AnAge entry for Ursus americanus

Lifespan, ageing, and relevant traits

During hibernation body temperature floats around 32.5ºC. Although pregnancy in bears lasts for about 220 days, there is a delayed implantation and embryonic development only occurs in the last 10 weeks of pregnancy [0434]. In the wild, it has been suggested that they may live over 33 years [0558], which is dubious. Record longevity in captivity belongs to a wild born female that was about 34 years when she died in captivity [0671].

Life history traits (averages)

Metabolism

References

[0671] Richard Weigl (2005), Longevity of Mammals in Captivity; from the Living Collections of the World
[0559] Freedman et al. (2003), Life history analysis for black bears (Ursus americanus) in a changing demographic landscape
[0610] Ernest (2003), Life history characteristics of placental non-volant mammals
[0434] Ronald Nowak (1999), Walker's Mammals of the World
[0079] Uchida et al. (1995), Senile plaques and other senile changes in the brain of an aged American black bear, PubMed
[0676] Purvis and Harvey (1995), Mammal life-history evolution: a comparative test of Charnov’s model
[0455] Virginia Hayssen et al. (1993), Asdell's Patterns of Mammalian Reproduction: A Compendium of Species-Specific Data
[0680] Wootton (1987), The effects of body mass, phylogeny, habitat, and trophic level on mammalian age at first reproduction
[0731] Zullinger et al. (1984), Fitting sigmoid equations to mammalian growth curves
[0558] North American Bear Center

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