Allegheny woodrat and eastern small-footed bat inventory: White Rocks ? Cumberland Gap National Historical Park

Abstract

Surveys were conducted for the presence of Allegheny woodrats, eastern small-footed bats, and their habitat within Sample Units surrounding potential climbing routes on the White Rocks cliff of Cumberland Gap National Historical Park. White Rocks is a 200-300ft south facing cliff along the Virginia- Kentucky border that contains the typical habitat requirements of both species: rock ledges, outcrops, or a network of fissures and crevices surrounded by forested habitat. The eastern small-footed bat uses this type of habitat primarily during the summer months for roosting while the Allegheny woodrat is present year-round building nests within deep crevices. The eastern small-footed bat is listed as threatened in Kentucky and both are considered Species of Greatest Conservation Need in Virginia. The rock-climbing community has approached the National Park Service with interest in opening the cliff to recreational climbing. The results of this survey will be used to assess impacts to the species and aid in the studies required for the potential development of a formal climbing management plan. Surveys were conducted from August 24 to September 3, 2021, and included searches of the cliff face via rappelling, ground searches of suitable habitat surrounding the rim and base of the climbing routes, and noninvasive woodrat camera trap and bat acoustic surveys. Suitable eastern small-footed bat and Allegheny woodrat habitat was documented along all eleven potential climbing routes, and results of the acoustic and camera trap surveys confirmed the presence of both species. Surveyors did not observe roosting bats during visual encounter surveys, so we cannot confirm they are roosting along the specific climbing routes. It is likely they are using or could use the habitat at some point given their presence at the site. Surveyors did not observe obvious sign of woodrat presence, perhaps due to the complexity of the cliff habitat, but woodrats were captured at 32 of 37 (86%) camera sites. Video of woodrat activity at sites F3-C3, MF-C3, and CC-C1 confirm that these cameras were placed at crevices actively used by woodrats for caching food. Woodrat activity was captured on the first night at nearly half of the camera sites (40%) and within all Sample Units except SU-4. This suggests that the rim and/or base of most climbing routes are at or near core activity centers. Detection data was fitted to occupancy models to estimate probabilities of site occupancy and detection. Consistent with observations of woodrat activity detection probabilities and na?ve estimates of occupancy indicate woodrats are active at both the rim and base throughout the white rocks area. Design constraints, however, make it difficult to make strong inferences about factors affecting occupancy at the site or to predict occupancy at unsampled areas of the White Rocks cliff. Detection probabilities were high in all Sample Units especially after the first night of detection and were positively associated with habitat. However, these variables had little to do with site occupancy rates and are not very informative for predicting the influence of climbing activities on Allegheny woodrats. Research on the effects of rock climbing to roosting bats and Allegheny woodrats is lacking, but it has the potential to negatively impact these species both directly and indirectly. Directly through disturbance or harm to roosting bats or woodrats during climbing activities and indirectly through degradation of the cliff face and loss of suitable habitat. Whether climbing activities negatively affect the population of either species may depend on the amount of suitable habitat in areas where climbing does not occur and the extent of climbing activities. Suitable habitat does not appear to be a limiting factor at the site and the White Rocks cliff area extends beyond the potential climbing areas. These and other factors such as the presence of other species of concern should be considered when evaluating alternatives to continue climbing closures or consider opening the cliff to recreational climbing with protection measures. Measures that may reduce the impact of climbing activities on these species include additional surveys to determine exact roosting or nesting areas, restrictions on the amount and timing of climbing activities, restrictions on actions that degrade or remove vegetation from the rock surface, and education about the presence of these species at the site.