Who hasn’t been amazed by the acrobatic antics of hummingbirds? What stunt flyers! They are able to fly not only forwards, but backwards and even briefly upside-down. They can also hover for extended periods. When heard close-up, the rapid flapping of their wings (about 80 times a second) produces the characteristic humming sound that gives rise to their name.
As a group, they are the smallest birds known. They lead very high pressure lives, with astonishing metabolic rates and huge hearts (in comparison with their body weight) which have to pound more than 1200 times a minute when the bird is active. To support these extreme expenditures of energy, hummers eat about half their own weight in sugar each day, mostly from frequent meals of flowers’ nectar though they also like small insects and mites. To put their eating requirements into perspective, a human equivalent would have to eat about 130 kg (285 pounds) of hamburger meat each and every day!
Fortunately, hummingbirds’ metabolic rates and body temperatures drop at night, allowing them to sleep without starving to death. In extreme circumstances, if resources are scarce, hummers go into torpor (stagnation) for up to 14 hours to conserve their last remaining reserves of energy.
Not surprisingly, the world’s smallest birds lay the world’s smallest birds’ eggs, two at a time, in a tiny, beautifully constructed nest of mosses, lichens, cobwebs and other fine material, often difficult to distinguish from the leaves or twigs supporting it.
Hundreds of kinds
Individual hummers can be frustratingly difficult to identify. Worldwide, there are more than 320 different species of hummers, all of which belong to the Trochilidae family. None are found outside the Americas; many are confined to the American tropics.
Females and juveniles generally have less distinguishing color than adult males of the same species. Most males have brilliantly iridescent throat patches (gorgets) which reflect the light in a dazzling display of bright blue, green or red. However, the colors seen depend in great part on the angle of the light. Colors also vary depending on habitat. Forest-dwelling species (hermit hummingbirds), which live in darker, less colorful, surroundings, are more drab than residents of open-country.
Mexico’s 50 different species include several seen seasonally in the southern U.S. Many hummingbirds are migratory. The ruby-throated hummingbird prepares for its annual 800km non-stop flight across the Gulf of Mexico, by an intense pre-flight eating binge which increases its body weight by about 50%.
Hummingbirds are such voracious feeders that they are major pollinators, accidentally carrying pollen from one flower to another on their rounds. They can also be fiercely territorial, defending their favorite restaurants against all other birds, including other members of the same species. Their long bills reach nectar from even the deepest, least accessible tubular flowers. Unable, so far as we know, to recognize food by smell, they scour brightly-colored red, orange and yellow flowers, though their eating habits are by no means restricted to these colors.
Many tropical species in the Musaceae family (which includes bananas and bird-of-paradise) have some flowers which contain virtually no nectar, while others are richly endowed. Hummingbirds are unable to tell which flowers are worth exploring and which not, so the plants are guaranteed cross-pollination as the birds have to visit numerous flowers in order to obtain sufficient nectar.
Travel by nose
Animals can also benefit from hummingbirds. The hummingbird flower mite, for example, takes advantage of hungry hummingbirds to move from one flower to the next. As the hummer greedily consumes nectar, the mite climbs quickly into the bird’s nostril, skipping off again at the next stop.
Pre-Columbian ideas about hummers
Indigenous Mexicans regarded their acrobatic hummingbird friends with a certain awe. In the Magliabecchiano codex (dating from the mid-sixteenth century and now in Florence, Italy) an Indian artist depicts the god, Quetzalcoatl with a feathered headdress. Feeding at a tubular blossom protruding out of the headdress is a hummingbird. The Aztecs dedicated one of the buildings in their ceremonial center at Tenochtitlan (the forerunner of Mexico City) to the “cut-off hummingbird’s head”. They also believed that the souls of warriors who died in battle, and whose daily task was to transport the sun from the underworld to its mid-day zenith, turned into hummingbirds as they handed over the sun to the Cihuatateo, the souls of women who died in childbirth.
West of the Aztec empire, the Tarascans named their capital city, “Tzintzuntzan”, place of the hummingbird, an onomatopoeic rendering of the sound of their call. More macabre was the belief held by some pre-Columbians that wearing amulets of stuffed or dried hummingbirds would somehow enhance the wearer’s sexual prowess.