Effects of landscape structure on male density and spacing patterns in wild turkeys (meleagris gallopavo) depend on winter severity

Abstract

The influence of landscape structure on abundance or spacing patterns of generalist bird species may be nonlinear and vary annually depending on the severity of environmental conditions. The Eastern Wild Turkey (Meleagris gallopavo sylvestris) is a generalist forest species that experiences high mortality when snow reduces food availability. Although increasing amounts of cornfield habitat may benefit Wild Turkeys by providing an alternate food source, reduced forest cover or elevated levels of forest fragmentation associated with increased corn (Zea mays) production could be detrimental. We evaluated the hypothesis that spring density of male Wild Turkeys increases with the amount of corn habitat as long as forest cover remains a dominant landscape component and that this increase is more prominent following a winter with thick snow accumulations. We performed point counts and corrected for imperfect detection in 2003 and 2004 at 130 randomly distributed sites in southern Québec. After a mild winter, male density peaked in landscapes characterized by 25-50% forest cover and a large amount of edge between forest and open habitats. After a harsh winter, male density decreased with annual crop cover when forests represented <20% of the landscape and increased when they represented >40%. Male aggregation was higher and increased with male density at a slower rate than if individuals had been randomly distributed, yet landscape structure had only a marginal effect on aggregation. Our results suggest that Wild Turkeys' response to landscape structure depends on environmental conditions and that this generalist forest species benefits from cornfields where forest cover is fragmented but abundant. © The American Ornithologists' Union, 2009.