Black Guans are generally solitary, but are sometimes seen in pairs or groups. Pairs are most often seen during breeding season (Stiles & Skutch 1989). Flocks of Black Guans are most likely family groups (Stiles & Skutch 1989); in Monteverde, Costa Rica, groups of up to seven individuals have been observed (Joyce pers. obs.).
Though Black Guans are mainly arboreal, they will descend to the forest floor to feed (Stiles & Skutch 1989), drink, and bathe (Joyce pers. obs.).