The Red Junglefowl (Gallus gallus) is a tropical member of the pheasant family. It is thought to be ancestral to the domestic chicken, with some hybridisation with the Grey Junglefowl. The Red Junglefowl was first domesticated at least five thousand years ago in Asia, then taken around the world, and the domestic form is kept globally as a very productive food source of both meat and eggs.
The range of the wild form stretches from Tamil Nadu, South India (where it has almost certainly been diluted with cross breeding from domestic breeds) eastwards across southern China and into Malaysia, The Philippines (where it is locally known as labuyo) and Indonesia. Junglefowl are established on several of the Hawaiian Islands, but these are feral descendents of domestic chickens. They can also be found on Christmas Island and the Marianas.
Each of these various regions had its own subspecies. Some examples include:
- G. g. gallus Indochina
- G. g. bankiva Java
- G. g. jabouillei Vietnam
- G. g. murghi India
- G. g. spadiceus Burma
- G. g. domesticus (Chicken)
Male and female birds show very strong sexual dimorphism. Males are much larger; they have large red fleshy wattles and comb on the head and long, bright gold and bronze feathers forming a "shawl" or "cape" over the back of the bird from the neck to the lower back. The tail is composed of long, arching feathers that initially look black but shimmer with blue, purple and green in good light. The female's plumage is typical of this family of birds in being cryptic and having evolved for camouflage as she alone looks after the eggs and chicks. She also has no fleshy wattles or comb on the head.
During their mating season, the male birds announce their presence with the well known "cock-a-doodle-doo" call or crowing. This serves both to attract potential mates and to make other male birds in the area aware of the risk of fighting a breeding competitor. A spur on the lower leg just behind and above the foot serves in such fighting. Their call structure is complex and they have distinctive alarm calls for aerial and ground predators to which others react appropriately.
Males make a food-related display called 'tidbitting', performed upon finding food in the presence of a female. The display is composed of coaxing, cluck-like calls and eye-catching bobbing and twitching motions of the head and neck. During the performance, the male repeatedly picks up and drops the food item with his beak. The display usually ends when the hen takes the food item either from the ground or directly from the male’s beak and is associated with copulations and more offspring. Males that produce anti-predator alarm calls appear to be preferred by females.
They are omnivorous and feed on insects, seeds and fruits including those that are cultivated such as those of the oil palm.
Flight in these birds is almost purely confined to reaching their roosting areas at sunset in trees or any other high and relatively safe places free from ground predators, and for escape from immediate danger through the day.
In July 2012, Dr Alice Storey et al announced a study using mitochondrial DNA recovered from ancient bones from Europe, Thailand, the Pacific and Chile, and from Spanish colonial sites in Florida and the Dominican Republic, in directly dated samples originating in Europe at 1000 B.P. and in the Pacific at 3000 B.P. The study showed that chickens were likely domesticated from wild Red Junglefowl, though some have suggested possible genetic contributions from other Junglefowl species. Domestication occurred at least 5,400 years ago from a common ancestor flock in the bird's natural range, then proceeded in waves both east and west. The paper also states that the earliest undisputed domestic chicken remains are bones associated with a date of approximately 5400 BC from the Chishan site, in the Hebei province of China. In the Ganges region of India, Red Junglefowl were being used by humans as early as 7,000 years ago. No domestic chickens older than 4,000 years have been identified in the Indus Valley, and the antiquity of chickens recovered from excavations at Mohenjodaro is still debated. 
The other three members of the genus — Sri Lanka Junglefowl (Gallus lafayetii), Grey Junglefowl (Gallus sonneratii), and the Green Junglefowl (Gallus varius) — do not usually produce fertile hybrids with the Red Junglefowl, suggesting that it is the sole ancestor of the domestic chicken. However, recent research has revealed the absence of the yellow skin gene in the wild Red Junglefowl found in domestic birds, which suggests hybridisation with the Grey Junglefowl during the domestication of the species. A culturally significant hybrid between the Red Junglefowl and the Green Junglefowl in Indonesia is known as the Bekisar.
Purebred Red Junglefowl are thought to be facing a serious threat of extinction because of hybridization at the edge of forests where domesticated free ranging chickens are common.
- Eriksson, Jonas; Larson, Greger; Gunnarsson, Ulrika; Bed'hom, Bertrand; Tixier-Boichard, Michele; Strömstedt, Lina; Wright, Dominic; Eriksson J, Larson G, Gunnarsson U, Bed'hom B, Tixier-Boichard M, et al et al. (23 January 2008), "Identification of the Yellow Skin Gene Reveals a Hybrid Origin of the Domestic Chicken", PLoS Genetics (PLoS Genet), preprint: e10, doi:10.1371/journal.pgen.1000010.eor
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- Ancestors of chickens studied for conservation; 7 Aug, 2008; The Economic Times, Times of India