To evaluate factors influencing a suburban bird community in coastal northern California, we examined the abundance, richness, and diversity of wintering birds at 75 locations within the city of Arcata. For each location we used aerial imagery to determine the proportions of vegetation and impervious surfaces within 75 m and the distances to various landscape features. Human activity was measured and used as a covariate in model selection. Total bird abundance, species richness, and diversity declined with the proportion of road surface at a site, while the abundance of non-native species increased with the cover of roads and structures. The proportions of shrub and tree cover at a site predicted total abundance and richness positively. The effect of trees on species diversity was increasingly positive in more urban areas. Several species, such as Steller's Jay (Cyanocitta stelleri), Ruby-crowned Kinglet (Regulus calendula), Wrentit (Chamaea fasciata), Winter Wren (Troglodytes troglodytes), Yellow-rumped Warbler (Dendroica coronata), and Red-breasted Nuthatch (Sitta canadensis), were positively associated with tall vegetation and negatively associated with road and structure cover. The White-tailed Kite (Elanus leucurus) was positively correlated with grass and trees and negatively correlated with road and structure cover. These species may be the most vulnerable to the habitat changes associated with urbanization in this study area. We recommend maintaining/restoring native shrubs and or trees to enhance bird communities in developed areas or to improve planning where development is inevitable. Increasing shrub and tree cover may be especially valuable in newer neighborhoods and far from forest edges.
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1 May 2010
Influence of Suburban Habitat on a Wintering Bird Community in Coastal Northern California
Ryan S. Kalinowski,
Matthew D. Johnson
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The Condor
Vol. 112 • No. 2
May 2010
Vol. 112 • No. 2
May 2010