Volume 105, July 2015, Pages 79–84
- a Department of Evolutionary Studies of Biosystems, The Graduate University for Advanced Studies, Kanagawa, Japan
- b Department of Life Science, Rikkyo University, Tokyo, Japan
- Received 16 January 2015, Revised 9 February 2015, Accepted 2 April 2015, Available online 16 May 2015
- MS. number: 15-00040
Highlights
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- We tested whether a bent posture enhances bird dropping masquerade in caterpillars.
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- Bent posture improved the survival of bird dropping-coloured caterpillar models.
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- Bent posture did not affect the survival rate of green caterpillar models.
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- We show for the first time the protective value of posture in masquerading prey.
Masquerade
describes a defence by animals that have evolved to closely resemble
inedible objects such as twigs, stones or bird droppings. Animals that
masquerade often match their models in size or shape, and may even adopt
specific postures in order to enhance their resemblance, causing
predators to misclassify them as their model objects. The caterpillars
of some moth species resemble bird droppings, and bend their bodies
while resting on branches or leaves. We hypothesized that such bending
might enhance the caterpillars' resemblance to real bird droppings. In
this study, we tested this hypothesis by pinning artificial caterpillars
with green or bird dropping coloration onto tree branches in both
straight and bent postures, after which we exposed them to bird
predation in the wild. We found that the adoption of a bent posture
resulted in a lower attack rate by birds on the artificial caterpillars
with the bird dropping coloration, while green caterpillars experienced
no benefit from the same treatment. This study is the first experimental
demonstration of the protective value of a specific posture in
masquerading prey, and highlights the importance of considering an
organism's shape and posture in the study of masquerade.
Keywords
- bird dropping masquerade;
- caterpillar;
- defensive coloration;
- posture;
- predation
Copyright © 2015 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.
