Highly social, Cyanocorax cyanomelas usually moves in groups of 3 to 7 birds, though flocks can reach up to 12 individuals. It is an opportunistic omnivore, feeding on insects, fruits, seeds, small vertebrates, and even leftovers near human settlements.

This species frequently raids the nests of other birds, preying on both chicks and sometimes adults. Despite its aggressive side, it also exhibits cooperative breeding, where members of a group help care for each other’s young.

Cyanocorax cyanomelas has also been observed forming mixed-species flocks, often taking the lead. It uses loud vocalizations to alert others to food or danger. Rare mutualistic behavior has been seen where the jay picks parasites off mammals like tapirs and deer, especially in wooded areas.

Cyanocorax cyanomelas is typically found in scattered forests, gallery woodlands, and open groves. It prefers areas with tall trees, even in open countryside. Its range includes the Brazilian states of Mato Grosso, Minas Gerais, Goiás, Paraná, and São Paulo.

We observed nests in Poconé, Mato Grosso (9 nests).

Breeding usually occurs at the beginning of the rainy season.

The nest is cup-shaped, built with dry twigs of various sizes, and lined with palm fibers, small roots, and plant fragments. Nests are typically placed 3 to 10 meters above the ground, though some have been found as low as 1.5 meters, especially near wetlands.