COMPARING THE EFFECTS OF LANDSCAPE FRAGMENTATION BY FORESTRY AND AGRICULTURE ON PREDATION OF ARTIFICIAL NESTS

Fragmentation of forested landscapes can reduce the reproductive succe ss of birds occupying residual forest patches. Previous studies,howeve r, have focused primarily on how nest predation can change when landsc apes become fragmented by agriculture rather than by logging. To deter mine if predation on artificial nests in forest patches was influenced by the surrounding landscape, we placed ground and shrub ness along t he edge and interior of forest patches located in agricultural, logged ,and contiguous forest landscapes within a single region of the southe rn boreal mixedwood forest of central Canada. Nest predators were iden tified using remotely triggered cameras and by marks left in plasticin e eggs, whereas the relative abundance of nest predators such as corvi ds and small mammals was estimated by surveys and live-trapping. The p ercentage of ground nests destroyed at the edge and interior of patche s in the logged and contiguous forest landscapes was significantly low er than the edge or interior of patches in the agricultural landscape. No differences in predation rate were observed for shrub nests among landscapes. We attributed higher rates of predation in the agricultura l landscape to higher densities of red squirrels (Tamiasciurus hudsoni cus) in the interior and a greater diversity of predators along edges. The similarity in predation rate between logged and contiguous forest landscape suggest that fragmentation caused by logging may result in little change in predator communities and in this respect, might be si milar to fragmentation caused by natural disturbance regimes such as f ire. In contrast, fragmentation by agriculture seems to have more seri ous consequences for nesting birds. Policy changes that limit the grow th of agriculture in the southern boreal mixedwood forest are required to conserve the diverse avifauna of this region.