Rogers Lynn L, Mansfield Susan A, Hornby Kathleen, Hornby Stewart, Debruyn Terry D, Mize Malvin, Clark Rulon, Burghardt Gordon M
Wildlife Research Institute Ely, MN, USA.
Wildernest Inn Upper Tract, WV, USA.
Ethology. 2014 Jul;120(7):641-651. doi: 10.1111/eth.12236. Epub 2014 Mar 27.
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 () 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 () 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.
熊通常被认为在生态上等同于大型灵长类动物，但后者往往会对有毒和无毒的蛇产生恐惧、躲避并发出警报叫声，而关于熊如何应对蛇的信息却很少。我们拍摄了黑熊（ ）与蛇自然相遇的视频或直接进行了观察。在阿肯色州和西弗吉尼亚州有毒蛇的活动范围内，青少年和成年黑熊在意识到有毒和无毒蛇时，在七次相遇中有七次表现出恐惧反应；但在密歇根州北部和明尼苏达州，数千年来一直没有毒蛇，黑熊在与三种无毒蛇的四次相遇中几乎没有表现出恐惧。本文讨论了经验和进化在熊对蛇的反应中的可能作用，反之亦然。在所有研究区域，黑熊很难通过嗅觉或视觉识别静止不动的蛇。在与静止不动的木纹响尾蛇（ ）和四种无害蛇的12次相遇中，有11次蛇移动之前熊没有反应。然而，在本研究的其他测试中，熊被排出刺鼻肛门分泌物的束带蛇击退，这可能有助于解释迄今为止报道的熊的饮食中没有有毒和无害蛇的原因。
