| Patuxent Science Meeting 2006 Poster Abstract |
| |
Breeding Bird Survey and distance sampling to estimate breeding bird density |
| | Somershoe SG, Twedt DJ, Reid B |
| | We combined Breeding Bird Survey point count protocol and distance sampling to survey spring |
| | migrant and breeding birds within Vicksburg National Military Park on 33 days between March |
| | and June of 2003 and 2004. For 25 of 106 detected species, we used program Distance to |
| | estimate detection probabilities and densities from 660 three-minute point counts where bird |
| | detections were recorded within four distance annuli. For most species, density estimates were |
| | improved through incorporation of survey date and proportion of forest cover at point count |
| | locations as covariates. Distance sampling provided densities that were markedly greater and |
| | less variable than relative abundances estimated from point count data that were uncorrected for |
| | probability of detection. Our results suggest Breeding Bird Surveys would benefit from |
| | incorporation of distance sampling and a quantitative characterization of habitat at point count |
| | locations. During spring migration, we estimated the most common species accounted for a |
| | population that ranged between 6,500 and 12,000 birds within Vicksburg National Military Park. |
| | Species with average populations of >500 individuals during migration were: Blue-gray |
| | Gnatcatcher (Polioptila caerulea), Cedar Waxwing (Bombycilla cedrorum), White-eyed Vireo |
| | (Vireo griseus), Indigo Bunting (Passerina cyanea), Summer Tanager (Piranga rubra), |
| | Tennessee Warbler (Vermivora peregrina), and Hooded Warbler (Wilsonia citrina). We |
| | estimated >3,800 pairs of 56 bird species breed in Vicksburg National Military Park. The five |
| | most abundant breeding species, Blue-gray Gnatcatcher, White-eyed Vireo, Summer Tanager, |
| | Indigo Bunting, and Northern Cardinal (Cardinalis cardinalis) accounted for >2,600 pairs. |
| | Friday, September 22, 2006 |