U.S. Geological Survey Home Page USGS Patuxent Wildlife Research Center Science Meetings; dedicated to Chandler S. Robbins USGS Patuxent Wildlife Research Center; Science Meetings dedicated to Chandler S. Robbins Dedicated to Chan Robbins USGS Patuxent Wildlife Research Center; Science Meetings dedicated to Chandler S. Robbins Poster Abstracts from USGS Patuxent Wildlife Research Science Meetings, October, 2006
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



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