| Patuxent Science Meeting 2006 Poster Abstract |
| | Population trends of sea ducks from the Christmas Bird Count and |
| | North American Breeding Bird Survey |
| | Niven, DK, Sauer JR, Butcher G |
| | Due to the difficulty of conducting range-wide surveys of either breeding or wintering populations, |
| | few data are available to assess the population trends of sea ducks with confidence. We |
| | analyze sea duck data from the Audubon Christmas Bird Count 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. |
| | Where sufficient data exist, we compare CBC results to estimates of population change derived |
| | from the USGS Breeding Bird Survey. 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 |
| | Friday, September 22, 2006 |