We evaluated the efficiency of an extension of a single season capture–mark–recapture (CMR) population estimation method, a closed-capture robust-design model, to monitor trends in population size, apparent survival, and temporary emigration rates over a 5-year period for a low-density population of American black bears (Ursus americanus) in north central Utah, USA. We also used robust-design Pradel models to estimate finite rate of population change and recruitment. We identified individual bears through genetic analysis of tissue samples collected non-invasively at scent-lured sampling sites. Although the population was relatively small ( = 15–22), the Huggins robust-design model provided precise estimates of abundance (CV = 8–14%) and female apparent survival (CV = 9%). Apparent survival for females (φ = 0.80, SE = 0.07) was 2.2× higher than for males (φ = 0.36, SE = 0.12; P = 0.003). In contrast, temporary emigration was 40.8× higher for males (γ″ = 0.58, SE = 0.24) than for females (γ″ = 0.004, SE = 0.06; P = 0.024). Data were insufficient to estimate probability of staying for either sex. From the Pradel model, finite rate of population change was similar for males and females (λ = 1.05, SE = 0.12 for females; λ = 1.11, SE = 0.16 for males), but recruitment was 3.0× higher for males (f = 0.75, SE = 0.17) than for females (f = 0.25, SE = 0.10; P = 0.013). Population size appeared to be stable or slightly increasing over the 5-year period. This noninvasive CMR study provided relatively efficient, precise estimates of a low-density black bear population on a small study site. We recommend using robust-design closed-capture models if samples are taken over multiple years; in addition to population size, apparent survival, movement, recruitment, and finite population change can be estimated, providing timely insights into population trends and the mechanisms driving them.
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Vol. 23 • No. 1