The Mariana Crow is a small black crow with a slight greenish-black gloss on its head, back, underparts, and wings. Its tail has a bluish-black gloss.
Females are smaller than the males.
The Mariana Crow is also known as the aga in Chamorro, one of the native languages of the Mariana Islands. This crow prefers native limestone forest for breeding and foraging, but it will forage in other habitats such as beach strand vegetation and coconut groves. This species is an omnivorous, opportunistic feeder that is known to feed on insects, lizards, bird eggs, hermit crabs, fruits, and seeds. The remnant population on Guam is restricted in distribution to the northern end of the island, where it most frequently nests in two canopy-emergent tree species, Elaeocarpus joga and Ficus prolixa . The population on Rota is distributed islandwide, where it has been found to nest in 18 native genera, most of which are subcanopy in height.