What’s in a peck? Using fixed action pattern morphology to identify the motivational basis of abnormal feather-pecking behaviour
Publication Type: |
Journal Article |
Year of Publication: |
2008 |
Authors: |
L. M. Dixon, I. J. H. Duncan, G. Mason |
Publication/Journal: |
Animal Behaviour |
Keywords: |
chicken, dustbathing, feather pecking, fixed action patterns, foraging, gallus gallus, motivation, welfare |
ISBN: |
0003-3472 |
Abstract:
Like many captive animals, hens, Gallus gallus, used for agricultural production perform abnormal behaviours. They are particularly prone to feather pecking, the severest form of which involves the pecking at and removal of feathers, which can cause bleeding and even stimulate cannibalism. The two main hypothesized explanations for feather pecking concern frustrated motivations to forage or, alternatively, to dustbathe, leading to redirected behaviour in the form of pecks at plumage. Previous work on pigeons has shown that the detailed morphology of pecks involved in drinking and feeding, or in working for food or water, involves motivationally distinct [`]fixed action patterns’. We therefore used methods similar to these fixed action pattern studies to quantify the motor patterns involved in foraging and in dustbathing pecks, for comparison to feather pecking. We videoed 60 chickens pecking at a variety of forages and dustbaths, along with novel objects, water and bird models that could be feather pecked. We recorded the durations of the head fixation before the peck, between the head fixation to beak contact with each stimulus and of the whole peck sequence. We used mixed models to assess whether the motivation underlying a peck affected its morphology and whether severe feather pecks resembled or differed from either dustbath or foraging pecks (or even novel-object pecking or drinking). The motor patterns involved in pecks at forages, dustbaths, novel objects and water all varied significantly; importantly, the motor patterns involved in pecking during dustbathing and foraging differed (P < 0.0001 for all measures). Severe feather pecks proved similar to foraging pecks (NSD: power > 0.95) but different from all other pecks, including dustbathing (P < 0.0001 for all measures). These results indicate that severe feather pecking derives from frustrated motivations to forage, not to dustbathe. More broadly, they suggest that finely analysing fixed action pattern morphology can help elucidate the motivational bases of puzzling abnormal behaviours in captive animals.