A Meta‐Analysis of Forest Cover, Edge Effects, and Artificial Nest Predation Rates

Abstract

Landscape fragmentation has been among the most intensely studied topics in conservation biology for decades (Gates & Gysel 1978; Murcia 1995). The influence of habitat edge has often been investigated as an important feature in fragmented areas, especially with respect to bird nesting success, as evidenced by three recent reviews. Paton (1994) concluded that current evidence, although equivocal, suggests that predation and parasitism rates are often significantly greater within 50 m of an edge. Andren (1995) examined edge (or patch size) effects in a review of 40 papers and concluded that edge-related increase in predation seems to be most commonly found inside forests surrounded by farmland and was rarely found in forest mosaics. Major and Kendal (1996) showed that a preponderance of studies demonstrated a positive correlation between predation rate and the degree of habitat fragmentation, but found more variable results regarding edge effects. We believe that none of these papers adequately addressed the issue of whether or not predation rates and edge effects differ between deforested versus forested landscapes. Thus, we decided to evaluate relationships between degree of forest cover in a landscape and (1) avian nest success rates and (2) the existence of elevated predation rates near habitat edges. We combined data from 13 previous studies in 33 U.S. landscapes to explore patterns of nest predation and landscape composition.