A large pigeon with greenish-brown upperparts, gray head, and gray underparts. Occurs in small flocks that feed on fruits and berries in the canopy. Found only in the evergreen forests of the Nicobar Islands. Similar to Green Imperial-Pigeon, but the Nicobar Imperial-Pigeon is darker above and grayer below, with a brown vent. Calls include burbling notes and a deep, low growl.