Comparison of Microhabitat Conditions at Nest Sites Between Eastern (Meleagris gallopavo silvestris) and Rio Grande Wild Turkeys (M. g. intermedia) in Northeastern South Dakota

Abstract

Rio Grande wild turkeys (Meleagris gallopavo intermedia) were trapped in Oklahoma and released in northeastern South Dakota during the early 1970s. Based on wintering counts, this population peaked at over 1000 birds in the mid 1980s, but steadily declined to <200 in 1996. This decline prompted the introduction of eastern wild turkeys (M. g. silvestris), which were indigenous to southeastern South Dakota, as a replacement subspecies. We compared nest site characteristics of translocated eastern wild turkeys with those of established Rio Grande wild turkeys. Over a 2 y period we radio-marked 23 eastern females, and 21 Rio Grande females. Eastern females initiated 45 nests, whereas Rio Grande females initiated 41 nests. Vegetation type selection for nest sites (e.g., woodland, grassland and shrub) did not differ between Rio Grande and eastern wild turkeys (P = 0.96). However, turkey nest sites (subspecies pooled) differed from paired reference sites by having: (1) more nest sites directly under shrubs (P < 0.001) within woodlands and shrublands, (2) more trees within 1 m of the nest bowl (P = 0.001) in woodlands and (3) greater cover above the nest bowl (P = 0.007) within grasslands and shrublands. Frequency of vegetation types selected by female wild turkeys of both subspecies as nest sites differed (P = 0.001) from the frequency of vegetation types randomly sampled. Although shrub vegetation types were least available, females selected shrub vegetation types (primarily western snowberry [Symphoricarpos occidentalis]) for the majority (53%) of nest initiations. Other nests were divided between woodlands (27%) and grasslands (20%). Nest success was not correlated with vegetation type.