Do the stereotypies of pigs, chickens and mink reflect adaptive species differences in the control of foraging?
Publication Type: |
Journal Article |
Year of Publication: |
1997 |
Authors: |
G. Mason, M. Mendl |
Publication/Journal: |
Applied Animal Behaviour Science |
Keywords: |
autoshaping, chickens, evolution, feeding behaviour, foraging, mink, motivation, pigs, stereotypies |
ISBN: |
0168-1591 |
Abstract:
The food-related stereotypies of some captive species (e.g. mink) are performed most often prior to feeding, while those of others (e.g. pigs and chickens) occur at low levels before feeding and increase after food consumption. It has been suggested that these differences reflect adaptive species differences in how feeding behaviour is controlled. However, this hypothesis rests on several underlying assumptions for which there is incomplete support. One assumption is that there are indeed species differences in the design of motivational systems, and we suggest some specific predictions to test this idea. For example, the ingestion of small portions of food should lead to greater enhancement of local searching behaviour in species whose food supply is particulate and patchy. The basic premise underlying this evolutionary explanation for species differences in stereotypy is that such differences are genetically based, not an artefact of the way different animals are kept. However, we argue that variation in husbandry may also cause variation in stereotypies. For example, the autoshaping literature reveals factors likely to affect pre-feeding stereotypies: unreliable predictors of food delivery, or predictors that occur some time before food is presented, give rise to general locomotory search phases of appetitive behaviour rather than behaviour related to food handling. Farmed mink may therefore show high levels of pre-feeding locomotor behaviour principally because sounds predicting the delivery of their daily meal are quite unreliable and commence long before the food arrives. Lack of space may also inhibit locomotor forms of pre-feeding stereotypies in pigs and chickens. In addition, the high post-feeding appetitive behaviour of these two species may be caused by lack of satiation following food. Overall, evolutionary hypotheses make predictions about stereotypy based on feeding ecology, but there are also alternative causal hypotheses that make predictions based on aspects of husbandry. Together, these may help to explain the forms of existing stereotypies, and to anticipate the forms likely to arise in new husbandry systems or in newly captive species.