Female Ruby-throated hummingbird approaching jewelweed. Photo courtesy of Rick Remington

A route of evanescence

With a revolving wheel;

A resonance of emerald,

A rush of cochineal;

And every blossom on the bush

Adjusts its tumbled head, —

The mail from Tunis, probably,

An easy morning’s ride.

In 1880, after 20 years of trying, Emily Dickinson was finally satisfied that her deceptively simple, elegant poem captured the essence of the Ruby-throated hummingbird. Much ado has been made over the meaning of the final two lines, because hummingbirds live only in the western hemisphere.

About 340 species of hummingbirds live in our hemisphere, but only the Ruby-throat nests in our vicinity. People glimpse this exquisite blur of a bird at feeders or in gardens, and occasionally perched on its short, weak legs. It never walks or hops but it sometimes shuffles to the side on a branch. Its order name, Apodiformes, means “without feet,” indicating that early taxonomists were misinformed.

The Ruby-throat’s breeding range includes west-central Canada and, in the United States, the entire area running almost straight south of the 100th meridian and east over to the coast, in mixed and deciduous forests. These tiny birds are three-and-a-half inches long and weigh in at about one-tenth of an ounce, a little less for males. They winter primarily in Mexico and Central America. It was long thought that their route included a remarkable non-stop journey over the Gulf of Mexico. Some reports, however, suggest that many follow a coastal route, and more study is needed.

Males are the first to migrate to their winter and summer territories, then come females and finally juveniles. They fly individually during daylight. In spring, there is no evidence that their arrival coincides with the flowering of any particular plant, although the flowering of wild columbine has been suggested as synchronous with breeding. In the absence of flowers or insects, Ruby-throats depend upon Yellow-bellied sapsuckers, Sphyrapicus varius, woodpeckers that arrive earlier and drill holes in trees. Insects are trapped in the oozing sap, and both the sap and insects attract hummingbirds. Some researchers suggest that Ruby-throats time their spring migration with the arrival of sapsuckers. Migration to wintering grounds may be associated with the peak flowering of jewelweed, which is orange.

Floral nectar has a low sugar concentration. Flowers known to attract hummingbirds are usually tubular: buckeye, columbine, red morning-glory, wild bergamot or beebalm, honeysuckle, cardinal flower, catchfly and even lilacs. A study of the orange turk’s-cap lily showed that hummingbirds preferred first-day flowers, which contain more nectar. Red flowers, according to Cornell Birds of America Online,”are thought to have co-evolved with hummingbirds.” The same source suggests, however, that hummingbirds are attracted to feeder locations according to the amount of energy they provide rather than to any particular color.

Hummingbirds are important pollinators and may carry away 10 times more pollen on their bills and crowns per floral visit than do bees in their pollen sacs. Trumpet creeper may be primarily adapted to the Ruby-throat for pollination.

Insects make up as much as half of the hummingbird’s diet, caught in mid-air by “hawking.” Ruby-throats hover while gleaning spiders, aphids and insect eggs from leaves and bark. Hummers eat about one-and-a-half times their body weight in nectar daily, in addition to insects. Before migration, Ruby-throats are gluttons, doubling their body weight in just 7-10 days

When a male hummingbird arrives in spring, he selects a territory of about a quarter acre with plenty of cover, good perches and a good food source. He protects it fiercely. If he finds better grounds, he will move. Males display when females enter their territories. They perform U-shaped dives and sideways arcs above the female. These displays, however, could be aggressive rather than for courting. After mating, males and females go their separate ways and are almost certainly polygamous.

The female selects a nest site and begins building before mating. She incubates the eggs, feeds the young and protects the nest. Using bud scales from winter trees as the foundation, she adds spider silk, lichen and plant down. Two eggs resembling tic-tacs are incubated for 14-17 days. The nestling period varies widely, averaging 18-20 days. The female continues caring for her young for about a week after they fledge.

Male and female Ruby-throats are emerald green on their backs and buff-colored on their bellies. They have long, slender bills. Their tongues, which are forked and have brushy ends, collect sap and nectar by capillary action, not by sipping as if through a straw. Males have notched tails; female tails are rounded with spots on the outer edges.

It is the iridescent scarlet (cochineal) on the male’s throat, the gorget, that captivates spectators. The color of these throat feathers is the result of complex feather structure, not pigment. As explained by Avian Video Center’s Tom Kaminski, creator of the video Hooked on Hummingbirds, “the variations in color are the result of light striking the feathers at different angles as the bird, sun and viewer move relative to one another. Colors appear at their most vibrant with the sun behind the viewer and the bird in front.”

The Ruby-throat dazzles not only because of color but because of its flight. It darts forward and backward, even upside down, or hovers, with a wingbeat averaging 53 beats per second. When chasing, it may sound like a dive-bomber. The sexes sound different; the female, with her longer, wider primary wings, produces a lower-pitched and softer hum than the male.

Although they are vertebrates, hummingbirds fly more like insects. Apparently, it’s all in the twist. The hummingbird’s arm parts are fused, and its wrist is close to its shoulder. It is the hummingbird’s hand that one sees as its wing. Recently, Tyson Hedrick, a biologist at the University of North Carolina in Chapel Hill, led a study that filmed hummingbirds flapping “their wings by twisting the humerus (upper arm bone), rather than flapping it up and down from the shoulder like other birds.”

Attracting hummingbirds is a delight and a big responsibility if using a feeder. Feeders must be cleaned regularly and the contents, one part sugar to four parts water, must be changed every other day to avoid fermentation. Alternatives preferred by this writer are to hang flower baskets or to create a garden of native tubular flowers blooming in a colorful succession from spring through late summer.

Libby Hill

Libby Hill is the author of "The Chicago River: a Natural and Unnatural History. She has been writing about birds and trees and Evanston's natural history for the Roundtable since 2004.