Carrion Seeking in Brown Tree Snakes: Importance of Olfactory and Visual Cues

We performed field experiments to examine brown tree snake (Boiga irregularis) attraction to carrion. These snakes were attracted to carrion and entered traps baited with dead mice as readily as traps baited with live mice. Using the cues arising from both live and dead prey, we examined the relative importance of visual and chemical cues to brown tree snakes. With carrion lures, chemical cues alone were sufficient for attracting and capturing snakes, but with live prey lures visual cues were required to attract and capture brown tree snakes. Our study presents the first experimental field evidence showing carrion to be attractive to an ophidian predator and suggests that the relative importance of chemical and visual sensory stimuli to brown tree snakes is context-specific. J. Exp. Zool. 279:549–553, 1997. © 1997 Wiley-Liss, Inc. Visual and chemical stimuli provide critical information to snakes about the type and location of prey. The importance of one stimulus over another varies according to the species of snake and the context of the stimulus. For example, chemical cues stimulate appetitive behavior in garter snakes and rattlesnakes (Thamnophis spp. and Crotalus spp.) (Burghardt, ’69; Burghardt et al., ’88; Chiszar et al., ’90; Cowles and Phelan, ’58; Duvall et al., ’90; Ford and Low, ’84; Golan et al., ’82; Heller and Halpern, ’81). Gopher snakes (Pituophis catenifer) and rat snakes (Elaphe obsoleta) use visual and/or chemical cues to find arboreal prey (Eichholz and Koenig, ’92; Neal et al., ’93). Brown tree snakes may respond to olfactory cues, be primarily visually guided, or switch between modalities when cues are ambiguous (Chiszar et al., ’88; Chiszar, ’90; Fritts et al., ’89; Lankford, ’89). The relative importance of visual and olfactory stimuli to foraging brown tree snakes appears to be dependent upon which cues are simultaneously presented (Chiszar, ’90), but recent data suggest that, at least for live prey, visual and odor cues act synergistically to promote foraging behaviors in brown tree snakes (Shivik,