Responses of domestic chicks to selected pecking devices presented for varying durations

Environmental enrichment and/or pecking devices for chickens would intuitively be more effective if they attracted and sustained appreciable interest. The present study was designed to determine which of three classes of stimuli (colour-matched (white, yellow and green) bunches of string, baubles or leg bands) elicited the greatest interest by pair-housed domestic chicks of a laying strain. These `pecking devices' were introduced simultaneously into the chicks' home cages for various durations and at different stages of development. The chicks consistently pecked the string sooner and more often and spent longer near it than either of the other stimuli. Such differential responsiveness was observed regardless of whether the chicks received the devices at 2 days of age for 6 h/day for 10 consecutive days (Experiment 1), continuously (Experiment 2), or for 20 min/day (Experiment 3). String also elicited more interest than the other devices even when exposure was delayed until the chicks were 10 days old (Experiment 4). Scan sampling (Experiments 1 and 2) and focal bird observations (Experiments 3 and 4) yielded similar findings but the latter technique provided more informative indications of preference. The lower levels of pecking found when stimuli were first introduced at 10 days of age probably reflect a more pronounced neophobic reaction to the devices in the older birds rather than a lack of interest. Encouragingly, not only was there no evidence of habituation in any of these experiments but the chicks showed progressively more interest in the string, even when they were exposed to it continuously for 10 days. Although none of the devices elicited particularly high rates of pecking, the consistently greater interest shown in string was encouraging. Collectively, our studies suggest that string may be an attractive and practicable stimulus that affords chickens the opportunity to exercise a behaviour fundamental to their nature.