Microhabitats of Merriam's Turkeys in the Black Hills, South Dakota

Abstract

Merriam's Turkeys (Meleagris gallopavo merriami) are associated with ponderosa pine (Pinus ponderosa) forests in the western United States, but are not native to the ponderosa pine forest of the Black Hills, South Dakota. The Black Hills population was established by transplanting birds from New Mexico and Colorado between 1948 and 1951. Despite being outside its original range, this population provides a unique opportunity to assess mechanisms of habitat selection because the age of the population is known and literature indicates that it is more productive than other populations. We studied microhabitats of Merriam's Turkeys in the Black Hills, South Dakota between 1986 and 1991. We found few differences in microhabitats among diurnal time periods or between sexes. Cluster analysis of variables at turkey microhabitats indicated two groups, broadly interpreted as summer and winter microhabitats. Winter microhabitats of turkeys had less understory vegetation and more overstory cover than random sites, which in turn had less understory and more overstory cover than summer microhabitats. Both random sites and winter microhabitats had higher basal area of ponderosa pine than summer microhabitats. Summer microhabitats had trees with the largest dbh. Random sites had more small and large woody debris than sites used by turkeys. Tree density at random sites was more than two times greater than at winter microhabitats and more than three times greater than at summer microhabitats. Turkeys preferred southern exposures during winter. Production of pine seed, a major food item of turkeys, differed among years. There was a strong relationship between abundance of pine seeds and microhabitats selected by turkeys. Basal area of microhabitats between October and March was positively correlated with annual ponderosa pine seed production. Abundance of ponderosa pine seeds at turkey microhabitats during this period was at least four times the estimated average annual production. Management prescriptions for ponderosa pine of basal area ≤ 18 m2/ha will reduce winter habitat for turkeys. Summer habitats are more compatible with timber management goals for ponderosa pine in the Black Hills.