One of three members of the genus Amazilia that occur at least somewhat regularly north of Mexico, the Buff-bellied Hummingbird is found in a variety of habitats from arid shrublands to semihumid woodlands of the Gulf Coast of Mexico, south to Guatemala and north to southern Texas. In the United States, this species is known to breed only in areas of southern coastal Texas, where it is common between March and August, becoming rare during fall and winter, when it apparently disperses south to Mexico and northeastward to areas of the southeastern United States.
This is probably the least-studied hummingbird that occurs regularly in the United States, reflecting its limited distribution here and its absence from western Mexico, where several detailed studies of other hummingbirds have been made. In recent years, confirmed nesting records of this species from southern Texas have been few (Chavez-Ramirez 2001); most information available on its breeding biology was recorded in earlier works from ne. Mexico (Bendire 1895, Bent 1940a, Sutton and Burleigh 1940b, Sutton and Pettingill 1942a). In addition, there is insufficient historical information to evaluate the current status of this hummingbird or any trends in its population levels. Its northward movements in fall and winter are unique among North American hummingbirds—an interesting biological phenomenon that warrants further investigation.