-i- AGGRESSIVE BEHAVIOR OF CHICKENS: SOME EFFECTS OF SOCIAL AND PHYSICAL ENVIRONMENTS*

Poultry management experts think in terms of tens or hundreds of thousands of birds. They usually prefer systems which require a skilled mechanic as much as a poultry caretaker. As a result, chickens are often seen as some sort of odd little machine that has feathers, squawks, and struggles if caught. This loss of contact between the caretaker and his charges is often associated with lackof recognition of behavioral and other problems. Breeders and managers know that chickens function well or poorly depending on both genetic constitution and quality of environment. We also know that most widely-used housing environments for laying-type chickens impose some stress, particularly those involving crowded multiple-hen or "colony" cages. We found genotype by housing-environment interactions in each of 3 studies where genetic strains and housing environments varied over a wide range (5,8,12). There appears to be a need to adapt strains of egg-type chickens to specific housing environments. Such adaptation is likely to include behavioral changes or reductions in responsiveness to stimuli that would otherwise cause behavioral stress.