Energetics of hibernation and reproductive trade-offs in brown bears

López-Alfaro, Claudia; Robbins, Charles T.; Zedrosser, Andreas; Nielsen, Scott E.

doi:10.1016/j.ecolmodel.2013.09.002

Cited by 60 publications

(69 citation statements)

References 50 publications

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“…However, if dependent offspring are being captured in barb wire corrals, then the relationship between increased local bear abundance and the availability of fruit and ungulate matter may suggest that availability of complementary resources increases reproductive success and litter size and thus indicates areas of greater population performance. Female reproductive success of bears is influenced by their capacity to store both fat and lean mass before hibernation (Robbins et al , López‐Alfaro et al ), as well as the availability of food resources during the post‐denning lactation (spring) period, especially food resources high in protein which have been found to be important for bears (Noyce and Garshelis ). Fruit consumption during summer and early fall is an important source of energy that allows grizzly bears to accumulate fat mass prior to denning (McLellan ), as well as optimize their macronutrient intake and mass gain when combined with complementary resources (Coogan et al , Erlenbach et al ).…”

Section: Discussionmentioning

confidence: 99%

Complementary food resources of carnivory and frugivory affect local abundance of an omnivorous carnivore

Nielsen

Larsen²,

Stenhouse³

et al. 2016

Oikos

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A major unresolved question for omnivorous carnivores, like most species of bears, is to what degree are populations influenced by bottom–up (food supply) or top–down (human‐caused mortality) processes. Most previous work on bear populations has focused on factors that limit survival (top–down) assuming little effect of food resource supply. When food resources are considered, most often they consider only the availability/supply of a single resource, particularly marine‐subsidized or terrestrial sources of protein (carnivory) or alternately hard or soft mast (frugivory). Little has been done to compare the importance of each of these factors for omnivorous bears or test whether complementary resources better explain individual animal and population measures such as density, vital rates, and body size. We compared landscape patterns of digestible energy (kcal) for buffaloberry (a key source of carbohydrate) and ungulate matter (a key source of protein and lipid) to local measures in grizzly bear Ursus arctos abundance at DNA hair snag sites in west‐central Alberta, Canada. We tested support for bottom–up hypotheses in either single (carnivory [meat] versus frugivory [fruit]) or complementary (additive or multiplicative) food resources, while accounting for a well‐known top–down limiting factor affecting bear survival (road density). We found support for both top–down and bottom–up factors with complementary resources (co‐limitation) supported over single resource supplies of either meat or fruit. Our study suggests that the availability of food resources that provide complementary nutrients is more important in predicting local bear abundance than single foods or nutrients (e.g. protein) or simply energy per se. This suggests a nutritionally multidimensional bottom–up limitation for a low density interior population of grizzly bears.

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Section: Discussionmentioning

confidence: 99%

Complementary food resources of carnivory and frugivory affect local abundance of an omnivorous carnivore

Nielsen

Larsen²,

Stenhouse³

et al. 2016

Oikos

Self Cite

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show abstract

“…A similar link between human–bear conflicts and shorter denning period due to climate change has been suggested by several researchers (Servheen & Cross, ; Pigeon, ; Rayl et al ., ; Evans et al ., ). Furthermore, bear reproductive rates are strongly linked to energy reserves during hibernation and food availability immediately after hibernation (López‐Alfaro et al ., ). Foraging on abundant anthropogenic food during and after winter could artificially increase reproduction and local bear densities.…”

Section: Discussionmentioning

confidence: 97%

“…Bears exhibit several characteristics, such as lower reduction in body temperature, that separate them from the deep hibernation of many other mammals (Hissa, ; Hellgren, ; Evans et al ., ). Hibernation typically takes place in winter dens, which bears use to reduce energy loss when food is inadequate (Tietje & Ruff, ) and for pregnant females to give birth (López‐Alfaro et al ., ).…”

Section: Introductionmentioning

confidence: 97%

Winter sleep with room service: denning behaviour of brown bears with access to anthropogenic food

2016

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Large quantities of food subsidies provided by humans to animal communities have the potential to change a variety of animal life traits, including denning behaviour of facultative hibernators like bears. Brown bears Ursus arctos regularly use anthropogenic food, but it has remained unclear if human food subsidies affect their hibernation and denning behaviour, despite the consequences this could have for bear interactions with humans and other species. We studied denning behaviour of European brown bears in Slovenia, where intensive supplemental feeding with corn is practiced throughout the year, including winter. We used GPS telemetry data to locate den sites and to monitor bear denning chronology. We conducted a meta‐analysis to compare our results with other bear populations across Europe, Asia and North America. A consistent relationship between latitude and time spent denning was observed for male and female brown bears across the species’ range (for each degree of latitude northwards, denning period increased for 3.1 days), and males on average denned 10.3 days longer than females throughout the latitudinal gradient. However, our study area deviated strongly from regions where supplemental feeding was not practiced. In Slovenia, denning period averaged 82 days for females and 57 days for males, which was 45 and 56% shorter compared to the time predicted for this latitude, respectively. We also observed regular den abandonments (61% of bears abandoned dens, on average 1.9 times per winter). During the winter period bears increased use of supplemental feeding sites for 61% compared to the non‐denning period. We conclude that the availability of anthropogenic food is an important driver of denning behaviour in brown bears. Reduction in the denning period increases the potential for bear interactions with other species, including humans, and we highlight possible management and ecological implications of this human‐caused perturbation to denning behaviour of wild ursids.

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“…For instance, increasing body fat content correlates with earlier parturition date, longer lactation time and larger cub size at den emergence in grizzly bears (Robbins et al ). Female grizzly bears with insufficient body fat reserve at the beginning of hibernation may forgo embryo implantation completely (López‐Alfaro et al ). In polar and American black bears, female body fat content also strongly influences implantation likelihood and cub size at den emergence (Robbins et al ).…”

Section: Discussionmentioning

confidence: 99%

Comparative skeletal anatomy of neonatal ursids and the extreme altriciality of the giant panda

Smith

2019

Journal of Anatomy

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Mammalian neonates are born at a wide range of maturity levels. Altricial newborns are born with limited sensory agency and require extensive parental care. In contrast, precocial neonates are relatively mature physically and often capable of independent function shortly after birth. In extant mammals, placental newborns vary from altricial to precocial, while marsupials and monotremes are all extremely altricial at birth. Bears (family Ursidae) have one of the lowest neonatal−maternal mass ratios in placental mammals, and are thought to also have the most altricial placental newborns. In particular, giant pandas (Ailuropoda melanoleuca) are thought to be exceptionally altricial at birth, and possibly marsupial‐like. Here we used micro‐computer (micro‐computed) tomography scanning to visualize the skeletal anatomy of ursid neonates and compare their skeletal maturity with the neonates of other caniform outgroups. Specifically, we asked whether ursid neonates have exceptionally altricial skeletons at birth compared with other caniform neonates. We found that most bear neonates are similar to outgroup neonates in levels of skeletal ossification, with little variation in degree of ossification between ursine bears neonates (i.e. bears of the subfamily Ursinae). Perinatal giant pandas, however, have skeletal maturity levels most similar to a 42−45‐day‐old beagle fetus (~70% of total beagle gestation period). No bear exhibits the skeletal heterochronies seen in marsupial development. With regards to skeletal development, ursine bears are not exceptionally altricial relative to other caniform outgroups, but characterized largely by the drastic difference between newborn and adult body sizes. A review on the existing hypotheses for ursids’ unique reproductive strategy suggests that the extremely small neonatal−maternal mass ratio of ursids may be related to the recent evolution of large adult body size, while life history characteristics retained an ancestral condition. A relatively short post‐implantation gestation time may be the proximal mechanism behind the giant panda neonates’ small size relative to maternal size and altricial skeletal development at birth.

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Energetics of hibernation and reproductive trade-offs in brown bears

Cited by 60 publications

References 50 publications

Complementary food resources of carnivory and frugivory affect local abundance of an omnivorous carnivore

Complementary food resources of carnivory and frugivory affect local abundance of an omnivorous carnivore

Winter sleep with room service: denning behaviour of brown bears with access to anthropogenic food

Comparative skeletal anatomy of neonatal ursids and the extreme altriciality of the giant panda

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