Date of Award
Master of Science
Wildlife and Fisheries Science
Joseph D. Clark
David A. Beuhler, David A. Etnier, Micheal R. Pelton
Black bears (Ursus americanus) have been extirpated from the Big South Fork Area (BSFA) of Kentucky and Tennessee since the turn of the 20th century. Although this area is within the bear's historic range, it may be unreachable to individual bears through natural dispersal. Wildlife managers and the public were interested in reestablishing a population of black bears to BSF A. A habitat analysis found that the area could support bears. However, managers remained concerned about how humans would interact with bears; furthermore, managers needed to know how to overcome the homing ability of translocated bears.
I tested 2 translocation techniques designed to limit the homing ability of bears. Both techniques were based on the concept of a soft release, involving a short period of acclimation prior to release. The first was a winter-release technique, involving the translocation of pre- or post-parturient bears from their dens and placing them in dens within the release area. The second, a summer-release technique, involved translocating bears to the release area during the summer and holding the bears in pens for a 2-week acclimation period.
I translocated a total of 14 bears from the Great Smoky Mountains National Park to BSF A, a distance of approximately 160 km. I translocated 8 bears with the winter-release technique and 6 bears with the summer-release technique.
I compared post-release movements between the 2 release techniques for the first 2 weeks post-release with the Wilcoxon signed-rank test. No difference in total movement (Z = 1.357, P = 0.1747) or net movement (Z = 1.214, P = 0.100) was found between winter- and summer-released bears. However, because of rapid movements outside BSF A, complete movement data for 2 summer-released bears were not available. Therefore, I substituted the mean total and net movements of summer-released bears for these 2 bears during the interim when their signals were lost. The total movement of winter-released bears was less (Z = 2.227, P = 0.013) than summer-released bears for the first 2 weeks post-release. Also, the net movement of winter-released bears was less (Z = 2.217, P = 0.013) than summer-released bears for the first 2 weeks post-release. The average daily movement of winter-released bears was less (Z = 2.214, P = 0.027) than summer-released bears during the first 2 weeks post-release. Circuity was less (Z = 2.074, P = 0.038) for winter-released bears than for summer-released bears during the first 2 weeks post-release.
I determined site fidelity for 7 winter-released bears and 6 summer-released bears with the site fidelity test from the MOVEMENT module (Hooge et al. 1999) of Arc View (Environmental Research Institute, Inc. Redlands, Ca.). Within 1 year post-release, movements were too constrained to be random for all winter-released bears. One year after release, movements were too constrained to be random for 3 of the 6 summer-released bears; 1 summer-released bear continued to show random movements 1 year after release; the 2 remaining summer-released bears could not be evaluated at 1 year post-release because of mortality or homing.
I applied the multi-response permutation procedure to the post-release movements of translocated bears that established themselves in BSF A, regardless of release technique, to determine if movements became more concentrated as bears adjusted to the release area. The movements of 6 of 8 bears became more concentrated within 6 months; the movements of the remaining 2 bears became more concentrated within 9 months. This could indicate that translocated bears are establishing home ranges within the release area.
estimated adult survival for translocated bears using the Kaplan-Meier staggered entry procedure. I compared annual survival between winter- and summer-release techniques. Survival of winter-released bears (0.875) was greater (Z = 3.084, P = 0.001) than summer-released bears (0.200). Vehicle collisions accounted for 3 of the 6 mortalities of summer-released bears.
Den visits were performed in the winters of 1997, 1998, and 1999. Researchers visited the dens of the 2 remaining radio-collared bears in BSFA and confirmed natural reproduction had occurred. This could mean that the translocation of adult males to BSFA is unnecessary.
Interactions between humans and bears were documented by National Park Service personnel. Fifty-three sightings occurred between April 1996 and November 1999; no incidences of nuisance behavior by translocated bears was documented.
I used a population model developed for polar bears (U. maritimus; Taylor et al. 1987a, 1987b) and adapted for black bears to estimate population growth and probability of extinction of translocated bears. I modeled population growth under various stocking scenarios to determine the most timely and efficient way to reestablish bears to BSFA. If no more bears are translocated to BSFA, the data indicates the population will become extinct. The population model suggests that at least 1 additional stocking of 6 adult females with 12 cubs will be needed to sustain the population. The addition of 6 adult females with 12 cubs each year for 4-6 years will yield the most timely results.
I used compositional analysis (Aebischer et al. 1993) to compare habitat use of translocated bears to that predicted by the Habitat Suitability Index (HSI) values determined by van Manen (1990). Bears did not use the habitat at BSFA as determined by the HSI values; however, placement of release sites, improved habitat quality, and roads could have influenced this result.
The winter-release technique demonstrated clear advantages over the summer-release technique in terms of limiting post-release movements and increasing survival of translocated bears. The winter-release technique could be useful anytime managers need to establish or augment black bear populations.
Eastridge, Rick, "Experimental Repatriation of Black Bears to the Big South Fork Area of Kentucky and Tennessee. " Master's Thesis, University of Tennessee, 2000.