Drills are good climbers and will readily climb to get fruit, which may be high in the trees. They will usually sleep at night on low branches of trees. They walk on all fours, using the flat surfaces of the foot and hands, not the knuckles as apes do. Drills live in family troops of about 20 or more animals. There is one dominant male per troop, who dominates until a challenge from another mature male is successful.
Grooming is an important part of socializing, as well as keeping individuals parasite free.
It also reinforces hierarchy of the group. Habitat Monas are very adaptable and live in a variety of habitats, including secondary rain forests, mangrove swamps, gallery forests, and woodland areas. Monas are sometimes found in farmlands such as cacao plantations and gardens. They prefer to live in the tops of trees but can be seen in the mid-level and lower canopies. Diet Monas have cheek pouches for storing their food.