Selasphorus sasinAllen's hummingbird

Geographic Range

Allen's Hummingbird, Selasphorus sasin, is a migratory bird which summers along the pacific coast of the United States from Oregon to southern California. During the winter it migrates to northwestern Mexico.

(Peterson 1990, Terres 1980)


The Allen's Hummingbirds can be found in bushy woods, gardens, flower filled mountain meadows, and parks.

(Cassidy 1990, Stokes 1996)

Physical Description

Allen's Hummingbirds are among the smallest birds, they are only 7.5 to 9 cm (3-3.5 in.) long and typically weigh a little over 3 grams (0.1 oz.). In appearance they resemble their closest relative, the Rufous Hummingbird. A male Allen's hummingbird has a fiery red-orange throat, white collar, and metallic green on its back and cap. The female's upper body is green. The tail and sides are orange-brown and the throat and central belly is white with iridescent dots on its throat.

(Stokes 1996, Farrand 1988, Terres 1980)

  • Average mass
    3 g
    0.11 oz
  • Average mass
    3 g
    0.11 oz
  • Average basal metabolic rate
    0.06853 W


Female Allen's hummingbirds usually start building their nest before they mate. After mating the female alone has to finish the half built nest. She uses moss, bits of vegetation, spider webs, bark flakes, and pine needles to finish the cup-shaped nest. This nest is only about 4 cm (1.5 in.) from top to bottom and 4-5 cm (1.5-2 in.) in diameter. She lays only two eggs, which are about 1 cm (1/2 in.).

The female alone incubates the eggs for about 16 to 22 days. Once the baby hummingbirds are hatched, the mother fearlessly protects her young. She alone has the duty to feed them until they are ready to leave the nest. She feeds them by inserting her bill into the baby's mouth and regurgitating food from her crop. Chicks usually fledge (leave the nest) in about 22 days and are immediately independant of their mother.

(Baicich 1997, Ehrlich 1988, Terres 1980, Stokes 1989)

  • Average eggs per season
  • Average time to hatching
    16 days



Individual male and female Allen's Hummingbirds defend separate feeding territories. During the breeding season, which typically begins in February the Female hummingbirds begin to visit male territories. At first a male might be aggressive towards her, but then he will do aerial displays. The male uses a J-shaped flight as a signal. He will fly up about 23 m (75 ft.) and come down and up about 7 m (25 ft.) He will then fly in a back-and-forth flight that resembles a giant pendulum. At the peak of the arc he will make a prolonged buzz. The female hummingbird then leads him closer to her feeding territory to begin copulation, mating lasts about 3-5 seconds, and then the male returns to his territory.

When the Allen's Hummingbird is not feeding during the night its body goes into a state of torpor. It lets body heat escape and its heart rate drops dramatically. It clings to a branch and sits almost life-less to conserve energy. At sunrise its body temperature starts going up again and it is ready to start feeding.

Most hummingbirds including the Allen's Hummingbird are not social animals. Since they spend most of their time feeding on nectar, they are better off feeding alone. Each bird claims its territory in which to feed and they become very aggressive birds if there are any trespassers. The male hummingbird will use its aerial flights and intimidation displays to chase away predators and trespassers.

(Cassidy 1990, Stokes 1989, Arizona-Sonora Desert Museum 1998)

Communication and Perception

Food Habits

Allen's Hummingbird has a long narrow bill and long tongue. This feature allows it to obtain nectar from flowers. They feed every ten to fifteen minutes and visit approximately 1,000 flowers a day. Nectar is their main source of energy, but they also obtain protein from small insects like flies, ants, small beetles, tiny wasps, and other small insects. Because the hovering flight used by these birds to gather nectar requires phenomenal amounts of energy, the Allen's hummingbird has to consume over twice its weight of nectar each day.

(Cassidy 1990, Arizona-Sonora Desert Museum 1998, Stokes 1989)

Economic Importance for Humans: Positive

There is neither positive nor negative economic importance for the Allen's Hummingbird, but they do help in the pollination of flowers.

Conservation Status

Other Comments

Prolonged hovering and flying backwards are unique to hummingbirds. This amazing flight ability requires huge amount of food (caloric input) in order to sustain the flights. This is why hummingbirds have to constantly be feeding during the day and go torpid at night. If a human used energy at the rate that a hummingbird does, he/she would have to consume about four hundred pounds of potatoes and a thousand quarter-pound hamburgers every day.

(Arizona-Sonora Desert Museum 1998)


Noemi Pineda (author), Fresno City College, Carl Johansson (editor), Fresno City College.



living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map


uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


uses smells or other chemicals to communicate


animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.


forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.


offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).


having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.


reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.


reproduction that includes combining the genetic contribution of two individuals, a male and a female


uses touch to communicate

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.


A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.


uses sight to communicate


Arizona-Sonora Desert Museum, 1998. "The Secret Lives of Hummingbirds" (On-line). Accessed February 13, 2001 at

Baicich, P., C. Harrison. 1997. A Guide To The Nests, Eggs, and Nestlings of North American Birds 2nd. Ed.. San Diego, California: Academic Press.

Cassidy, J. 1990. Book of North American Birds. New York: The Reader's Digest Association, Inc..

Ehrlich, P. 1988. The Birder's Handbook A Field Guide To The Natural History of North American Birds. New York: Simon & Schuster Inc..

Farrand, J. 1988. An Audubon Handbook Western Birds. New York: McGraw-Hill Book Company.

Peterson, R. 1990. Peterson Field Guides Western Birds 3rd Ed.. Massachusetts: Houghton Mifflin Company..

Stokes, D., L. Stokes. 1996. Stokes Field Guide To Birds. New York: Little, Brown & Company.

Stokes, D., L. Stokes. 1989. The Complete Guide To Attracting Identifying & Enjoying Hummingbirds. New York: Little, Brown & Company.

Terres, J. 1980. The Audubon Society Encyclopedia of North American Birds. New York: Alfred A. Knopf.