Abstract

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.