At a distance, the Marbled Wood-Quail appears to be mostly dark brown. Close at hand, the plumage is variegated with browns and buffs of a variety of shades, and flecked with black. The breast and abdomen are finely and irregularly barred with buff or cinnamon-brown blackish. There is an erectile crest of long, deep brown feathers on top of the head. The lores and region around the eyes are bare of feathers, and the skin is a bright orange-red. The male is slightly larger than the female, and both sexes have dark eyes, blackish bills, and dark gray toes and legs (Skutch 1947).
The Marbled Wood-Quail is the only wood-quail with bare orange to red facial skin and otherwise more or less uniform plumage. The Starred Wood-Quail (Odontophorus stellatus), the distribution of which broadly overlaps with that of Marbled Wood-Quail in western Amazonia, has rufous, not brown, underparts. The Starred Wood-Quail with white spots on the breast (which may be difficult to see in the forest understory), and a rufous crown that contrasts with a gray throat, and sides of the head and neck.
Wood-quail are the size and color of several species of small forest tinamous (Crypturellus), but none of these are finely barred throughout. Also note the different shape: tinamous are small-headed, have longer, thinner necks, and appear tailless (Hilty and Brown 1986).
The following description is based on Blake (1977):
Adult: Sexes similar. Plumage variable. The crown and short crest are reddish brown or sooty, sometimes finely barred. The sides of the head are dull chestnut, rufous, or gray, this color sometimes extending down across the throat. Back of the neck and upper back brown or gray, finely barred black. Lower back, rump, and uppertail coverts paler, somewhat olive or tawny. Wing coverts and scapulars brown or grayish, barred and spotted with buff and black. Flight feathers fuscous, barred with buff on outer webs. Underparts mostly gray, brown or tawny, and often narrowly barred (sometimes spotted) with black and white.
Juvenile: Same as adult but has slightly less vermiculation (Carroll 1994).
Chick: "After hatching, chicks are tiny, chubby, and covered with black and buff down. The top of the head and back are blackish, with a narrow white line along either side of the back, and the cheeks and sides of the neck are buff" (Skutch 1947).
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Iris: Hazel or brown.
Orbital skin: Vermilion or orange.
Bill: Bluish black or dusky gray; orange-red in juveniles (Carroll 1994).
Tarsi and toes: Bluish lead or gray.
Data from Blake (1977).
Total length: 24-29 cm (Blake 1977), 25 cm (Stiles and Skutch 1989), 25.5-28 cm (Ridgely and Greenfield 2001), 28 cm (Hilty 2003)
Linear measurements (mm) of Odontophorus gujanensis gujanensis (Blake 1977)
| || || wing (chord)|| tail|| culmen from base|
| adult|| mean|| 141.1|| 66.6|| 20.6|
| (sexes combined)|| range (n=20)|| 130-150|| 61-74|| 19-24|
Mass: male, mean 331 g (range 313-349 g, n=3); female, 298 g (n=1). Data from Haverschmidt and Mees (1994)