A Mexican endemic, Black-backed Oriole principally breeds above 1500 m on the central plateau; the population shifts slightly farther south in the non-breeding season, when it occurs south to Oaxaca. This species occupies a variety of forest types in arid to semi-humid environments, including riparian groves and pine-oak forests. Black-backed Oriole is insectivorous; its diet is not known in much detail, other than that this oriole is one of the major predators of wintering Monarch Butterflies (Danaus pleixippus) in central Mexico. Monarchs are toxic to most predators, but these orioles apparently circumvents this problem by consuming the internal parts of the butterflies, which are less toxic. In the nonbreeding season, Black-backed Orioles often forages in small flocks, which also may include Bullock's Oriole (Icterus bullockii). Indeed, there is a low level of hybridization between Black-backed and Bullock's orioles where their breeding ranges abut in northern Durango. Males of the two species easily are distinguished: male Black-backed has a mostly black face, and black rump, uppertail coverts, and sides, and the orange of the underparts is yellower than in Bullock's. Female and immature Black-backed Orioles are more similar to comparable plumages of Bullock's, but have duskier heads and sides, reflecting the plumage pattern of the male. Although Black-backed Oriole typically is only a short distance migrant, it very rarely occurs as a vagrant north to the United States.