Relative size and nose color predict age in Andean bears, but their facial markings do not reflect kinship

Using photos of captive Andean bears of known age and pedigree, and photos of wild Andean bear cubs < 6 months old, we evaluated the degree to which visual information may be used to estimate bears’ ages and assess their kinship. We demonstrate that the ages of Andean bear cubs ≤ 6 months old may be estimated from their size relative to their mothers with an average error of < 0.01 ± 13.2 days (SD; n = 14), and that ages of adults ≥ 10 years old may be estimated from the proportion of their nose that is pink with an average error of < 0.01 ± 3.5 years (n = 41). We also show that similarity among the bears’ natural markings, as perceived by humans, is not associated with pedigree kinship among the bears (R2 < 0.001, N = 1,043, p = 0.499). Thus, researchers may use photos of wild Andean bears to estimate the ages of young cubs and older adults, but not to infer their kinship. Given that camera trap photos are one of the most readily available sources of information on large cryptic mammals, we suggest that similar methods be tested for use in other poorly understood species.