The bold, assertive personality of this 4 ¼-inch hummingbird makes it a garden favorite among the people who live within its restricted U.S. range in southern Texas. Strikingly different from any other bird, the buffbellies wear bronze-green feathers on its back and emerald-green feathers on its throat. The long chestnut tail is often fanned to create the illusion of great size. The long, coral-red bill is tipped with black.

Buff-bellied hummingbirds have not been as intensively studied as most other hummingbirds that nest in North America. An amazing vocal repertoire includes a complex song replete with trills and cascades as well as several distinctive call notes. The most familiar call is a chatter that sounds like electric static.

The song is given only during the breeding season, which might span April to November. It is often accompanied by a powerful "J"-shaped dive. Males permit eligible females to feed within their territories, but other males are pursued with tremendous vigor.

The nest can be in a variety of trees or shrubs, usually only three to eight feet from the ground. Anacahuita, hackberry, and willow are frequent choices. It is composed of vegetable fibers, thistle down, and a substance that resembles cattle hair. Shreds of bark, light colored lichens, and flower petals decorate the exterior.

Buffbellies are not as strongly migratory as more northerly breeding species. Nevertheless, the bulk of the population moves south into coastal Mexico when nesting is done. For some unknown reason, a portion of them moves northward to spend the winter along the upper Gulf Coast.