Elsevier

Animal Behaviour

Volume 81, Issue 4, April 2011, Pages 825-829
Animal Behaviour

Colour biases are a question of conspecifics’ taste

https://doi.org/10.1016/j.anbehav.2011.01.017Get rights and content

Toxic prey often advertise their defences to predators using conspicuous colours, such as red and yellow; and predators exhibit unlearned biases against warningly coloured food. These biases are particularly evident when other components of warning displays, such as sounds and odours, are present. Predators are thought to use additional signal components to reduce their attack rates on warningly coloured prey when the risk of them being defended is perceived to be high. If this is the case, any cue that allows predators to predict the presence of defended prey reliably should incite biases against warningly coloured food. Using domestic chicks, Gallus gallus domesticus, as predators and coloured crumbs for prey, I tested whether observing a conspecific’s distaste response caused predators to bias their foraging decisions away from warningly coloured prey. Chicks observed a conspecific that had been given either a drop of water or a drop of Bitrex (a bitter-tasting solution). They were then offered a choice of either red and green, or yellow and green crumbs. Chicks that observed a conspecific’s reaction to Bitrex attacked fewer red and yellow crumbs, and more green crumbs, than chicks that observed a conspecific’s reaction to water. Observing conspecifics’ disgust responses therefore caused birds to bias their foraging preference away from warningly coloured food and towards food of a more neutral colour. This suggests that predators’ social systems may play a more important role than previously thought in the evolution of prey defences.

Section snippets

Subjects and Housing

Forty-five domestic chicks, Gallus gallus domesticus, that were hatched in the laboratory served as experimental subjects in experiment 1 (30 experimental chicks and 15 demonstrator chicks; see below for details); and a further 24 served as experimental subjects in experiment 2 (16 experimental chicks and eight demonstrator chicks). ‘Experimental chicks’ observed the responses of ‘demonstrator chicks’ to either a palatable or a bitter solution. The food colour preferences of experimental chicks

Results

All of the experimental birds went on to attack 16 of the coloured crumbs after observing the demonstrator (but not the substance that elicited the demonstrator’s response). An attack was either pecking or eating a crumb since both these behaviours show a clear food choice. In experiment 1, the number of red crumbs attacked differed between the two experimental groups: birds in the Bitrex group attacked significantly fewer red crumbs than birds in the Water group (Mann–Whitney test: U = 25.5, N1 = N

Discussion

These experiments clearly demonstrate that observing a conspecific’s distaste response causes naïve birds to bias their foraging preferences away from red and yellow crumbs (colours typically associated with insect warning patterns) and towards food of a more neutral colour (green). This is despite the fact that the disgust responses of birds’ conspecifics were not associated with any particular colour signal. Furthermore, the number of distaste responses that demonstrators performed was

Acknowledgments

I thank Michelle Waddle and Lin Hedgecock for looking after the birds and Cheryl Crozier for help in the laboratory. This work was supported by a Lloyd’s Tercentenary Foundation Fellowship.

References (37)

  • W. Schuler et al.

    Responses to warning coloration in avian predators

    Advances in the Study of Behaviour

    (1992)
  • C.M. Sherwin et al.

    Social learning influences the food preferences of domestic hens for novel food

    Animal Behaviour

    (2002)
  • B. Sillén-Tullberg

    The significance of coloration per se, independent of background, for predator avoidance of aposematic prey

    Animal Behaviour

    (1985)
  • J. Skelhorn et al.

    Colour biases are more than a question of taste

    Animal Behaviour

    (2008)
  • H.B. Cott

    Adaptive Coloration in Animals

    (1940)
  • M. Edmunds

    Defence in Animals

    (1974)
  • G.J. Fischer et al.

    Color pecking preferences in white leghorn chicks

    Journal of Comparative and Physiological Psychology

    (1975)
  • S.L. Fryday et al.

    The effects of social learning on the food choice of the house sparrow (Passer domesticus)

    Behaviour

    (1994)
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