Free-ranging chickens are social animals. In these groups hens and chicks are the core, while roosters live independently. Social maturity occurs at ~1 yr of age, although most chickens are sent to slaughter prior to this age. Free-ranging chickens show more aggressive behaviors than battery chickens do. Rank is based on multiple factors (eg, size, age, color, and social environment). A new or foreign chicken is lower in rank than a chicken on home ground. Both nesting and food intake are genetically controlled behaviors, and chickens are selected for high food intake. Hens will form nests if supplied with nesting material. An adult chicken that has never used a nesting box will use one if provided.
Last full review/revision April 2012 by Gary Landsberg, BSc, DVM, MRCVS, DACVB, DECVBM-CA; Sagi Denenberg, DVM