Are chest marks unique to Asiatic black bear individuals?

Estimating population size based on a capture-recapture model requires identification of individual animals. We evaluated the reliability of the chest mark to noninvasively identify individual Asiatic black bears Ursus thibetanus. Using image analysis, we collated the chest marks of bears from the photographs taken while the bears were in captivity (Ani Mataginosato Bear Park) to examine the universality, uniqueness and persistence of the marks. Of the 62 bears, 95% had a distinct chest mark by which they could be reliably identified, and the probability of mistakenly identifying two different bears as identical was calculated to be 0.00075. The shape of the mark was found to change slightly from year to year, but this did not hamper individual identification. Thus, individual identification of the bears was highly reliable. A high percentage of correct answers was obtained in a blind test to visually identify individuals based on their chest mark. Considering that it is both an inexpensive and an easy-to-use technique, chest mark comparison is suitable for individual identification in order to estimate the abundance of the black bear population.