Bushy-crested Jays forage both in trees and shrubs, and on the ground. The diet includes insects, seeds, and fruits such as figs (Goodwin 1976). Bushy-crested Jays are also known to follow army ants for hours in order to eat the insects flushed by such swarms (Hardy 1974a). When foraging at ants, jays typically perch 1-2 m above the swarm, fly down to snatch their prey, and return to their perch quickly (Hardy 1974a). Unlike other species that follow ant swarms, these jays typically are silent during feeding (Hardy 1974a). This behavior is not limited to adults (Hardy 1974a).
Cyanocorax melanocyaneus is suspected of being a nest predator (Komar and Thurber 2003). The hummingbird Green Violetear (Colibri thalassinus) were observed to react defensively, craning and looking around nervously, when a Bushy-crested Jay approached the nest; this is the same reaction elicited by the Blue-and-white Mockingbird (Melanotis hypoleucus), a known nest predator (Komar and Thurber 2003).