Black Bear Reactions to Venomous and Non-venomous Snakes in Eastern North America.

Bears are often considered ecological equivalents of large primates, but the latter often respond with fear, avoidance, and alarm calls to snakes, both venomous and non-venomous, there is sparse information on how bears respond to snakes. We videotaped or directly observed natural encounters between black bears (Ursus americanus) and snakes. Inside the range of venomous snakes in Arkansas and West Virginia, adolescent and adult black bears reacted fearfully in seven of seven encounters upon becoming aware of venomous and non-venomous snakes; but in northern Michigan and Minnesota where venomous snakes have been absent for millennia, black bears showed little or no fear in four encounters with non-venomous snakes of three species. The possible roles of experience and evolution in bear reactions to snakes and vice versa are discussed. In all areas studied, black bears had difficulty to recognize non-moving snakes by smell or sight. Bears did not react until snakes moved in 11 of 12 encounters with non-moving timber rattlesnakes (Crotalus horridus) and four species of harmless snakes. However, in additional tests in this study, bears were repulsed by garter snakes that had excreted pungent anal exudates, which may help explain the absence of snakes, both venomous and harmless, in bear diets reported to date.

Fatal disseminated blastomycosis in a free-ranging American black bear (Ursus americanus).

An aged, free-ranging, female, radio-collared American black bear (Ursus americanus) died after an approximately 5 month long period of weight loss. Gross necropsy findings included severe diffuse pyogranulomatous bronchopneumonia, marked granulomatous lymphadenitis of tracheobronchial lymph nodes and multiple intra-abdominal lymph nodes, chronic focal jejunal ulceration, and widespread alopecia. Histopathologic examination revealed abundant fungal organisms morphologically compatible with Blastomyces sp. within pyogranulomatous inflammatory lesions in the lungs, multiple lymph nodes, liver, kidneys, jejunum, and right adrenal gland. In addition, the haircoat had a mild infestation of chewing lice (Trichodectes pinguis euarctidos), and large numbers of rhabditid nematodes consistent with Pelodera sp. were histologically observed within hair follicles.