Reduced predation of artificial nests in border-edge cuts on woodlots

Forest fragmentation has resulted in abrupt, artificial edges that may not provide transitional shrub habitat needed by edge- and shrub-nesting specie s. The creation of border-edge cuts (shrub transitional zones 15-40 m wide) at woodlot edges increases horizontal and vertical understory cover, and m ay affect habitat suitability for edge nesting species. Using artificial ne sts, wr tested the hypothesis that predation rates in border-edge cuts were lower than in uncut edges. During May-June 1997, we placed 10 artificial n ests: containing 2 northern bobwhite (Colinus virginianus) eggs in each edg e. Nests: were monitored fur depredation for 14 days. Most nest predation w as attributed to avian predators. snakes. and small mammals. with a few nes ts depredated by large mammals. Mean pre dation rates were more than twice as high in uncut edges (88 +/- 7%; (x) over bar +/- SE) as in border-edge c uts (36 +/- 11%). Vegetation cover from 0 to 2 m at the nest site was great er at nests: in bolder-edge cuts (85.6 +/- 4.1%) than in uncut edges (59.5 =/- 3.3%). Predation rates within edges were negatively correlated with mea n cover from 0 to 2 m at the nest site (r = -0.90) and mean cover at nest h eight (r=-0.86), However, predation rates on natural nests found the previo us year in both edge types did not follow the same trend, indicating that f urther research is needed on both the differences in individual bird specie s' productivity and predator communities between the 2 edge types.