Chicken, Breed and Domesticated
Chicken is the world’s most numerous domesticated bird, with more than 66 billion farmed worldwide in 2012. These birds have fascinated scholars and researchers since the dawn of Western civilization, and recent studies are beginning to reveal the depths of their complexity and cognitive ability.
According to Andrew F. Fraser, professor of veterinary surgery at Memorial University of Newfoundland, and Donald M. Broom, professor of animal welfare at University of Cambridge: “Those who have studied the behaviour of the domestic fowl in detail…, especially those who have looked at feral fowl…, inevitably acquire much respect for the members of this species.”
Charles Darwin proposed that domestic chickens descended from the Red Jungle Fowl (Gallus gallus), who are indigenous to parts of India and Southeast Asia. Taxonomically, in fact, domestic chickens and Red Jungle Fowl are considered the same species (Gallus gallus). Domestication likely began in Asia, India and China approximately 8,000 years ago and geographically expanded along with trade to the countries of the Mediterranean region. Spanish explorers brought domestic fowl to the New World during the 16th century CE.
Red Jungle Fowl inhabit second-growth forest areas, especially those that have been cleared by burning for agricultural use. Both chickens and jungle fowl are capable of short-distance flight, but they primarily travel by foot11 and prefer areas with dense vegetation for ground cover. The colors of their plumage make them well-camouflaged among the red and brown leaves that collect on the forest floor. Jungle fowl usually segregate into small groups with one male and several females,13 occupying a regular home range,14 or territory during the breeding season. Within their home range they have regular roosting sites, where they sleep high in the trees at night and rest during the hottest part of the day.
The flock’s activities are highly synchronized and consist of regular daily movements within the home range.18,19 As natural water sources are essential for nourishment, the two loci of the jungle fowl’s habitat are the roosting site and the water hole, which is shared with other animals in the area, including other jungle fowl flocks.20 They also make use of tree hollows, where rain water accumulates and where they can find insects under the moist, decaying matter.
Feral chickens (domesticated birds that have reverted to a wild state) have been observed to eat a wide variety of plant matter, including berries, seeds, and grasses, availing themselves of all food sources in their habitats. They scratch the forest floor for insects and snails, and they snatch figs and other fruits from the trees. Feral chickens have even been observed forming symbiotic relationships with cattle, by pecking at the flies that swarm around
the cows’ faces and by scavenging on their waste. Feral domestic fowl have also been observed to eat carrion.
In one study of feral chickens released on an island nature reserve, grasses and oats were the primary component of the diet. Young chicks consumed significantly more invertebrates than adults, for whom plant matter is the most important part of the diet. Chickens are also known to eat stones, sand, and fine grit, some of which are retained in the gizzard and help to grind food during digestion.