Effects of black bear relocation on elk calf recruitment at Great Smoky Mountains National Park

Abstract

Previous research from 2001 to 2006 on an experimentally released elk (Cervus elaphus) population at Great Smoky Mountains National Park (GSMNP or Park) indicated that calf recruitment (i.e., calves reaching 1 yr of age per adult female elk) was low (0.306, total SE = 0.090) resulting in low or negative population growth (λ = 0.996, 95% CI = 0.945–1.047). Black bear (Ursus americanus) predation was the primary calf mortality factor. From 2006 to 2008, we trapped and relocated 49 bears (30 of which were radiocollared) from the primary calving areas in the Park and radiomonitored 67 (28 M:39 F) adult elk and 42 calves to compare vital rates and population growth with the earlier study. A model with annual calf recruitment rate correlating with the number of bears relocated each year was supported (ΔAICc = 0.000; β = 0.070, 95% CI = 0.028–0.112) and a model with annual calf recruitment differing from before to during bear relocation revealed an increase to 0.544 (total SE = 0.098; β = −1.092, 95% CI = −1.180 to −0.375). Using vital rates and estimates of process standard errors observed during our study, 25‐yr simulations maintained a mean positive growth rate in 100% of the stochastic trials with λ averaging 1.118 (95% CI = 1.096–1.140), an increase compared with rates before bear relocation. A life table response experiment revealed that increases in population growth were mostly (67.1%) due to changes in calf recruitment. We speculate that behavioral adaptation of the elk since release also contributed to the observed increases in recruitment and population growth. Our results suggest that managers interested in elk reintroduction within bear range should consider bear relocation as a temporary means of increasing calf recruitment. © 2011 The Wildlife Society.

A review of vital rates and cause‐specific mortality of elk Cervus elaphus populations in eastern North America

“…, l = process variance for estimate reported in Yarkovitch et al. , m = mean not weighted by sample size because sample size not reported for some studies, n = vital rate not included in weighted mean calculation.…”

Mammals of Great Smoky Mountains National Park: 2016 Revision

“…Predation: The Wapiti that were originally released into the Park had never dealt with American Black Bears as predators and, as a result, during the early years of the Wapiti reintroduction, calf survival was low (Yarkovich 2009). Black Bears were relocated during calving season as a method to reduce predation on the Wapiti calves (Yarkovich 2009).…”

“…Black Bears were relocated during calving season as a method to reduce predation on the Wapiti calves (Yarkovich 2009). Survival rates for calves has increased over the years (Yarkovich 2009), so it seems that over time, the Wapiti have learned to deal with bears and to hide and defend their newborns against them. Coyotes also prey on Wapiti calves (Yarkovich 2009).…”

The late-denning activities of the American black bear in Utah

“…Ozoga and Verme (1982) concluded that a significant loss of fawns to black bears may be possible, although their study was limited to an enclosure. Researchers have also found evidence that black bears may negatively affect recruitment of calves in a reintroduced population of elk in the eastern U.S. (Yarkovich et al 2011), but research has also suggested that predation appears to have a larger affect at lower ungulate densities (Zagar and Beechum 2006). In Idaho, elk calf survival seemed to be influenced by birth weight, habitat structure, and black bear and cougar harvest (presumably in relation to their respective densities); calf mortality through predation by black bears was described as additive (i.e., in addition to, rather than replacing, other sources), and the authors suggested that a spring bear season may be effective for improving calf survival (White et al 2010).…”