Longevity and reuse of black bear dens in managed forests of coastal British Columbia

Davis, Helen; Hamilton, Anthony N.; Harestad, Alton S.; Weir, Richard D.

doi:10.1002/jwmg.253

Cited by 7 publications

(14 citation statements)

References 13 publications

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“…Although it is clear bears selected large woody structures as dens in this study, it is not clear how limitations on the availability of these structures might affect their demographics, and perhaps other factors are more influential on black bear abundance. The strong selection for large woody structures where they are available, such as Southeast Alaska and the coastal Pacific Northwest (Bull et al 2000, Davis et al 2012, Immel et al 2013), is circumstantial evidence of their importance to bears. Denning behavior in black bears has evolved to conserve metabolic resources during cold winters when food is scarce (Hellgren 1998).…”

Section: Discussionmentioning

confidence: 99%

“…American black bears ( Ursus americanus ) may den in particularly large live and dead trees (Bull et al 2000, Davis et al 2012). Suitable den and resting sites provided by live and dead trees may be important for the survival of bears (Johnson and Pelton 1981, Linnell et al 2000).…”

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confidence: 99%

“…Suitable den and resting sites provided by live and dead trees may be important for the survival of bears (Johnson and Pelton 1981, Linnell et al 2000). In moist environments, dens excavated in soil may flood, resulting in cub mortality (Alt 1984), and in higher‐latitude forests, adequate denning trees may afford bears thermal protection (Davis et al 2012). Denning is prolonged in higher latitudes in response to cold temperatures and limited food resources (Smith et al 1994), which indicates the potential value of adequate dens to bear condition and survival in these climes.…”

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confidence: 99%

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Black Bears Select Large Woody Structures for Dens in Southeast Alaska

et al. 2021

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Timber interests target coastal temperate rainforests, and within them stands composed of large trees potentially selected by American black bears (Ursus americanus) for denning. We identified the location of 75 black bear dens (used ≥14 days) in an intensively logged area on Prince of Wales Island, Alaska, USA. We ground‐visited a subset (n = 43) of these sites to measure the diameter of living trees and woody structures used by black bears for denning. We contrasted dens with random trees available in the study area in a series of models to characterize black bear den selection. All but 1 of 43 ground‐visited dens were located within woody structures, and all but 2 of these structures were >1 m diameter at breast height (dbh). We built resource selection functions (RSFs) to investigate black bear den selection across a range of spatial scales, though estimated selection was generally scale invariant. Black bears strongly selected large‐diameter woody structures (dead or alive) as dens at the home‐range scale, with the estimated relative strength of selection (RSS) for a 2‐m‐diameter tree approximately 166 times that of a 1‐m‐diameter tree. The estimated RSS of logged forest was unexpectedly greater (2.75 times) than that of the remaining commercially valuable old‐growth forest. Selection for den structures within stumps in previously logged stands suggests features of the woody structure may be of greater importance to black bears selecting dens than attributes of the surrounding forest. There was no observed correlation between bear den selection and second‐growth age, indicating that stumps may persist as suitable dens well after logging. Because denning is an important part of their life history and the denning structures used by black bears on Prince of Wales Island will eventually decay, retaining habitat value for bears in areas intensively managed for timber harvest requires strategies to recruit very large, old trees throughout the landscape. © 2021 The Wildlife Society.

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Section: Discussionmentioning

confidence: 99%

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Black Bears Select Large Woody Structures for Dens in Southeast Alaska

et al. 2021

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“…In particular, the availability of hard mast (i.e., beechnuts, acorns) during fall, complemented by fleshy fruits, seems to boost reproductive success in Apennine female bears [37]. Although a substantial body of research has determined how forest management can affect habitat quality for black (Ursus americanus) (e.g., [38][39][40]) and grizzly (Ursus arctos) (e.g., [13,31,[41][42][43][44][45]) bears, no such information is currently available for Apennine brown bears [46]. To fill this knowledge gap, the aim of this study was to investigate the relationship between fine-scale forest structure metrics, reflecting forest structure and management practices, and indirect measures of productivity of key foods for Apennine bears.…”

Section: Introductionmentioning

confidence: 99%

Assessing Forest Structural and Topographic Effects on Habitat Productivity for the Endangered Apennine Brown Bear

Rositi¹,

Lasinio²,

Ciucci³

2021

Forests

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Any forest management potentially affects the availability and quality of resources for forest-dwelling wildlife populations, including endangered species. One such species is the Apennine brown bear, a small and unique population living in the central Apennines of Italy. The conservation of this relict bear population is hampered by the lack of knowledge of the fine-scale relationships between productivity of key foods and forest structure, as this prevents the design and implementation of effective forest management plans. To address this issue, we sampled the main structural stand attributes within the bear’s range and used multivariate generalized linear mixed models in a Bayesian framework to relate forest structural attributes to proxies of productivity of key bear foods. We found that hard mast was positively associated with both forest typology and high forest system, but negatively related to both the time elapsed since the last forest utilization and the amount of deadwood. The availability of soft-mast producing species was positively related to past forestry practices but negatively associated with steep slopes historically managed with high tree densities and a low silvicultural disturbance. Our findings also suggest that herb cover was negatively affected by terrain steepness and basal area, while herb productivity was positively affected by northern and southern exposure. Additionally, richness of forest ants was associated with forests characterized by low volume and high density. Our findings confirm that the productivity of natural bear foods is strongly affected by forest structural and topographical characteristics and are relevant as preliminary information for forest management practices to support the long-term conservation of Apennine bears.

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“…Hibernation is an essential part of bear ecology triggered by a decrease in available forage during winter and resulting in radical changes in bear behavior and metabolism (Hellgren 1998). The selection of a den site is an important decision for bear life history because dens provide shelter from harsh climatic factors and security from predators (Davis et al 2011, Libal et al 2011. Previous den studies have focused on denning chronology (Beecham et al 1983, Smith et al 1992, Beckmann and Berger 2003, Manchi and Swenson 2005, micro-scale habitat qualities (Pelton et al 1977, McLoughlin et al 2002, Baldwin and Bender 2008, and landscape-level patterns of den site selection (Gaines 2003, Ciarniello et al 2005, Reynolds-Hogland et al 2007, Elfström et al 2008, Waller et al 2013, Pigeon et al 2016.…”

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confidence: 99%