Aulacorhynchus haematopygus is native to the humid montane forests of the Andes in Colombia, Ecuador, and northern Peru. This toucanet inhabits elevations ranging from approximately 3,300 to 8,500 feet, often favoring the edges of cloud forests, mossy woodlands, and secondary growth. It is a resident bird and does not undertake long-distance migrations. The species is considered fairly common within its range and is currently listed as Least Concern by the IUCN.

This species measures about 12 to 14 inches in length and weighs around 5 to 6 ounces. It is easily identified by its mostly green body, blue-green throat, and distinctive crimson patch on the rump that gives the species its common name. The bill is thick and slightly curved, predominantly black with a pale vertical stripe near the base. Both sexes look similar, though males are slightly larger. Its vocalizations are low, repetitive croaks that can be heard echoing through the forest canopy. The species is omnivorous, feeding primarily on fruit but also supplementing its diet with insects, small reptiles, and bird eggs when available. It often travels in small groups or pairs and participates in mixed-species feeding flocks, moving through the canopy and subcanopy in search of food.

Nesting usually occurs in tree cavities, often those abandoned by woodpeckers. Both male and female contribute to incubation and chick-rearing duties. Photographed in north-western Ecuador.