Northern Emerald-Toucanet is a small toucan of humid montane forests of Central America; it is the northernmost species of toucan, occurring north to eastern Mexico. Like other species of Aulacorhynchus, it is primarily bright green, with a white or blue throat, and rufous undertail coverts and rufous tips to the rectrices. This species is quite variable geographically, containing as many as eight subspecies. The subspecies differ subtly in size, and more dramatically in the color of the throat (white or blue) and the pattern of the bill. The bill is black and yellow. The mandible always is black, and the maxilla is mostly yellow, but the extent of the yellow varies across subspecies. Northern Emerald-Toucanet typically forages on fruit and small vertebrates in humid forest, frequently moving together in small flocks. As is typical of toucans, this species nests in cavities in trees. The clutch size usually is three to four eggs, and both sexes incubate and feed the nestlings. Northern Emerald-Toucanet is the best known species of Aulacorhynchus, although most of what is known about its biology is based on observations in Costa Rica.