Almost all information on the diet of Yellow-throated Toucan refers to swainsonii. These toucans are largely frugivorous. Being generalists, they eat from a wide variety of fruiting trees and play a vital role in seed dispersal. Preferred food sources include Virola, Casearia, Cecropia, Protium, Hampea, and Trophis spp. (Howe 1977, 2004; Skutch 1980). Virolas are especially important food sources for Yellow-throated Toucans. For example, 43% of V. sebifora fruit eaten by birds is consumed by this toucan (Howe 1981). Casearia corymbosa is also a vital food source for toucans since it fruits throughout months when very little else is available. Howe (1977) observed Yellow-throated Toucans feeding extensively on Casearia during Costa Rica’s early dry season, but noticed virtual abandonment when other fruits (Virola and Protium) came into season.
Yellow-throated Toucans also sometimes take lizards, large insects, and the eggs and young of other birds. Insect prey includes cicadas and walking sticks (Howe 1977). They have also been recorded attempting to chase and snatch flying termites out of the air (Skutch 1972, Short and Horne 2001). Mindell and Black (1984) observed a pair of toucans cooperatively hunt and consume a small lizard (see Behavior). Yellow-throated Toucans also raid the nests of Social Flycatchers (Myiozetetes similis), Tropical Kingbirds (Tyrannus melancholicus), Boat-billed Flycatchers (Megarynchus pitangua), Collared Araçaris (Pteroglossus torquatus), and some woodpeckers (Picidae) (Skutch 1972, Short and Horne 2001). One toucan even drove a Double-toothed Kite (Harpagus bidentatus) from its nest and ate one of the eggs (Laughlin 1952).
Despite what may seem like a voracious appetite for meat, animal matter only makes up a tiny portion of the diet of Yellow-throated Toucan. Adult birds eat over 90% fruit and are thought to mainly catch prey for their young (which require extra protein for growth). In one study that analyzed stomach contents, none of the six Yellow-throated Toucan stomachs examined held any animal matter whatsoever (Remsen et al. 1993).