Thanks to thousands of years spent living in close proximity to humans, domestic chickens (Gallus gallus domesticus) utilize farms and backyards as their natural habitat. However, the species from which they likely originated, range throughout various habitats -- especially areas of secondary growth -- of south Asia. To ensure your domestic pets remain healthy, incorporate the principles of their historic habitats into their home.
The Family Tree
While scientists are relatively sure that chickens first underwent the process of domestication about 7,500 to 10,000 years ago, the exact manner by which this happened remains unclear. Domestic chickens share close kinship with the red jungle fowl (Gallus gallus gallus), but it also appears that the gray jungle fowl (Gallus sonneratii) may have contributed genes to the domestic chicken. Both birds share broadly similar habitat preferences.
In the wild, chickens move between two primary habitat types -- their feeding areas, which typically feature an ample shrub layer and open canopy, and their roosting areas, which they use at night. Wild jungle fowl and their relatives usually roost in the lower branches of trees, which provides them some protection from predators and partially shields them from the elements.
Captive chickens require a similar dual-habitat. They will need a chicken coop, which usually takes the form of a wooden building, and an outdoor area in which they can forage for food. This area is usually enclosed in a fence to contain the birds and keep predators at bay. Provide your birds' food and water in the activity area, as this is where they would find it in the wild.
Suitable Space and Density
Wild chickens do not have to cope with many limits to their movements in their natural habitats, but by the very nature of captivity, chicken keepers must establish boundaries. Like all captive animals, chickens need enough space to complete their natural behaviors and obtain sufficient exercise, but, as they are highly social animals, chickens must have enough space to establish a social hierarchy. This means that while the total amount of space available to the chickens is important, what is equally important is the amount of space provided for each bird.
While they usually exceed commercial poultry regulations, most backyard chicken keepers have success providing at least 10 square feet of outdoor space and 2 square feet of indoor space for large breeds -- small breeds require slightly less space per bird. Cornell University recommends keeping no more than one rooster -- provided that they are legal in your area -- for every 10 hens.
Food and Foraging Strategy
In the wild, jungle fowl consume a varied diet, including grains, grasses, agricultural crops and invertebrates; for the best results, provide a similar diet for your pet chickens. The bulk of your chicken's calories should come in the form of a commercial poultry feed, but allow them to forage for insects, vegetation and seeds, while they are in their activity area. Avoid feeding your pets people foods, as these can be unhealthy for the birds. Additionally, in some locations, it is illegal to offer your chicken foods that have been in your kitchen.