Breeding Destinations and Spring Migration Patterns of Swainson's Thrush (Catharus ustulatus) at a Costa Rican Stopover Site

Stable-isotope analysis of feathers has become a useful tool for examining migration patterns and annual connectivity of migratory songbird populations. We used this approach, combined with molecular sex-identification, to examine expected breeding destinations and migration ecology of Swainson'...

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Bibliographic Details
Published in:The Auk 2008-01, Vol.125 (1), p.95-104
Main Authors: Wilson, Scott, Hobson, Keith A, Collister, Douglas M, Wilson, Amy G
Format: Article
Language:English
Subjects:
Animal behavior
Animal breeding
Aviculture
Bird migration
Birds
Boreal forests
Breeding
breeding destinations
Breeding sites
Catharus ustulatus
Costa Rica
Deuterium
Feathers
migration ecology
Migratory birds
Mountains
Polymerase chain reaction
Research s
Seasonal migration
Songbirds
stable isotopes
Studies
Swainson's Thrush
Warblers
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Summary:Stable-isotope analysis of feathers has become a useful tool for examining migration patterns and annual connectivity of migratory songbird populations. We used this approach, combined with molecular sex-identification, to examine expected breeding destinations and migration ecology of Swainson's Thrush (Catharus ustulatus) at a spring stopover site on the Osa Peninsula of Costa Rica. The number of individuals passing through the site increased in late March and peaked in mid-April before declining toward late April. Plumage and expected feather-deuterium (δDf) values for North America indicated that most individuals had probably bred or fledged in west-central regions of the boreal forest and western mountains, rather than farther north in the Yukon and Alaska or in eastern regions of Canada and the United States. Average δDf values differed little between males and females, indicating similar breeding destinations, though females tended to show greater variability. The δDf values of second-year and after-second-year birds differed only slightly, which suggests that most adults molted near the breeding grounds. Timing of migration through the site was not related to breeding latitude as inferred from feather δD. We also found little relation between the energetic reserves carried by individuals and their expected breeding destination, possibly because the reserves carried at this stage have little relation to the total reserves needed by northern breeders for the final stage of migration. Destinos de Cría y Patrones de Migración de Primavera de Catharus ustulatus en un Sitio de Escala en Costa Rica
ISSN:0004-8038
1938-4254
2732-4613
DOI:10.1525/auk.2008.125.1.95