The Buff-bellied Hummingbird – also known as Fawn-breasted Hummingbird or Yucatan Hummingbird – is a medium-sized hummingbird that grows to a length of 3.9-4.3 inches and a mass of 4-5 grams. The average weight of the male is 4.07 grams and that of the female is 3.67 grams. With this size, the Buff-bellied Hummingbird is considered to be of the largest hummingbirds in the United States.
It is believed to be the least-studied hummingbird that that has regular appearances in the United States.
The adult male Bluff-bellied has a metallic olive green back and crown. It has rusty sides and a cinnamon-buff belly. The tail and primary wings have a rufous color and are slightly forked. It also has a remarkable white lining that surrounds its eyes. The lower chest has a color shift that spans from white to different shades of grey or green, or yellowish-brown (‘buffy’). The bird’s underwing is white.
The adult male’s throat has a metallic golden green coloration, and its straight and very slender bill is reddish in color and has a dark tip.
The female Buff-bellied closely resembles the male, although it has a dark upper less bill and a noticeably less colorful plumage.
The juveniles, on the other hand, are comparably duller than the adults, with greyish or ‘buffy’ throat and chest. Also, they have edged feathers with buff or tawny.
Buff-Bellied Hummingbirds feed on nectars from flowers and flowering trees. They use their long and extendable tongue in doing so.
Also, they catch insects on their wings to supplement their protein requirements. They need protein especially during the breeding season to ensure that their young are properly developed.
They may also stray on local hummingbird feeders for some sugary water.
Distribution and Habitat
The Buff-bellied Hummingbird’s preferred habitat locations are open woodland, second growth, clearings, semi-arid scrub, plantations and gardens, pine-oak forests and thickets along watercourses.
The Buff-bellied Hummingbird is still considered a minor breeding species in the U.S. However, it is seen to be expanding into the coastal states as a result of habitat loss in Mexico. It breeds near the coast of the Gulf of Mexico, from south Texas to Mexico.
On different parts of the year, the species can also be observed in Alabama, Arkansas, Florida, Georgia, Louisiana, Mississippi, South Carolina, and Texas. However, it only breeds in Texas. It is also often seen dispersing to the northeast from its breeding areas in south Texas – a northerly movement that is unique among North American hummingbirds.
The Buff-bellied is partially migratory. During winter, Buff-bellied Hummingbirds would move towards eastern coastal Mexico.
Behavior and Ecology
Both males and females fiercely defend their feeding locations within his or her territory.
The Buff-bellied Hummingbirds are known to have an interesting vocal repertoire that includes a complicated song with trills, cascades, and numerous unique call notes. The most familiar of these sounds is the chatter like electric static.
However, just like the rest of the hummingbird species, Buff-bellied Hummingbirds are solitary for most aspects of their lives. Indeed, the only involvement of the male in the reproductive process is the actual mating with the female. Other than that, they do not live nor migrate in flocks. And there is no bond that is formed between pairs.
The adult male Buff-bellied would exhibit a dive display during courtship by flying in a U-shaped pattern. Both males and females are promiscuous in nature, and may actually mate with different individuals in one season.
The female Buff-bellied builds the nest in a safe location such as a shrub or a tree. The cup-shaped nest is made out of plant fibbers that are woven together. The outside lining of the nest is made of green moss to camouflage the environment. The nest’s structure is strengthened by the use of spider webs and other sticky materials.
The average clutch of the species consists of two white eggs. Upon hatching, the young Buff-bellied Hummingbirds are generally helpless – blind, immobile and without any down. They leave the nest after 7-20 days.
The Buff-bellied Hummingbird’s very large range suggest that the species does not approach the thresholds for vulnerable under the range size criterion. Also, its increasing population trend suggest that it is not approaching the threshold for vulnerable under the population trend criterion.
Over the last 40 years, the Buff-bellied a population spike in North America, which is about 172% increase per decade.
Agriculture has always been cited as a threat to the Buff-bellied Hummingbird’s population in Texas and Mexico, especially that it reduces the breeding habitat of the species. However, the actual effects of these land developments have not yet been recorded.