Landscape-Abundance Relationships of Male Eastern Wild Turkeys Meleagris gallopavo silvestris in Mississippi, USA

Abstract

The effects of landscape alteration on wildlife have drawn increasing attention from ecologists as landscapes have rapidly changed worldwide. Large-bodied birds are highly sensitive to habitat loss and fragmentation. We aimed to test two hypotheses concerning landscape-abundance relationships of male Wild Turkeys Meleagris gallopavo silvestris, the largest galliform in North America. The landscape fragmentation hypothesis posits that animal populations would decline linearly with habitat fragmentation, independent of the effects of habitat loss. The landscape composition hypothesis states habitat quantity, measured at spatial scales larger than the individual territory, would influence species abundance. Using the National Land Cover Database, we extracted the metrics of landscape fragmentation and composition at turkey annual dispersal (i.e., a buffer of 16-km radius) and annual home range (i.e., a buffer of 2.15-km radius) scales, respectively, for 28 wildlife management areas across Mississippi, USA. We used the mean annual number of harvested adult males per hunter day during annual spring hunting seasons (mid-March to mid-April) from 2001 to 2005 as a relative abundance index. Male Wild Turkey relative abundance increased with increasing fragmentation of hardwood forest (i.e., deciduous trees as the dominant form of vegetation) at both annual home range and dispersal scales, contrary to the prediction of the landscape fragmentation hypothesis. Male Wild Turkey abundance also increased with increasing landscape interspersion and juxtaposition index (i.e., an index of landscape spatial configuration) at the annual dispersal scale. We found nonlinear relationships between the proportion of hardwood forest and male turkey abundance, supporting the landscape composition hypothesis. Male turkey relative abundance peaked at 29% hardwood forest within the annual dispersal distance. Diverse landscapes are beneficial to Wild Turkeys at large spatial scales.