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1 July 2017 Counts of unique females with cubs in the Apennine brown bear population, 2006–2014
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Abstract

Brown bears (Ursus arctos marsicanus) in the Apennines, central Italy, survive in a precarious conservation status but the reproductive performance of the population has never been formally assessed. Each year, from 2006 to 2014, we conducted surveys of females with cubs (FWC) to estimate the minimum number of female bears that reproduced and annual productivity in this bear population. We discriminated unique family groups based on simultaneity of sightings, presence of individually recognizable bears, and ad hoc distance-based rules developed using Global Positioning System relocations from 11 adult female bears in our study population. To estimate the true number of FWC from unique counts, we applied 2 estimators (Chao2, Capwire) known to handle heterogeneity in sighting probabilities relatively well at small sample sizes. Annually, we estimated 1–6 ( = 3.9 ± 1.5 SD) unique FWC and tallied a minimum of 3–11 ( = 7.4 ± 3.0 SD) cubs in the population. No temporal trend in FWC was observed and the mean estimate of reproductive females corresponded well with an independent estimate of total population size obtained in 2011. Although we confirmed that the population is still reproductively functional, the small number of reproducing females and their year-to-year fluctuations dramatically underlined the precarious status of Apennine bears. We concur with previous authors that counts of unique FWC are an effective means to assess reproductive output in small bear populations, although it is advisable that more in-depth demographic studies complement this technique.

© 2017 International Association for Bear Research and Management
Elisabetta Tosoni, Luigi Boitani, Gianluca Mastrantonio, Roberta Latini, and Paolo Ciucci "Counts of unique females with cubs in the Apennine brown bear population, 2006–2014," Ursus 28(1), 1-14, (1 July 2017). https://doi.org/10.2192/URSU-D-16-00022.1
Received: 8 September 2016; Accepted: 1 January 2017; Published: 1 July 2017
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