Behavioural complexity and prey-handling ability in snakes: gauging the benefits of constriction

Authors: Bealor, Matthew T.; Saviola, Anthony J.

Source: Behaviour, Volume 144, Number 8, 2007 , pp. 907-929(23)

Publisher: BRILL

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Abstract:

Complexity is an important component of behaviour, but is rarely defined or quantitatively analyzed. We tested the hypothesis that complex behaviours are functionally superior to simpler behaviours. We generated complexity values for prey-handling behaviours used by snakes based on a count of behavioural acts, coordination among acts, and the amount of the snake's body used to subdue prey. We then compared prey-handling ability between species that differed in the complexity of behaviour used to subdue mice (Mus musculus). Corn and ratsnakes (Pantherophis guttata and P. obsoleta) always constricted mice while coachwhips (Masticophis flagellum) used simpler behaviours including jaw hold and body pinning. The constrictors required fewer strikes, less time to capture and subdue mice, and killed prey more quickly than did the coachwhips. Both jaw holding and constriction resulted in severe compression of the prey, but during constriction force is exerted at many points around the prey, while using the jaws limits force exertion to two opposing surfaces. Constriction divides the tasks of seizure and subjugation between the snake's head and body, thus reducing the number of tasks the jaws must perform. Our results support the idea that constriction is an adaptation for subduing vigorously struggling prey.

Keywords: BEHAVIOURAL COMPLEXITY; PREY-HANDLING; CONSTRICTION; SNAKE FEEDING BEHAVIOUR

Document Type: Research article

DOI: http://dx.doi.org/10.1163/156853907781492690

Affiliations: 1: Ecology and Evolutionary Biology, University of Colorado at Boulder, Boulder, CO 80309-0334, USA

Publication date: 2007-08-01