SERUM CHEMISTRY OF SOUTHERN-POPULATIONS OF BLACK BEARS (URSUS-AMERICANUS)

Serum metabolites change seasonally in black bears (Ursus americanus) in northern temperate regions. We studied variation in serum chemistry and hematology in populations of black bears from southern Florida (n = 55) and northern Coahuila, Mexico (n = 44). Our objective was to ev aluate the magnitude of seasonal changes in metabolic indicators in th ese bears, which exhibited only facultative hibernation. We predicted that seasonal shifts would be smaller than in northern climates. Nine blood characteristics varied (P < 0.05) across seasons, with similar p atterns observed across study areas for six of these variables. Serum chemistries tracked changes in diet. Red blood cell concentration(in F lorida only) varied by a season-cohort interaction (P = 0.03) and hema tocrit had a similar tendency (P < 0.10) on both areas, with increased red blood cell counts and hematocrits observed for adult females and subadult males, but not adult males, in autumn. Overall, reduced or ab sent hematological cycles in Mexico and Florida were consistent with o ur prediction of dampened cyclic amplitude in southern latitudes. Our data also supported the hypothesis that changes in hematopoiesis are a daptive to the hibernating state in the black bear.