[5] In the revised classification to create monophyletic genera, the violet-crowned hummingbird was one of three species moved to the resurrected genus Leucolia by some taxonomic systems.

[7][8][3] As of that date the Clements taxonomy retains the species in Leucolia and BirdLife International's Handbook of the Birds of the World in the earlier Amazilia.

Their underside from throat to undertail coverts is pure white with light olive green flanks.

The nominate A. v. violiceps is found from extreme eastern and southern Michoacán south into northwestern Oaxaca.

The nominate and the southerly population of ellioti inhabit a variety of landscapes including riparian corridors in thorn scrub, deciduous and pine-oak forest, fields, orchards, and urban and suburban parks and gardens.

[10] The violet-crowned hummingbird's populations in the U.S. and well into Sonora and Chihuahua are mostly migratory, but some individuals have overwintered as far north as Arizona.

The increasing numbers of breeding and non-breeding observations in the U.S. suggest that the species "is best viewed as a wanderer that is expanding its range northward."

From southern Sonora and Chihuahua it is essentially sedentary, though it appears to makes some movements to follow food resources.

[10] The violet-crowned hummingbird forages for nectar while hovering; it feeds from a wide variety of flowering plants and shrubs.