Den selection by barren-ground grizzly bears, Mackenzie Delta, Northwest Territories

Smereka, Corey A.; Edwards, Mark; Pongracz, Jodie; Branigan, Marsha; Pilfold, Nicholas W.; Derocher, Andrew E.

doi:10.1007/s00300-016-1974-2

Cited by 8 publications

(8 citation statements)

References 63 publications

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“…The choice of a den and the landscape features of its surroundings may affect individual fitness Pigeon, Nielsen, Stenhouse, & Côté, 2014;Smereka et al, 2017). For example, if a pregnant female is forced to change her den during the winter, due to human disturbance or poor thermal qualities of the den, this can result in the loss of her offspring (Linnell et al, 2000).…”

Section: Den Characteristics and Surroundingsmentioning

confidence: 99%

“…Thick forest cover may better protect dens from wind and cold temperatures Pigeon et al, 2014), and thick vegetation cover also guarantees concealment of the den entrance and, thus, protection from human disturbance (Chirichella et al, 2019;Sahlén et al, 2011). Finally, in the case of excavated dens, trees roots may help ensure greater structural stability of the den (Ciarniello et al, 2005;Harding, 1976;Judd et al, 1986;Lentfer et al, 1972;Smereka et al, 2017;Vroom et al, 1980). In the case of excavated dens, brown bears also choose hibernation areas on the basis of lithological characteristics, selecting soils that not only are easier to dig but also increase den stability and insulating capacity (García, Lastra, Marquínez, & Nores, 2007;Harding, 1976;Manchi & Swenson, 2005;McLoughlin, Case, et al, 2002;Reynolds et al, 1976;Smereka et al, 2017;Vroom et al, 1980).…”

Section: Den Landscapesmentioning

confidence: 99%

“…Finally, in the case of excavated dens, trees roots may help ensure greater structural stability of the den (Ciarniello et al, 2005;Harding, 1976;Judd et al, 1986;Lentfer et al, 1972;Smereka et al, 2017;Vroom et al, 1980). In the case of excavated dens, brown bears also choose hibernation areas on the basis of lithological characteristics, selecting soils that not only are easier to dig but also increase den stability and insulating capacity (García, Lastra, Marquínez, & Nores, 2007;Harding, 1976;Manchi & Swenson, 2005;McLoughlin, Case, et al, 2002;Reynolds et al, 1976;Smereka et al, 2017;Vroom et al, 1980). Frequently, southeastern and southwestern slopes are preferred for greater insulation (Chirichella et al, 2019;Craighead & Craighead, 1972;Elfström et al, 2008;Harding, 1976;McLoughlin, Case, et al, 2002;Schoen et al, 1987;Štofík & Saniga, 2012).…”

Section: Den Landscapesmentioning

confidence: 99%

“…Frequently, southeastern and southwestern slopes are preferred for greater insulation (Chirichella et al, 2019;Craighead & Craighead, 1972;Elfström et al, 2008;Harding, 1976;McLoughlin, Case, et al, 2002;Schoen et al, 1987;Štofík & Saniga, 2012). Bears seem to prefer steeper slopes (Ciarniello et al, 2005;Elfström et al, 2008;Goldstein, Poe, Suring, Nielson, & McDonald, 2010;Libal et al, 2012;McLoughlin, Case, et al, 2002;Pigeon et al, 2014;Servheen & Klaver, 1983;Smereka et al, 2017;Sorum, Joly, Wells, Cameron, & Hilderbrand, 2019;Štofík & Saniga, 2012;Vroom et al, 1980) which may allow for the following: (a) simpler digging of the den compared with flat ground (McLoughlin, Case, et al, 2002;; (b) greater den structural resistance, reducing the likelihood of collapse (Ciarniello et al, 2005;Libal et al, 2012;Servheen & Klaver, 1983;Vroom et al, 1980); (c) large amounts of radiant heat (Ciarniello et al, 2005;Libal et al, 2012;Vroom et al, 1980); and (d) better protection against disturbances (Libal et al, 2011(Libal et al, , 2012Naves & Palomero, 1993).…”

Section: Den Landscapesmentioning

confidence: 99%

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Denning in brown bears

González-Bernardo

Russo

Valderrábano

et al. 2020

Ecology and Evolution

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Hibernation represents an adaptation for coping with unfavorable environmental conditions. For brown bears Ursus arctos, hibernation is a critical period as pronounced temporal reductions in several physiological functions occur. Here, we review the three main aspects of brown bear denning: (1) den chronology, (2) den characteristics, and (3) hibernation physiology in order to identify (a) proximate and ultimate factors of hibernation as well as (b) research gaps and conservation priorities. Den chronology, which varies by sex and reproductive status, depends on environmental factors, such as snow, temperature, food availability, and den altitude. Significant variation in hibernation across latitudes occurs for both den entry and exit. The choice of a den and its surroundings may affect individual fitness, for example, loss of offspring and excessive energy consumption. Den selection is the result of broad‐ and fine‐scale habitat selection, mainly linked to den insulation, remoteness, and availability of food in the surroundings of the den location. Hibernation is a metabolic challenge for the brown bears, in which a series of physiological adaptations in tissues and organs enable survival under nutritional deprivation, maintain high levels of lipids, preserve muscle, and bone and prevent cardiovascular pathologies such as atherosclerosis. It is important to understand: (a) proximate and ultimate factors in denning behavior and the difference between actual drivers of hibernation (i.e., factors to which bears directly respond) and their correlates; (b) how changes in climatic factors might affect the ability of bears to face global climate change and the human‐mediated changes in food availability; (c) hyperphagia (period in which brown bears accumulate fat reserves), predenning and denning periods, including for those populations in which bears do not hibernate every year; and (d) how to approach the study of bear denning merging insights from different perspectives, that is, physiology, ecology, and behavior.

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Section: Den Characteristics and Surroundingsmentioning

confidence: 99%

Section: Den Landscapesmentioning

confidence: 99%

Section: Den Landscapesmentioning

confidence: 99%

Section: Den Landscapesmentioning

confidence: 99%

See 2 more Smart Citations

Denning in brown bears

González-Bernardo

Russo

Valderrábano

et al. 2020

Ecology and Evolution

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“…Knowledge about patterns of habitat selection is often needed in order to make evidence-based management decisions. For instance, Smereka et al [ 1 ] mapped the relative probability of selection for den sites for grizzly bears ( Ursus arctos horibilis ) in the Mackenzie Delta, Northwest Territories, Canada, to reduce human-bear conflicts by guiding human activity and land-use. A habitat selection model [ 2 ] has also been applied to harvest management of willow ptarmigan ( Lagopus lagopus ) in Northern Norway, where quotas are estimated based on a combination of pre-harvest densities and the amount of suitable habitat for willow ptarmigan available within the hunting area.…”

Section: Introductionmentioning

confidence: 99%

Quantifying suitable late summer brood habitats for willow ptarmigan in Norway

2018

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BackgroundHabitat models provide information about which habitat management should target to avoid species extinctions or range contractions. The willow ptarmigan inhabits alpine- and arctic tundra habitats in the northern hemisphere and is listed as near threatened (NT) in the Norwegian red list due to declining population size. Habitat alteration is one of several factors affecting willow ptarmigan populations, but there is a lack of studies quantifying and describing habitat selection in willow ptarmigan. We used data from an extensive line transect survey program from 2014 to 2017 to develop resource selection functions (RSF) for willow ptarmigan in Norway. The selection coefficients for the RSF were estimated using a mixed-effects logistic regression model fitted with random intercepts for each area. We predicted relative probability of selection across Norway and quantile-binned the predictions in 10 RSF bins ranging from low-(1) to high-(10) relative probability of selection.ResultsRandom cross-validation suggest that our models were highly predictive, but validation based spatial blocking revealed that the predictability was better in southern parts of Norway compared to the northernmost region. Willow ptarmigan selected for herb-rich meadows and avoided lichen rich heathlands. There was generally stronger selection for vegetation types with dense field layer and for rich bogs and avoidance of vegetation types with sparse field layer cover and for lowland forest. Further, willow ptarmigan selected for areas around the timberline and for intermediate slopes. Mapping of the RSF showed that 60% of Norway is in the lowest ranked RSF bin and only 2% in the highest ranked RSF bin.ConclusionsWillow ptarmigan selected for vegetation types with dense field layer and bogs at intermediate slopes around the timberline. Selection coincides with previous habitat selection studies on willow ptarmigan. This is the first attempt to assess and quantify habitat selection for willow ptarmigan at a large scale using data from line transect distance sampling surveys. Spatial variation in predictability suggests that habitat selection in late summer might vary from north to south. The resource selection map can be a useful tool when planning harvest quotas and habitat interventions in alpine areas.

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Room without a view—Den excavation in relation to body size in brown bears

Shiratsuru

Friebe²,

Swenson

et al. 2020

Ecology and Evolution

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Hibernation is an adaptive strategy to survive harsh winter conditions and food shortage. The use of well‐insulated winter dens helps animals minimize energy loss during hibernation. Brown bears ( Ursus arctos ) commonly use excavated dens for hibernation. Physical attributes of excavated dens are expected to impact the bear's heat retention and energy conservation. The objective of this study was to examine the determinants of cavity size of excavated dens and the impact of physical attributes of excavated dens on energy conservation in hibernating bears, hypothesizing that bears excavate dens in a way to minimize heat loss and optimize energy conservation during hibernation. We predicted that den cavity size would be determined by the bear's body size and that older bears would excavate better‐fitting cavities to minimize heat loss, due to their previous experience. We further predicted that physical attributes of excavated dens would affect the bears’ posthibernation body condition. Our results revealed that bears excavated a den cavity in relation to their body size, regardless of sex, and that older bears tended to excavate better‐fitting den cavities compared to young bears, as we expected. Older bears excavated better‐fitting den cavities, suggesting a potentially experience‐based shift with age in den‐excavation behavior and an optimum cavity size relative to a bear's body size. Our key finding is that insulation of excavated dens provided by wall/rood thickness and bedding materials had a significant positive effect on bears’ posthibernation body condition. We believe that our study provides new insight into how not only the quality of denning habitat, but also the quality of dens may affect hibernating animals, by presenting a potential adaptive aspect of den preparation (age effect on efficiency in den excavation) and effect of den attributes on the posthibernation body condition of brown bears.

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Den selection by barren-ground grizzly bears, Mackenzie Delta, Northwest Territories

Cited by 8 publications

References 63 publications

Denning in brown bears

Denning in brown bears

Quantifying suitable late summer brood habitats for willow ptarmigan in Norway

Room without a view—Den excavation in relation to body size in brown bears

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