Arctic areas.Design/methodology/approachThe authors review trends in Arctic expedition cruise tourism and current needs in Arctic research and monitoring, and clarify where the expedition cruise tourism industry could have the most impact by providing data to the scientific community. The authors also compare the regulatory context in the Antarctic to that in the Arctic and discuss how these differences could affect the widespread use of citizen science. At last, the authors describe some general principles for designing citizen science programs to be successful on board, and highlight several existing programs that are being recognized for their contributions to a greater scientific understanding of the Arctic.FindingsThe authors find that citizen science data from the expedition cruise industry are underutilized as a tool for monitoring Arctic change. Numerous examples illustrate how citizen science programs on-board expedition ships can successfully collect robust scientific data and contribute to enhancing the knowledge and stewardship capacity of cruise passengers. Inclusion of citizen science data from the expedition cruise industry should be considered a critical part of international Arctic observing networks and systems.Social implicationsActive participation in Arctic citizen science by tourists on expedition cruise ships has many potential benefits beyond the collection of high quality data, from increasing passengers’ knowledge and understanding of the Arctic while on board, to affecting their attitudes and behaviors after they return home.Originality/valueThe potential for tourism to contribute to Arctic observing systems has been discussed previously in the scientific literature; the authors narrow the focus to citizen science programs in the expedition cruise industry, and provide concrete examples, in the hope that this will streamline acceptance and implementation of these ideas by researchers and tourism practitioners.

For more than 30 y, the Alaska Loon Watch (1985-1999) and the Alaska Loon and Grebe Watch (2000-2015) engaged citizen scientist participants to record more than 10,000 observations of common loons Gavia immer and Pacific loons Gavia pacifia at 346 lakes in five subregions of southcentral Alaska. We used generalized linear mixed models to estimate long-term trends in adult loon counts and chick survival and examined environmental variables associated with loon abundance. Adult common loon counts increased in all five subregions by 0.6-3.6% annually, whereas Pacific loons decreased 3% in the Anchorage subregion, but otherwise had trends not distinguishable from zero. Lake area was positively associated with common loon abundance and negatively associated with Pacific loon abundance. We also noted an inverse relationship between common loon and Pacific loon presence, consistent with the premise of interspecific competition. We did not find strong relationships between loon presence and predictor variables indicative of human disturbance or lakeshore development. Estimates of chick survival over time also revealed no clear pattern, although common loon chicks showed a decline in survival over the study period in one subregion. Citizen science programs provide agencies with a cost-effective tool to collect data over large spatial and temporal extents, which may not be feasible otherwise. However, there are ramifications of common data deficiencies associated with casual or unstructured observations, which can violate the assumptions required for rigorous statistical analysis. The implementation of a carefully predefined sampling protocol can avoid sampling bias, eliminate stringent assumptions, and ensure higher information content of citizen science data.

Kubelka et al. (Science, 9 November 2018, p. 680-683) claim that climate change has disrupted patterns of nest predation in shorebirds. They report that predation rates have increased since the 1950s, especially in the Arctic. We describe methodological problems with their analyses and argue that there is no solid statistical support for their claims.

Kubelka et al. (Reports, 9 November 2018, p. 680) claim that climate change has disrupted patterns of nest predation in shorebirds. They report that predation rates have increased since the 1950s, especially in the Arctic. We describe methodological problems with their analyses and argue that there is no solid statistical support for their claims.

Marking wild birds is an integral part of many field studies. However, if marks affect the vital rates or behavior of marked individuals, any conclusions reached by a study might be biased relative to the general population. Leg bands have rarely been found to have negative effects on birds and are frequently used to mark individuals. Leg flags, which are larger, heavier, and might produce more drag than bands, are commonly used on shorebirds and can help improve resighting rates. However, no one to date has assessed the possible effects of leg flags on the demographic performance of shorebirds. At seven sites in Arctic Alaska and western Canada, we marked individuals and monitored nest survival of four species of Arctic-breeding shorebirds, including Semipalmated Sandpipers (Calidris pusilla), Western Sandpipers (C. mauri), Red-necked Phalaropes (Phalarope lobatus), and Red Phalaropes (P. fielicarius). We used a daily nest survival model in a Bayesian framework to test for effects of leg flags, relative to birds with only bands, on daily survival rates of 1952 nests. We found no evidence of a difference in nest survival between birds with flags and those with only bands. Our results suggest, therefore, that leg flags have little effect on the nest success of Arctic-breeding sandpipers and phalaropes. Additional studies are needed, however, to evaluate the possible effects of flags on shorebirds that use other habitats and on survival rates of adults and chicks.

Semipalmated Sandpiper (Calidris pusilla) populations have undergone significant declines at core nonbreeding sites in northeastern South America. Breeding populations have also declined in the eastern North American Arctic, but appear to be stable or increasing in the central and western Arctic. To identify vulnerable populations and sites, we documented the migratory connectivity of Semipalmated Sandpipers using light-level geolocators, deploying 250 at 8 Arctic sites across the species' breeding range from 2011 to 2015, plus 87 at a single wintering site in northeastern Brazil in 2013 and 2014. We recovered 59 units and resighted 7 more (26% return rate) on the breeding grounds, but none at the nonbreeding site. We recovered only similar to 3% of units deployed in 2013 at eastern Arctic breeding sites, but recovered 33% of those deployed in 2015. Overall, birds with geolocators were 57% as likely to return as those carrying alphanumeric flags. Stopover durations at prairie sites (mean: 8.7 days southbound, 6.7 days northbound) were comparable with durations estimated by local banding studies, but geolocator-tagged birds had longer stopovers than previously estimated at James and Hudson Bay, the Bay of Fundy, and the Gulf of Mexico. Migration routes confirmed an eastern Arctic connection with northeastern South America. Birds from eastern Alaska, USA, and far western Canada wintered from Venezuela to French Guiana. Central Alaskan breeders wintered across a wider range from Ecuador to French Guiana. Birds that bred in western Alaska wintered mainly on the west coasts of Central America and northwestern South America, outside the nonbreeding region in which population declines have been observed. Birds that bred in the eastern Arctic and used the Atlantic Flyway wintered in the areas in South America where declines have been reported, whereas central Arctic-breeding populations were apparently stable. This suggests that declines may be occurring on the Atlantic Flyway and in the eastern Arctic region.