Hummingbird

Over four hundred species of hummingbirds have been identified in North and South America, forming the Western Hemisphere’s second largest family of birds. These exceptionally small birds have the greatest comparative energy output of any warm-blooded animal. In one day, they often consume more than half their total weight in food and twice their weight in water. The smaller species have the fastest wing beat of all birds. Unlike other birds, their wing upstroke is as powerful as their downstroke. They can fly forward, backward, and briefly, upside down. The range of the hummingbird stretches from Alaska to Tierra del Fuego, Chile. Because of a constant supply of nectar and insects, tropical hummingbirds rarely migrate. Those hummingbirds that do migrate sometimes travel enormous distances. The rufous hummingbird flies over two thousand miles fromits winterhomein Mexico to the Pacific Northwest and Alaska.

Physical Characteristics of Hummingbirds
Hummingbirds are extremely small, weighing from two to twenty grams. The bee hummingbird is the world’s smallest bird. Their long, slender bills, which are often slightly decurved, and their long bitubular tongues give them easy access to flower nectar, their main source of food. Although their feather structure is among the most specialized of birds, hummingbirds have the fewest feathers. The primary flight feathers decrease in size from the outer feathers inward toward the secondary feathers. Hummingbirds are able to rotate each of their wings in a circle. To hover, they move forward and backward in a repeated figure eight. They can move in any direction instantaneously. Their feet, which are more suited for perching than walking, have three toes directed forward and one pointed back. Hummingbird feathers are iridescent. Depending on the viewing angle, the colors will change from red to gold or from green to turquoise. Adult males have the most intensely colored feathers and in full sunlight seem to glow. Some feathers are also modified to produce sound, so that as the birds fly, a soft humming sound is heard.

Reproductive Biology and Behavior
Hormonal changes prompt the female hummingbirds to begin nest building as ova ripen in their ovaries. In the male, hormonal changes enlarge their testes to many times their normal weight. Following mating, the female takes from one day to two weeks to complete building her nest, and soon after, she lays her eggs. Most hummingbirds lay two eggs, two days apart. The tiny, elliptical white eggs weigh less than 0.02 ounce. Depending on the species, incubation lasts fifteen to twenty days. Newly hatched hummers are featherless and do not open their eyes for two weeks. By two and a half weeks they are covered with feathers and can groom themselves. After testing their wings, at three weeks they are able to leave the nest, although the mother continues feeding them for two to four more weeks. Hummingbirds are highly territorial. Particularly when they are migrating, they aggressively protect their sources of nectar. A nesting female will attack any interloper approaching her nest. Hummingbirds have adapted to living in diverse areas. Like most birds, hummingbirds eat vast quantities of food. They have taste receptors on their tongues and salivary glands, and prefer flower nectars with a high sugar content. Throughout the day, hummingbirds eat frequently. At night, in order to conserve energy, they enter a state of torpor, which is a short-term form of hibernation. In this state they are unable to flee from predators. To resume a normal state requires enough energy to warm their organs and tissues. The birds need to monitor their energy reserves so they can recover from their torpid state.