A Multi-Scale Perspective of the Effects of Forest Fragmentation on Birds in Eastern Forests
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In: George, T. Luke; Dobkin, David S., eds. Effects of Habitat Fragmentation on Birds in Western Landscapes: Contrasts With Paradigms from the Eastern United States. Studies in Avian Biology. 25:8-19
We propose a model that considers forest fragmentation within a spatial hierarchy that includes regional or biogeographic effects, landscape-level fragmentation effects, and local habitat effects. We hypothesize that effects operate "top down" in that larger scale effects provide constraints or context for smaller scale effects. Bird species' abundance and productivity vary at a biogeographic scale, as do the abundances of predators, Brown-headed Cowbirds (Molothrus ater), and land-use patterns. At the landscape scale the level of forest fragmentation affects avian productivity through its effect on predator and cowbird numbers. At a local scale, patch size, amount of edge, and the effects of forest management on vegetation structure affect the abundance of breeding birds as well as the distribution of predators and Brown-headed Cowbirds in the landscape. These local factors, along with nest-site characteristics, may affect nest success and be important factors when unconstrained by processes at larger spatial scales. Landscape and regional source-sink models offer a way to test various effects at multiple scales on population trends. Our model is largely a hypothesis based on retroduction from existing studies; nevertheless, we believe it has important conservation and research implications.
KeywordsBrown-headed Cowbirds eastern forests edge-effects fragmentation landscape Molothrus ater multi-scale nest predation predators songbirds
Thompson, Frank R.; Donovan, Therese M.; DeGraff, Richard M.; Faaborg, John; Robinson, Scott K. 2002. A Multi-Scale Perspective of the Effects of Forest Fragmentation on Birds in Eastern Forests. In: George, T. Luke; Dobkin, David S., eds. Effects of Habitat Fragmentation on Birds in Western Landscapes: Contrasts With Paradigms from the Eastern United States. Studies in Avian Biology. 25:8-19