The grey junglefowl, also known as Sonnerat’s junglefowl, is one of the wild ancestors of domestic fowl together with the red junglefowl and other junglefowls.
A gene from the grey junglefowl is responsible for the yellow pigment in the legs and different body parts of all the domesticated chicken.
This species is endemic to India, and even today it is found mainly in peninsular India and towards the northern boundary. It will sometimes hybridize in the wild with the red junglefowl. It also hybridizes readily in captivity and sometimes with free-range domestic fowl kept in habitations close to forests.
The male has a black cape with ochre spots and the body plumage on a grey ground colour is finely patterned. The elongated neck feathers are dark and end in a small, hard, yellowish plate; this peculiar structure making them popular for making high-grade artificial flies. The male has red wattles and combs but not as strongly developed as in the red junglefowl. Legs of males are red and have spurs while the yellow legs of females usually lack spurs. The central tail feathers are long and sickle shaped. Males have an eclipse plumage in which they moult their colourful neck feathers in summer during or after the breeding season.