Population trends of North American sea ducks as revealed by the Christmas Bird Count
Held August 23-27, 2005, at University of California, Santa Barbara.
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Abstract
Relative to other waterfowl, sea ducks are not well understood, yet evidence from a variety of analyses suggests that as many as 10 of the 15 species of North American sea ducks may be declining in population. However, because of the difficulty of conducting surveys of breeding populations and the lack of range-wide winter surveys, few data are available to assess the population trends of sea ducks with confidence. We analyze Audubon Christmas Bird Count data using hierarchical modeling methods that control for varying effort among circles and over time. These procedures allow us to assess early-winter relative density patterns among states and Bird Conservation Regions (BCRs) while also assessing trends in these regions and across the species North American range. Over the interval 1966 - 2003, continent-wide declines were observed in 1 of 11 species (the White-winged Scoter; -3.7%/yr). We compare CBC results to estimates of population change derived from the midwinter waterfowl survey conducted by the US Fish and Wildlife Service. The CBC does not effectively sample offshore populations of sea ducks; however, the CBC data can be used to assist in development of species-specific surveys, and CBC data can be used in combination with additional offshore sampling programs to better sample sea duck species.
Suggested Citation
Niven, D., Sauer, J., Butcher, G., 2005, Population trends of North American sea ducks as revealed by the Christmas Bird Count, chap. of One Hundred and Twenty-Third Stated Meeting of the American Ornithologists' Union: abstract book.
| Publication type | Book chapter |
|---|---|
| Publication Subtype | Book Chapter |
| Title | Population trends of North American sea ducks as revealed by the Christmas Bird Count |
| Year Published | 2005 |
| Language | English |
| Contributing office(s) | Patuxent Wildlife Research Center |
| Larger Work Type | Book |
| Larger Work Subtype | Other Government Series |
| Larger Work Title | One Hundred and Twenty-Third Stated Meeting of the American Ornithologists' Union: abstract book |
| First page | 133 (abstr |