Russell C. Van Horn, Garth Mowat, Rebecca Zug

Size and body condition of wild bears are known to reflect their ecology, especially habitat quality, and have been found to be associated with variation in female reproductive success. These data could inform decisions impacting bear conservation. However, data on reproductive success and habitat quality are difficult to obtain from wild Andean bears (Tremarctos ornatus). To obtain such data, we integrated noninvasive visual morphometry with camera trapping to estimate variables reflecting bear body size and body condition in free-ranging Andean bears. We analyzed images collected at 60 camera stations deployed from Jun 2022 - Nov 2023 in the Manu Biosphere Reserve (MANU) of southeastern Peru. In each detection of an individually identifiable bear of known sex, we attempted to estimate 5 body dimensions reflecting body size (e.g., Representative Body Length, RBL) and 2 dimensions reflecting body condition (e.g., Dorsal-Ventral Height, DVH). Among Manu bears, male RBL (n=12) was 131.6±17.6cm, 23% larger than the female RBL (n=2) of 106.7±9.4cm. Male DVH was 40.5±8.0cm, 23% greater than the female DVH of 33.0±0.8cm. These differences are consistent with sexual dimorphism that has not been previously quantitatively reported in the wild population, but rather in zoo bears. Our data suggest that the seasonally labile measures of body size (DVH) index changes in body condition when standardized by body length. We will present body size and body condition from the subsequent 3 years of imagery from MANU, and from 2023-2025 imagery from 45 camera stations in northeast Peru, which are the first quantitative comparisons of body size and body condition within and between Andean bear populations. These data will be the first step to incorporating habitat quality across Peruvian landscapes that can be used as a source to guide conflict prevention and improve bear well-being through management actions.