The grey-bellied comet is a large hummingbird with a long beak and a deeply forked tail, growing to 14 to 17 centimetres (5.5 to 6.7 in).

The bird has been found living in five separate, but close sites in north central Peru in the Andes mountains.

The grey-bellied comet inhabits areas of steep, rocky, and dry slopes with some vegetation.

[3] The grey-bellied comet plays a similar role as other hummingbirds in pollinating woody shrubs and trees.

Human modification to the habitat with agriculture is fragmenting and decreasing the already small portion of land the bird inhabits.