Pecking preferences and pre-dispositions in domestic chicks: implications for the development of environmental enrichment devices

Environmental enrichment is thought likely to benefit chickens and farmers in many ways; these include reduced fearfulness and feather pecking and imp roved productivity. Enrichment devices would intuitively be more effective if they reliably attracted and sustained appreciable interest but many fail to do so. This may reflect the fact that the choice of stimuli often refle cts availability and human preconceptions rather than a critical considerat ion of the birds' preferences and pre-dispositions. We had previously ident ified string as a particularly attractive pecking stimulus for chicks and a dult hens (Gallus gallus domesticus) of a laying strain (ISA Brown). In the present study we found that chicks of another laying strain (Lohmann Brown ) also pecked sooner and more at a bunch of string than at chains or beads (Experiment 1). White or yellow strings were preferred to led, green or blu e ones (Experiment 2) and white string elicited more pecking than did combi nations of white and yellow or of all five colours (Experiment 3). Varying the length and width of the bunches of string exerted no detectable effects on pecking (Experiment 4) whereas incorporating small, shiny beads in the white string devices actually reduced pecking (Experiment 5). Virtually all the devices elicited progressively more interest with repeated presentatio n; this trend was particularly marked for white string. Collectively, the p resent findings demonstrate that young domestic chicks have clear and speci fic pecking preferences. Although the magnitude of response varied across e xperiments, white string consistently elicited the most interest. Our two m ain conclusions are: (i) white or yellow strings were particularly attracti ve stimuli that drew increasing interest, at least in the short term, and ( ii) simple devices were preferred to more complex ones, or at least to thos e used hen. (C) 2000 Elsevier Science B.V. All rights reserved.