The influence of body size, condition, and age on recruitment of four Alaskan brown bear populations

By: , and 



Recruitment of brown bear (Ursus arctos) offspring into a population is the product of initial cub production and subsequent survival and is a critical component of overall population status and trend. We investigated the relationship between maternal body size, body condition, and age (as a surrogate for gained experience) and recruitment of dependent offspring (≥1 yr old) in 4 Alaska, USA (2014–2017), brown bear populations using logistic regression. Body size alone was our top predictor of the presence of offspring and appeared in all top models. Our data suggest that bear size is the primary driver of productivity across all 4 study populations, with larger bears having a greater chance of being observed with offspring. The effect of body condition was likely confounded by the increased energetic costs of supporting cubs through time and had a negative relationship with recruitment. Age (experience) was positively related to recruitment. Understanding the relative importance of body size, body condition, and age on the recruitment of offspring provides insights into life-history trade-offs female bears must manage as they strive to meet the nutritional costs of cub production and rearing, while minimizing risks to themselves and their offspring. Further assessment of long-term longitudinal studies of brown bears that assess the lifetime reproductive output of individuals would be highly informative to further assess the effect of experience on recruitment and to support the management of brown bear populations for recovery, conservation, sustained yield, and ecosystem function.

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Publication type Article
Publication Subtype Journal Article
Title The influence of body size, condition, and age on recruitment of four Alaskan brown bear populations
Series title Ursus
DOI 10.2192/URSUS-D-18-00008.1
Volume 2
Issue 29
Year Published 2019
Language English
Publisher BioOne
Contributing office(s) Alaska Science Center, Alaska Science Center Biology MFEB, Alaska Science Center Biology WTEB
Description 8 p.
First page 111
Last page 118
Country United States
State Alaska
Other Geospatial Brooks Range, Gates of the Arctic National Park & Preserve, Katmai National Park & Preserve, Kodiak National Wildlife Refuge, Lake Clark National Park & Preserve
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