Flying squirrel distribution and habitat use at Mount Rushmore National Memorial

Licht, Daniel; Baubac, Christi; Swelund, Jane

We trapped flying squirrels at Mount Rushmore National Memorial. We captured more flying squirrels in areas that were not thinned and cleared of down woody debris. Mount Rushmore National Memorial (NMEM) is an iconic unit of the National Park Service because of the granite carving of four U.S. presidents. The carved mountain sits within a scenic ponderosa pine (Pinus ponderosa) forest that is ecologically valuable. In 2010-11 a small mammal study was conducted to better understand the small mammal distribution and abundance within the park and the impacts of the forest thinning and fuel reduction on those species. One component of the study consisted of live-trapping northern flying squirrels (Glaucomys sabrinus). The objectives were to: 1) document the presence of flying squirrels within the park, 2) learn about the distribution and habitat use by flying squirrels, and, 3) better understand the impacts of forest thinning and fuel reduction to flying squirrels. To better interpret the live-trapping results motion-activated cameras were incorporated into the study. Sixty-nine trap stations were established in the park; all in drainages as such sites were deemed most likely to support flying squirrels. The stations were categorized as being in forest stands that were un-thinned, partially thinned, or thinned. The un-thinned sites had no evidence of recent tree cutting or removal of downed woody material. The partially thinned habitat was along a power-line right-of-way where a limited amount of thinning occurred. The thinned sites were in forest stands that had recently had all trees less than 25 cm dbh removed as well as most downed woody material. The cut trees and woody material was chipped and spread across the forest floor. There were 25 flying squirrel captures, some of which may have been recaptures, in 608.5 effective trap nights. Based on the capture rate of 4.1 animals per 100 effective trap-nights it appears that the park had a healthy flying squirrel population in 2010-11. Flying squirrels were captured in the Starling Basin, Grizzly Creek, and Lafferty Gulch drainages as well as the unnamed drainage that parallels a powerline near the junction of Highways 244 and 16. Flying squirrel capture-rates were 10.2 animals per 100 effective trap-nights in the un-thinned stands, 3.6 in the partially-thinned stands, and 0.4 in the thinned stands. Incidental captures (least chipmunks [Tamias minimus], red-backed voles [Clethrionomys gapperi], and deer mice [Peromyscus maniculatus]) ranged from 17.7 per 100 effective trap-nights in the un-thinned stands to 4.3 in the partially thinned and 0.4 in the thinned stands. The motion-activated cameras detected 21.3 squirrels per 100 camera nights. During nights when both traps and cameras were operating at the same station the traps captured 2.4 squirrels per 100 effective trap-nights and the cameras detected 16.7 squirrels per 100 nights. The cameras documented several instances of a squirrel partially in a trap, yet a capture did not occur. Depending on the objectives, motion-activated cameras may be a more effective way to document flying squirrel presence and distribution.

Flying squirrel distribution and habitat use at Mount Rushmore National Memorial

Series

See also