Nest survival of wild turkeys Meleagris gallopavo silvestris in a mixed-use landscape: influences at nest-site and patch scales

Nest survival is a critical factor affecting avian demographics, and can be influenced by nesting chronology, fine scale nes-tsite selection and broad-scale landscape characteristics. We modeled the relative influences of nest age, temporal variation in nest success and habitat-related covariates at two spatial scales (nest-site and patch scale) on daily nest survival during incubation for eastern wild turkeys Meleagris gallopavo silvestris in a mixed-use landscape. Daily survival rate of turkey nests during incubation increased as percent understory cover (vegetation < 1 m tall) increased and decreased with increasing density of woody shrubs and saplings and herbaceous stems < 1 m tall (understory vegetation density) around the nest. We suggest that nest survival may be dependent on a balance of sufficient understory cover around nests to provide concealment for hens and nests, but with understory vegetation density below levels that reduce the hen's ability to detect a predator or to escape after detecting a potential threat. The balance between sufficient understory cover and limited density of understory vegetation occurred where understory (< 1 m tall) cover exceeded 50% and understory vegetation density was < 25 stems/m(2). Models that included variables related to the patch scale (e.g. fragmentation, edge and dominant land-cover class in a patch) did not receive strong support, demonstrating the relative importance of finer scale nest-site variables over patch-scale variables in determining survival of wild turkey nests in our highly variable mixed-use landscape.