Body size and fluctuating asymmetry in relation to cannibalistic behaviourin laying hens

We studied cannibalism in laying hens, Gallus gallus domesticus. From farms experiencing high mortality caused by cannibalism we collected cannibalist ic birds, birds with injuries caused by pecking and control birds. All fact ors such as farm, bird hybrid and age were identical within a set of three birds, but differed between trios. Based on predictions from studies on wil d animals, we hypothesized that cannibalistic laying hens would be larger a nd victims smaller than control birds, and that victims would in some way b e less fit than control birds. In addition, since cannibalism in the wild i s usually shown by individuals under adverse conditions, we hypothesized fu rther that under commercial conditions cannibalistic individuals would be t hose that experience the environment as more stressful than others in the f lock. Since fluctuating asymmetry is thought to be positively correlated wi th low stress-buffering capacity, we expected cannibals and victims to be m ore asymmetrical than other birds. As predicted, cannibals were heavier and taller than other birds and both victims and cannibals were more asymmetri cal than control birds. (C) 2001 The Association for the Study of Animal Be haviour.