Feather pecking and foraging uncorrelated - the redirection hypothesis revisited.

ABSTRACT

1. Feather pecking (FP) is said to be a redirection of food-related foraging pecks to feathers. The effects of three foraging enrichments on the pecking behaviours of layer pullets in pens and as hens in cages (Gallus gallus domesticus) were studied.2. Treatments included no added enrichment (Control), addition of a mix of wheat and sorghum grains (Grain), a mix of wheat and sorghum grains with lucerne and oaten chaff (Chaff), and lucerne hay (Hay). In pens, Hay was provided in racks, while Grain and Chaff were scattered on the floor. In cages, all treatments were provided in racks. It was predicted that enrichments that encouraged more pecking activity would be most successful at reducing FP.3. Overall pecking activity was similar between all treatments. The Chaff groups tended to FP less than Grain groups, and Hay groups had the least FP. In cages, both Chaff and Hay groups had significantly less FP than either the Grain or Control groups. FP did not reflect stimulus peck rates. Although Chaff groups pecked at their rack significantly less than either Grain or Hay groups, their FP was on a par with the birds in the Hay groups. Feather quality followed these trends.4. The fact that these results were inconsistent with the original hypothesis led to a proposal for a modified hypothesis. Rather than the appetitive component of food searching motivation being redirected to feathers, it is the appetitive component of exploratory motivation, and the ability to reach the goal to update information about the environment is what feeds back to the motivation which leads to FP. This modified hypothesis is consistent with the results of this and many other studies and with modern concepts of motivation, foraging, exploration and food selection.