Breeding Bird Relationships to Landscape Metrics in Coastal Plain Georgia

Some avian species in the southeastern United States are declining, and population decreases may arise from changes in vegetation type area or structural condition. Our objective was to compare abundance of conservation priority bird species with landscape variables. We found, even in the highly forested Coastal Plain of Georgia, that areal extent and core area of cover types were related to abundance for certain bird species. Acadian flycatcher and field sparrow had models that incorporated positive area variables. Downy woodpecker, northern parula, orchard oriole, prairie warbler, and summer tanager had models that included positive area and edge associations with varying scales and vegetation types. Edge appeared in models for red-bellied woodpecker, blue jay, and brown-headed cowbird. More than half of all species did not have models that met prediction thresholds. Systematic assessment of area requirements for declining species provides information for management, conservation, and research.

Are temperate mixedwood forests perceived by birds as a distinct forest type?

Forestry practices used in mixedwood forests have led to a reduction of the availability of mixedwood stands and to a simplification of the forest mosaic, with unknown consequences on wildlife. We assessed bird occurrences at different spatial scales (50-, 100-, and 1000-m radius) in response to coniferous, deciduous, and mixedwood stands within the Quebec balsam fir – yellow birch domain. Our objective was to evaluate whether birds perceive temperate mixedwood forests as distinct from deciduous and coniferous forests. We quantified bird occurrence at 57 observation points and determined habitat composition from forest maps. At the 50-, 100-, and 1000-m scales, the occurrence of two, four, and four species, respectively, was positively related to mixedwood stands. Among them the Blackburnian Warbler, the Northern Parula, the Black-throated Blue Warbler, and the Ovenbird responded at more than one scale. Some species were also influenced by coniferous and deciduous stands at the three spatial scales. Mixedwood stands were positively associated with the occurrence of many species and moreover were preferred over coniferous or deciduous stands by some species. These results support our hypothesis that mixedwood forests are distinct habitats and provide a new justification for preserving this forest type.