Colorfu Hummingbirds Are Among The World's Most Popular Birds

Colorful, combative, and energetic, hummingbirds are among the world's most popular birds. They are found only in the New World. People across North America attract them to their homes through hummingbird feeders and flowering gardens, and can be rewarded with bright migratory species, such as a male Rufous Hummingbird (left). Yet the true center of trochilid diversity is in the Neotropics, home to a dazzling array of species that range from tiny to surprisingly large, and with an assortment of head plumes, tail streamers, and bill shapes.

Their ability to hover and fly backwards makes them unique. Further, their interdependence on and co-evolution with flowers provide a fascinating correlation and field for study. Because the sources of nectar are constantly changing as flowers bloom and fade, most hummingbirds live solitary lives, aggressively defending nectar sources from rivals.

Despite the strong pressure to gather nectar rapidly, studies have shown that 70% of a hummer's time is spent doing little else than singing, self-preening, and sunbathing (Schuchmann 1999). In the two shots below, a male White-necked Jacobin sits near its favored feeder in Trinidad (below left) but immediately reacts when a White-chested Emerald tries to approach. Such interactions can lead to dramatic interspecific aerial chases.

Despite the many species of hummingbirds, they are divided into just two subfamilies (Schuchmann 1999). The Trochilinae include all the colorful species (nearly 300 in all) while the Phaethornithinae is composed of the six genera and 34 species of hermits. Brown, long-tailed hermits forage in the understory; some short-tailed species weigh only 1.6 gram (the same weight as the tiny Bee Hummingbird Mellisuga helenae of Cuba, often termed the "world's smallest bird").

All hermits that have been studied display in noisy leks, their clicking dominating a patch of jungle. Hermits often have a species affinity for Heliconia plants and it can be rewarding to "stake-out" a patch inside the forest. This Rufous-breasted (or Hairy) Hermit (right) was sitting right next to 'his' Heliconia. Unlike many other hummingbirds, hermits are generally not territorial and few species have iridescence. When present, it is limited to the throat or crown. Nonetheless, it is obvious that hermits are hummingbirds, and even the most jaded "I can't tell one bird from another" non-naturalist can identify a hummingbird as such.

The flight mechanisms of hummingbirds allow them to hover almost indefinitely and scientists have wondered for ages about how the bird is able to move so quickly, like an insect, but still has the body structure of a bird.  Researchers have believed for decades that hummingbirds used the same flight mechanisms as insects; but studies conducted within the past decade have proven that hummingbirds have their own unique flight characteristics, different from insects or other birds.

A hummingbird must compete with the force of gravity, which pushes down on the bird.  By flapping its wings, the hummingbird is able to create lift (which pushes the bird upward) and thrust (which helps the bird maintain forward movement).  Drag is the force that conflicts with thrust, air resistance or friction slows down thrust.

Although the hummingbird's flight mechanisms have been compared to those of insects, the hummingbird has all the capabilities and limitations that birds have.  An insect has wings that are almost flat and they gain their lift to fly using two mirror image half strokes, moving their wings back and forth in a figure eight pattern.  This allows the insect to produce nearly equal lift on thier up stroke and down stroke.

A bird however, produces virtually all of its flying lift on the downstroke.A hummingbird is unique in the fact that it can produce 25% of its weight support during its up stroke and 75% of its weight support during the down stroke.