Variation in life history and demography in the American black bear

Background/Question/Methods   Variation in life history and demography across a species' range informs researchers about regional adaptations and affects whether managers can borrow information from other populations in decision-making. The American black bear is a long-lived game species whose continued persistence depends on management of harvest and nuisance removals. Understanding the demography of black bears guides efforts at management and conservation. I performed a hierarchical Bayesian meta-analysis of black bear demographic studies to explore how vital rates vary across its range, what information they give us about life history and population growth, and whether managers can justify borrowing information from other studies to inform management decisions.

Results/Conclusions   Cub, yearling, and adult survival and fecundity varied between eastern and western North America, while subadult survival did not show geographic structuring. Adult survival and fecundity appear to trade off, with higher survival in the west and higher fecundity in the east. Although adult survival had the highest elasticity, differences in reproduction drove differences in population growth rate. The mean population growth rate was higher in the east, 1.00 (0.96, 1.04), than the west, 0.98 (0.94, 1.01). Despite declining trends in the west, 35% of the populations there were estimated to be increasing. Further work needs to be done to address the cause of the apparent relationship between adult survival and fecundity and explore how the estimated growth rates are likely to affect population status of black bears. Because population growth rates are close to one and small deviations could impact whether a population is considered increasing or decreasing, managers should employ caution in borrowing vital rates from other populations.