Experienced chicks show biased avoidance of stronger signals: an experiment with natural colour variation in live aposematic prey |
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Authors: | Gabriella Gamberale-Stille Birgitta S Tullberg |
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Institution: | (1) Department of Zoology, Stockholm University, Sweden |
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Abstract: | An important factor for understanding the evolution of warning coloration in unprofitable prey is the synergistic effect produced
by predator generalisation behaviour. Warning coloration can arise and become stabilised in a population of solitary prey
if more conspicuous prey benefit from a predator's previous interaction with less conspicuous prey. This study investigates
whether domestic chicks (Gallus gallus domesticus) show a biased generalisation among live aposematic prey by using larvae of three species of seed bugs (Heteroptera: Lygaeidae)
that are of similar shape but vary in the amount of red in the coloration. After positive experience of edible brownish prey,
chicks in two reciprocal experiments received negative experience of either a slightly red or a more red distasteful larva.
Attacking birds were then divided into two treatment groups, – one presented with the same prey again, and one presented with
either a less red or a more red larva. Birds with only experience of edible prey showed no difference in attack probability
of the two aposematic prey types. Birds with experience of the less red prey biased their avoidance so that prey with a more
red coloration was avoided to a higher degree, whereas birds with experience of the more red prey avoided prey with the same,
but not less red coloration. Thus, we conclude that bird predators may indeed show a biased generalisation behaviour that
could select for and stabilise an aposematic strategy in solitary prey.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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Keywords: | aposematism defence Graptostethus servus Lygaeus equestris predation stimulus generalization synergism Tropidothorax leucopterus |
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