MASS AND BODY-DIMENSION RELATIONSHIPS OF POLAR BEARS IN NORTHERN ALASKA

Models developed from morphometric parameters are useful for estimatin g body mass (M) of captured wild ursids. The accuracy of those models, however, may depend on sex, season, and geographic location of the po pulation. We tested the suitability of reported models to predict mass of polar bears (Ursus maritimus) captured in northern Alaska, but fou nd that models developed for other populations performed poorly. Hence , we derived new models from field measurements of axillary girth (AG) , straight-line body length (SLBL), condylobasal length (CL), and zygo matic width (ZW). Our equations accurately predicted body mass for pol ar bears captured during spring and autumn. The equation for spring-ca ptured polar bears was M = 0.000078 AC(1.6026) * SLBL(1.3579) (R(2) = 0.97), while the equation for autumn-captured polar bears was M = 0. 000250 A(1.4967) * SLBL(1.2468) (R(2) = 0.97). Our results suggest t hat investigators should verify the accuracy of reported equations whe n applied to each situation and if necessary, develop models specific for the population in question.