EFFECTS OF RESIDENTIAL DEVELOPMENT ON FOREST DWELLING NEOTROPICAL MIGRANT SONGBIRDS

Many bird species are in local or regional decline because of habitat loss or degradation. We attempted to disentangle the effects of reside ntial development from the effects of forest sire on forest-bird commu nities, with particular emphasis on Neotropical migrant species. Two v ariables were examined for their influence on avian diversity and abun dance: forest size and the number of houses outside a forest within 10 0 m of the edge. We found that Neotropical migrants consistently incre ased in number and abundance as forest size increased. Of greater inte rest, we found that the number of houses surrounding a forest severely undermined its suitability for Neotropical migrants. Neotropical migr ants consistently decreased in diversity and abundance as the level of adjacent development increased regardless of forest size. The effects of development were striking: 4-ha woodlots without any nearby houses had on average a richer, more abundant Neotropical community than did 25-ha urban woodlots. No predictable pattern of change concerning dev elopment or forest size was observed for short-distance migrants or pe rmanent residents. Current planning regulations generally permit housi ng right up to forest edges. This practice may prevent protection of e cological features within the forest. Threshold distances for housing developments around forests need to be determined to prevent or minimi ze adverse effects on features and functions within the forests.