The Green-crowned Brilliant is nectarivorous, often visiting the inflorescences of Marcgravia vines, large plants of which are intermittently defended by males, while females also visit understory flowers, such as those of Drymonia conchocalyx (Stiles and Skutch 1989). The species also feeds at flowers of Cephalis, Ericaceae and Gesneriaceae (Restall et al. 2006). In addition, it frequently visits Heliconia flowers whose nectar it can access with its straight bill (Stiles and Skutch 1989, Restall et al. 2006, Taylor and White 2007). The results of research on the pollen loads carried by hummingbirds in an area of southwestern Costa Rica suggested that this species may become a specialized feeder during the dry season (Borgella et al. 2001). It also takes flies, wasps and other flying insects in mid-air and gleans tiny insects and spiders from foliage (Restall et al. 2006).