Ruby-throated hummingbirds are tiny. They are 7.5 to 9.0 cm long. Males weigh about 3.4 g. Females weigh about 3.8 g. Males and females have and iridescent green back and head and a white belly. Males have a bright red shiny throat and a forked tail. Females have a dull grayish throat, and a square, white-tipped tail. Young ruby-throated hummingbirds look like adult females. (Robinson, et al., 1996)
Ruby-throated hummingbirds are found in North and Central America. They breed throughout the eastern United States, east of the 100th meridian. They also breed in southern Canada where there is eastern and mixed deciduous forest. The species spends winters in southern Mexico, Central America (as far south as Costa Rica), and in the West Indies. (Robinson, et al., 1996)
During the breeding season, this species lives in deciduous and pine forests. They also nest along forest edges, in orchards, and in gardens. During the winter, ruby-throated hummingbirds live in tropical deciduous forests, citrus groves, forest edges, hedgerows, along rivers and marshes, and in old fields. (Robinson, et al., 1996)
Ruby-throated hummingbirds are probably polygynous (one male mates with many females). However, mating behavior has not been studied very well in this species. It is also possible the each female mates with many males.
Males return to the breeding area in the spring and find a territory before the females arrive. When the females return, males try to attract them by performing courtship displays. When a female enters a male’s territory, the male fluffs out his red-throat feathers and begins harassing the female. He may also perform a “dive display” by diving over and over above the females head. If the female perches, the male starts flying back and forth in front of her very quickly. During this display, the male's wings can beat up to 200 times per second. If the female is receptive to the male, she may give a “mew” call and assume a solicitous posture with her tail feather cocked and her wings drooped. After a male and female copulate, they do not stay together. The male searches for another female to copulate with and the female builds the nest and raises the chicks alone. (Robinson, et al., 1996)
The female chooses a nest site and builds a nest. She builds the nest near the tip of a branch. Females usually chose a spot that is above an open area and shaded by leaves. The nests are made of plant material, spider webs, bud scales and pine resin. The outside of the nest is decorated with lichens.
When the nest is finished, the female lays 2 eggs. She incubates the eggs for 10 to 14 days. The chicks are helpless when they hatch, and must be kept warm by the female. The chicks leave the nest when they are 18 to 22 days old. The female keeps feeding them until they are 22 to 25 days old.
These birds probably breed the next year when they are 1 year old. Ruby-throated hummingbirds can raise up to three broods each year. (Robinson, et al., 1996)
Male ruby-throated hummingbirds do not help to raise their chicks. After the male and female copulate, the female raises the chicks alone. She builds the nest, lays the eggs, incubates them, broods the chicks and feeds them until they are 22 to 25 days old. The male does not provide any parental care. (Robinson, et al., 1996)
The oldest wild ruby-throated hummingbird female lived at least 9 years. The oldest known male lived 5 years. Males often do not live as long as females because they have to spend so much energy defending a territory during the breeding season, and then they have to migrate to their wintering grounds, which also uses a lot of energy. (Robinson, et al., 1996)
Ruby-throated hummingbirds are solitary. Males of this species are territorial, and they defend their territories mostly using calls. If a male hummingbird’s territory is invaded, he will call at the intruder. If the intruder doesn’t leave, the male will chase him away.
Ruby-throated hummingbirds are diurnal. They are active during the day. In very cold weather, ruby-throated hummingbirds save energy by entering torpor. Torpor is similar to hibernation; the hummingbird’s heart and other organs slow down and the body cools down while the hummingbird sleeps. This helps these hummingbirds survive in cold weather.
Ruby-throated hummingbirds migrate in the spring and fall. In the spring, they fly north to their breeding grounds. In the fall, they fly south to Mexico and Central America. Many ruby-throated hummingbirds migrate as far as 800 km each way. They may fly across the Gulf of Mexico without stopping. Before leaving for migration, hummingbirds store energy for the trip in a layer of fat. They may store so much energy that they double their weight before leaving in the spring or fall. Hummingbirds arrive in the spring around the time when their food plants begin flowering. (Robinson, et al., 1996)
There is no information available about the home range of this species at this time. (Robinson, et al., 1996)
Ruby-throated hummingbirds use touch, sight, hearing and perhaps smelling to communicate and to understand their environment. Ruby-throated hummingbirds can see blue-violet light and near UV light. These are types of light that humans and many other animals cannot see. Ruby-throated hummingbirds may use this special vision to help them find food. Ruby-throated hummingbirds may also be able to find food sources using smell.
Ruby-throated hummingbirds have a fast, squeaky call. They use this call most often to threaten each other. For example, if one male invades the territory of another male, the male that owns the territory may warn the other to leave by calling at him. If calling doesn't work, the male may chase the other out of his territory. He may even dive at the new male, and try to strike him with his feet or his bill. (Robinson, et al., 1996)
Ruby-throated hummingbirds eat floral nectar and small insects. When nectar is not available, they also eat tree sap. Ruby-throated hummingbirds eat nectar from many different flowering plants. Some of the plants that hummingbirds take nectar from are red buckeye (Aesculus pavia), jewelweed, columbine (Aquilegia canadensis), trumpet creeper (Campsis radicans), red morning-glory (Ipomea coccinea), trumpet- or coral-honeysuckle (Lonicera sempervirens), fly-honeysuckle (Lonicera canadensis), cardinal flower (Lobelia cardinalis), catchflies (Silene) and fire-pink (Silene virginica). Some of the insects that ruby-throated hummingbirds eat include mosquitoes, spiders, gnats, fruit flies (genus Drosophila) and small bees.
Ruby-throated hummingbirds are attracted plants that produce red flowers. They consume twice their body weight in food each day. While eating, these birds hover above the plant and use their long beaks to suck out the flower's' nectar. Ruby-throated hummingbirds get water from the nectar they drink. They do not need to drink water. (Robinson, et al., 1996)
Adult ruby-throated hummingbirds are killed by raptors, including loggerhead shrikes and sharp-shinned hawks. Blue jays eat nestlings. House cats are probably the most common predator of ruby-throated hummingbirds. (Robinson, et al., 1996)
This species is an important pollinator for many plants. Some species such as trumpet creeper seem to have flowers that are shaped especially to fit the long-skinny bills of ruby-throated hummingbirds.
Ruby-throated hummingbirds eat the same foods as many other hummingbird species. When they live in the same place, ruby-throated hummingbirds have to compete with the other species for food. (Robinson, et al., 1996)
There are no known adverse affects of ruby-throated hummingbirds on humans.
Ruby-throated hummingbirds pollinate many native and cultivated plant species.
Ruby-throated hummingbirds were hunted for collection during the 1800’s because of their small size and bright red feathers. Today, ruby-throated hummingbirds are quite common. There are about 7,300,000 ruby-throated hummingbirds in the world.
Ruby-throated hummingbirds are protected under the Migratory Bird Treaty between the U.S. and Canada. They are also protected by Appendix II of the Convention on International Trade in Endangered Species. (Robinson, et al., 1996)
Hummingbirds can fly backwards and upside down. They can also hover in one place. They are much better at such aerial tricks than most birds. They also have fewer feathers on their body than any other bird species.
Each hummingbird species makes a different humming sound when it flies. The humming sound is made by the wings, and is determined by how quickly the hummingbird beats its wings. Ruby-throats beat their wings extremely fast (53 beats per second).
Ruby-throated hummingbirds use a lot of energy each day in order to fly so quickly and to hover. (Robinson, et al., 1996)
Kari Kirschbaum (author, editor), Animal Diversity Web.
Marie S. Harris (author), University of Michigan-Ann Arbor, Robert Naumann (author), University of Michigan-Ann Arbor.
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Johnsgard, Paul, A. The Hummingbirds of North America. Smithsonian Institution Press, 1983.
Mackenzie, John, P.S. Birds of Eastern North America. McGraw Hill Ryerson Limited, 1976.
Tyrell, Esther, Quesada. Hummingbirds: Their Life and Behavior. Crown Publishers Inc., 1985.
Robinson, T., R. Sargent, M. Sargent. 1996. Ruby-throated hummingbirds (Archilochus colubris). Pp. 1-16 in A Poole, F Gill, eds. The Birds of North America, Vol. 204. Philadelphia, PA: The Academy of Natural Sciences and Washington DC: The American Ornithologists Union.