The grey-headed chachalaca is a medium-sized bird, similar in general appearance to turkeys, with a small head, long strong legs, and a long broad tail. They are 48 to 58 cm (1.6 to 1.9 ft) long and weigh 490 to 540 g (1.1 to 1.2 lb). They have fairly dull plumage, grayish brown above and paler below. The head is dark grey with a red dewlap and the blackish tail is tipped with buff. Their primary flight feathers are bright chestnut. Juveniles are browner overall, especially on the head.
The grey-headed chachalaca is found from Mosquitia in eastern Honduras through eastern Nicaragua and most of Costa Rica and Panama into Colombia's Chocó Department. In addition to mainland Panama it occurs on Isla del Rey, where it might have been introduced by native Americans. It inhabits a variety of humid landscapes characterized by dense vegetation such as thickets, secondary forest, brushy abandoned fields, and thinned forests. It shuns the interior of dense forest though it can occur in their edges. In elevation it ranges from sea level to 1,700 m (5,600 ft).
The grey-headed chachalaca forages typically in groups of six to 12 but sometimes up to 20, usually in the vegetation but sometimes on the ground. Its diet is about 75% fruit, 17% leaves, and 8% invertebrates. In the dry season it visits rivers to drink in the morning and evening.