Migration patterns of San Francisco Bay Area Hermit Thrushes differ across a fine spatial scale
Effective conservation of short-distance migrants requires an understanding of intraspecific variation in migratory patterns across small spatial scales. Until the advent of ultra-light geolocation devices, our knowledge of the migratory connectivity of songbirds was limited. For the Hermit Thrush (...
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| Autores principales: | , , , , , |
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| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
De Gruyter
2016
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| Materias: | |
| Acceso en línea: | https://doaj.org/article/ffb9fc3b309b4504a870afefcca0e131 |
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| Sumario: | Effective conservation of short-distance migrants
requires an understanding of intraspecific variation in
migratory patterns across small spatial scales. Until the
advent of ultra-light geolocation devices, our knowledge of
the migratory connectivity of songbirds was limited. For the
Hermit Thrush (Catharus guttatus), subspecies delineations
and connectivity patterns have been unclear in the portion
of their breeding range in western North America from
southeastern Alaska to northwestern Washington, where
individuals wintering in the San Francisco Bay Area of
California purportedly breed. To determine breeding
locations and migratory timing of the Bay Area’s wintering
Hermit Thrushes, we deployed geolocators at sites to the
north and south of the San Francisco Bay. We compared
results from these two regions to one another and to
connectivity patterns suggested by subspecies definitions.
We collected morphometrics to identify regional differences.
Hermit Thrushes that wintered in the North Bay had a wider
and more southerly breeding distribution from the British
Columbia coast to northwestern Washington, whereas
South Bay thrushes migrated to southeastern Alaska and
the British Columbia coast. In general, North Bay thrushes
departed wintering grounds and arrived on breeding
grounds earlier than South Bay thrushes, but we cannot
eliminate sex as a factor in these differences. Regional
morphology differed only in bill length. Intraspecific
isolation in glacial refugia during the Late Pleistocene may
explain these fine-scale geographic variations in migration
patterns and morphology. |
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