Short-term responses of Timber Rattlesnakes (Crotalus horridus) to even-aged timber harvests in Indiana

by

Brian J. MacGowan, Andrea F.T. Currylow, and Jami E. MacNeil

BJM, AFTC, JEM: Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN 47907-1159, USA; and AFTC Current: Integrative and Evolutionary Biology, University of Southern California, Los Angeles, CA 90089, USA

Abstract – The Timber Rattlesnake (Crotalus horridus) is a species of conservation concern throughout much of the Midwest and is endangered in Indiana. While the habitat preferences of Timber Rattlesnakes have been studied throughout much of its range, little empirical data is available on the effects of forest management on this species. During 2007-11, we monitored movement of 47 adult Timber Rattlesnakes using radio telemetry in southcentral Indiana. Snakes were tracked during one or more seasons (April-October) for two years prior to, and three years following scheduled timber harvests (4-ha clearcuts and 4-ac understory removal as the first stage of shelterwood harvests). Annual home range estimates (100% MCP) averaged 42.2 ha for both sexes combined (range 1.6 ha to 271.3 ha). The average home range for males (68.8 ha) was larger (P<0.001) than either non-gravid females (22.7 ha) or gravid females (11.7 ha). While some spatial shifts were observed for some snakes after harvest, we observed no effects on seasonal behavior. Mean home range size using MCP or Kernel Density Estimates did not vary (P>0.05) pre- or post-harvest in control sites or treatment sites for either sex. Canopy and understory removal on a small scale (~4 ha) in a relatively forested landscape did not affect the movements of adult timber rattlesnakes 1-3 years post-harvest. Our results suggest that this scale and size of timber harvests are compatible with Timber Rattlesnakes.