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Comments on Guimarães & Sawaya. Pretending to be venomous: is a snake's head shape a trustworthy signal to a predator?

Published online by Cambridge University Press:  08 December 2011

Janne K. Valkonen  and
Johanna Mappes
Janne K. Valkonen*
Affiliation:
Centre of Excellence in Evolutionary Research, Department of Biological and Environmental Science, P.O. Box 35, 40014University of Jyväskylä, Finland
Johanna Mappes
Affiliation:
Centre of Excellence in Evolutionary Research, Department of Biological and Environmental Science, P.O. Box 35, 40014University of Jyväskylä, Finland
*
1Corresponding author. Email: [email protected]
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Extract

Several species of non-venomous snake are known to flatten their heads when disturbed, and this behaviour has been suggested to be a mimicry of vipers (Arnold & Ovenden 2002, Hailey & Davies 1986, Young et al. 1999). Using plasticine models, Guimarães & Sawaya (2011) tested the antipredatory function of a triangular head shape in snakes. Their article presents the first published empirical experiment testing the adaptive significance of vipers' triangular head shape. Guimarães & Sawaya (2011) found no support for the viper mimicry hypothesis. Accordingly, they concluded that ‘the shape of [the] head seemed not to confer advantage itself’. Although the use of plasticine models is a generally accepted method of testing predation pressure on snakes, we argue that the experiment may have failed to find the antipredatory function of triangulation due to the pooling of attacks by mammalian and avian predators. Mammals generally rely on olfactory cues during foraging. Plasticine has a strong odour which does not resemble the odour of any prey species. It is thus unlikely that mammals would treat snake replicas as true snakes.

Keywords

defencehead triangulationmimicrymorphologyplasticine replicaspredationsnakes
Type
Short Communication
Information
Journal of Tropical Ecology , Volume 28 , Issue 1 , January 2012 , pp. 123 - 124
Copyright
Copyright © Cambridge University Press 2011

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References

LITERATURE CITED

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