The ruby-throated hummingbird (Archilochus colubris) is the only known species of hummingbird to breed or even regularly reside in eastern North America. The breeding range of ruby-throated hummingbirds is the largest of all the species of hummingbirds in North America.

Fast Facts: Ruby-Throated Hummingbird Scientific Name: Archilochus colubris

Archilochus colubris Common Name: Ruby-throated hummingbird

Ruby-throated hummingbird Basic Animal Group: Bird

Bird Size: 2.8–3.5 inches in length

2.8–3.5 inches in length Weight: 0.1–0.2 ounces

0.1–0.2 ounces Lifespan: 5.3 years

5.3 years Diet: Omnivore

Omnivore Habitat: Summers in eastern North America; winters in Central America

Summers in eastern North America; winters in Central America Population: Estimated 7 million

Estimated 7 million Conservation Status: Least Concern

Description

Male and female ruby-throated hummingbirds differ in their appearance in several ways. Males are more vibrantly colored than females. Males have metallic emerald-green plumage on their back and metallic red feathers on their throat (this patch of feathers is referred to as a "gorget"). Females are duller in color, with less vibrant green feathers on their back and no red gorget, their throat and belly plumage is a dull grey or white. Young ruby-throated hummingbirds of both sexes resemble the plumage of adult females.

Like all hummingbirds, ruby-throated hummingbirds have small feet that are not well suited to perching or hopping from branch to branch. For this reason, ruby-throated hummingbirds use flight as their primary means of locomotion. They are superb aerialists and are capable of hovering with wingbeat frequencies of up to 53 beats per second. They can fly in a straight line, up, down, backward, or hover in place.

The flight feathers of ruby-throated hummingbirds include 10 full-length primary feathers, six secondary feathers, and 10 rectrices (the largest feathers used for flight). Ruby-throated hummingbirds are tiny birds, they weigh between about 0.1 and 0.2 ounces and measure between 2.8 to 3.5 inches in length. Their wingspan is about 3.1 to 4.3 inches wide.

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Habitat and Range

This hummer breeds in the summertime, throughout the eastern United States and Canada. In the autumn, the birds migrate to their wintering grounds in Central America from northern Panama to southern Mexico, although some winter in parts of South Florida, the Carolinas, and along the Gulf Coast of Louisiana. They prefer habitats which have lots of flowers, such as fields, parks, backyards, and open clearings in forests. Migration round-trips can be as long as 1,000 miles.

Migration patterns of ruby-throated hummingbirds vary: Some migrate between their breeding and wintering grounds by flying across the Gulf of Mexico while others follow the Mexican gulf coastline. Males start their migration before females and juveniles (males and females) follow on after the females. They migrate south between August and November, and north again between March and May.

Diet and Behavior

Ruby-throated hummingbirds feed primarily on nectar and small insects. They occasionally supplement their diet with tree sap if nectar is not readily available. When gathering nectar, ruby-throated hummingbirds prefer to feed on red or orange flowers such as red buckeye, trumpet creeper, and red morning glory. They often feed while hovering at the flower but also land to drink nectar from a conveniently located perch.

Scientists have long been fascinated by the hummingbird's hovering flight. Unlike larger birds, they can perform sustained hovering as well as regular cruise flight and maneuvering. Like insects, they use a leading edge vortex over their wing surfaces to gain lift in the flight, but unlike insects, they can invert their wings at the wrist joint (insects do that with a pulse of muscles).

Reproduction and Offspring

During the June–July breeding season, ruby-throated hummingbirds are highly territorial, behavior which is reduced during other times of the year. The size of the territories that males establish during the breeding season varies based on the availability of food. Males and females do not form a pair bond and remain together only during courtship and mating.

Female ruby-throated hummers lay up to three broods a year, in groups of one–three eggs, most typically two, which hatch after 10–14 days. The mother continues to feed the chicks for another four to seven days, and the chicks fledge and leave the nest 18–22 days after hatching. Hummingbirds become sexually mature the next season about one year of age.

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Threats

There are an estimated 7 million ruby-throated hummingbirds in the world, and they are classified as Least Concern by the International Union for Conservation of Nature (IUCN), and the ECOS Environmental Conservation Online System does not list them as endangered at all. However, continuing climate change affecting their migration patterns and those of related species may have impacts that are as yet unclear.

Northern migration dates of ruby-throated hummingbirds have already been measurably impacted by global climate change, with warmer winter and spring temperatures correlating with earlier arrivals, especially at lower latitudes (below 41 degrees north, or generally south of Pennsylvania). In a 10-year study (2001–2010), the differences ranged from 11.4 to 18.2 days earlier in warmer years, leading to concerns about competition for food resources going forward.