Spatial variation in songbird demographic trends from a regional network of banding stations in the Pacific NorthwestAuthor(s): Sarah M. Rockwell; John D. Alexander; Jaime L. Stephens; Robert I. Frey; C. John Ralph
Source: The Condor. 119(4): 732-744
Publication Series: Scientific Journal (JRNL)
Station: Pacific Southwest Research Station
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Many North American landbird populations have declined in recent decades, including those that occupy Western forest habitats. Long-term monitoring of abundance and vital rates allows us to detect species and habitats of concern, and to identify potential management actions. Here, we analyze capture data from a regional network of 10 banding sites in the Klamath-Siskiyou Bioregion, USA, to examine demographic trends for 12 Western forest bird species from 2002 to 2013. Adult abundance declined significantly in some breeding populations of Audubon's Yellow-rumped Warbler (Setophaga coronata auduboni) and Purple Finch (Haemorhous purpureus), and near-significantly in Oregon Dark-eyed Junco (Junco hyemalis oreganus). We observed significant declines in productivity of the Purple Finch and Spotted Towhee (Pipilo maculatus). Black-headed Grosbeaks (Pheucticus melanocephalus) and Yellow-breasted Chats (Icteria virens) increased significantly in adult abundance, but with variation among sites. Productivity in one year was positively correlated with adult abundance in the following year for only one species, suggesting that local productivity may not be the proximate demographic cause of population change. Trends in adult abundance were generally heterogeneous across the landscape, while trends in productivity were more consistent among sites. Ten of 12 bird species exhibited similar or more positive trends in the Klamath-Siskiyou Bioregion than in the larger Pacific Northwest region as measured by Breeding Bird Survey data. Data from long-term banding sites that include productivity indices and breeding status of adults can provide important supplementary information to other long-term monitoring data and help to generate hypotheses regarding proximate demographic causes of local population trends. Future studies using regional networks of banding sites may begin to elucidate source–sink dynamics and the scale at which they operate, a topic with implications for species conservation.
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CitationRockwell, Sarah M.; Alexander, John D.; Stephens, Jaime L.; Frey, Robert I.; Ralph, C. John. 2017. Spatial variation in songbird demographic trends from a regional network of banding stations in the Pacific Northwest. The Condor. 119(4): 732-744. https://doi.org/10.1650/CONDOR-17-44.1.
Keywordsabundance, banding, Breeding Bird Survey, long-term monitoring, mist netting, population trends, productivity, Western birds
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