Snakes as hazards: modelling risk by chasing chimpanzees
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Snakes are presumed to be hazards to primates, including humans, by the snake detection hypothesis (Isbell in J Hum Evol 51:1–35, 2006; Isbell, The fruit, the tree, and the serpent. Why we see so well, 2009). Quantitative, systematic data to test this idea are lacking for the behavioural ecology of living great apes and human foragers. An alternative proxy is snakes encountered by primatologists seeking, tracking, and observing wild chimpanzees. We present 4 years of such data from Mt. Assirik, Senegal. We encountered 14 species of snakes a total of 142 times. Almost two-thirds of encounters were with venomous snakes. Encounters occurred most often in forest and least often in grassland, and more often in the dry season. The hypothesis seems to be supported, if frequency of encounter reflects selective risk of morbidity or mortality.
KeywordsPan troglodytes Serpentes Danger Encounter rate
Thanks to: Direction des Parcs Nationaux du Senegal for permission to do field research; American Philosophical Society, Carnegie Trust for the Universities of Scotland, Leakey Foundation, Science Research Council (UK), Wenner-Gren Foundation for Anthropological Research for funding; Leverhulme Trust for supporting the writing-up of the results; 15 colleagues, especially the late Pamela Baldwin, Caroline Tutin, and Richard Byrne, for collecting data; Alejandra Pascual-Garrido, Gordon Burghardt, and two anonymous reviewers for helpful comments on the manuscript. This paper is dedicated to Prof. Charles C. Carpenter, who mentored my youthful interests in herpetology.
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