Cyanocitta stelleriSteller's jay

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Geographic Range

Starting from the southern coast of Alaska, the range extends continuously southward through the Rocky Mountain region of the western United States into Mexico, and scatters through Central America, terminating in north-central Nicaragua. The western edge of distribution lies along the Pacific coast, and reaches eastward as far as eastern Colorado (Greene et al. 1998; National Geographic Society 1987).

Habitat

Cyanocitta stelleri primarily reside within coniferous forests, though deciduous forests are also chosen. The altitude of habitat location ranges between 1000-3500 meters. Although C. stelleri are non-migratory birds, migration from high to lower elevation is known to take place during the winter season (Greene et al 1998; Kaufman 1996; National Geographic Society 1987; Terres 1980).

Physical Description

Adult C. stelleri average in length ranging from 30 to 34 cm., with a mass of 100-140 g. The wingspan varies from approximately 45 to 48 cm. Distinguishing characteristics include a black, thick, pointed bill typical of corvids. Coloration consists of dark blue/cobalt plumage throughout most of the body, including the wings, coverts and rectrices. The wings and rectrices also possess a pattern of black barring, perpendicular to the rachis of the feathers. The entire head is usually black, although certain subspecies such as C. stelleri macrolopha may have white streaks along the forehead and supercilium. Other races have even further deviations from typical C. stelleri plumage. Perhaps the most conspicuous characteristic of C. stelleri is the presence of a tall, black crest. Juveniles are distinguished by a sooty gray coloring on the head and body, as well as a shorter crest. The sexes are nearly monomorphic, with the exception of fainter and narrower bars in the barring pattern of females (Green et al. 1998; National Geographic Society 1987; Rue III 1970; Terres 1980).

  • Range mass
    100 to 140 g
    3.52 to 4.93 oz

Reproduction

Steller's Jays are monogamous. They perform a display upon initial encounters called Sexual Sidling. After a mate has been selected, both individuals participate in selecting a site and building the nest. The nest is a cup structure, typically made up of mud and durable material such as thick plant fibers, twigs and rootlets. The location of the nest is above the ground within trees. The height usually ranges between 3-12 m., though lower nests have been found. Females have the ability to lay one egg per day, with the clutch ranging between 2-6 eggs. The incubation time is approximately 16 days. The female may do all the incubation, although it has been claimed that males may also incubate. The rate of development of the young after hatching is not completely known, though the first molt probably takes place after 2 weeks, while flight is thought to first take place after 3 weeks (Greene et al 1998; Kaufman 1996; Terres 1980).

  • Average eggs per season
    4
    AnAge

Lifespan/Longevity

Behavior

The Steller's Jay is a highly social species. Flocks of various sizes form often, with mates rarely parting. As a consequence of frequent flock formation, C. stelleri have several forms of agonistic behavior. One form involves aggressive fighting while flying in the air. The two birds involved will fly upward, and attempt to grasp each other with the feet while pecking each other with their bill. Crest displays and an act called Aggressive Sidling are also used for establishing social status. Steller's Jays use wing spreading to express submission. Steller's Jays also use antipredator displays, with mobbing (gathering in large numbers to vocally harass and fly at predators)the primary form of defense. Typical predators include accipiter hawks such as Cooper's Hawks. Vocal communication is fairly complex, with calls including a harsh "shack, shooka" sound, and mimicry of a red-tailed hawk. The song consists of a moderate to soft warble (Greene et al 1998; National Geographic Society 1987).

Communication and Perception

Food Habits

Cyanocitta stelleri are omnivorous, with a diet consisting primarily of nuts, pine seeds and acorns. Like other corvids, Steller's Jays eat the eggs of other birds. Foraging takes place on the ground and within the trees. Scavenging is also known to take place, most of which occurs within developed areas and campgrounds. During winter, C. stelleri depend upon seeds and nuts, though they may also scavenge and even prey upon small invertebrates that happen to be active within the habitat at the time (Greene et al 1998; Kaufman 1996; Sieving et al 1999).

Economic Importance for Humans: Positive

Cyanocitta stelleri do not have any strong economic/agricultural contributions, though their consumption of insects may have an impact on pest control.

Economic Importance for Humans: Negative

Since Cyanocitta stelleri are often observed scavenging at picnic and campsites within their habitats, there exists the possibility of being considered as a nuisance (Greene et al 1998; National Geographic Society 1987).

Conservation Status

Cyanocitta stelleri is neither endangered nor threatened according to any of the organizations involved with biodiversity and conservation.

Other Comments

Cyanocitta stelleri and the Blue Jay, Cyanocitta cristata, are a classic example of allopatric speciation, with the Rocky Mountain Range being the probable source of divergence. Hybrids have been known to occur along the central United States within the Great Plains region. The zone of hybridization is maintained through a "sink" mechanism known as dynamic equilibrium (Greene et al 1998).

Contributors

Hugh Chung (author), University of Michigan-Ann Arbor, Terry Root (editor), University of Michigan-Ann Arbor.

Glossary

Nearctic

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

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

acoustic

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.

chaparral

Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.

chemical

uses smells or other chemicals to communicate

endothermic

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

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

iteroparous

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).

motile

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.

oviparous

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

sexual

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

tactile

uses touch to communicate

taiga

Coniferous or boreal forest, located in a band across northern North America, Europe, and Asia. This terrestrial biome also occurs at high elevations. Long, cold winters and short, wet summers. Few species of trees are present; these are primarily conifers that grow in dense stands with little undergrowth. Some deciduous trees also may be present.

visual

uses sight to communicate

References

Greene, E., W. Davison, V. Muehter. 1998. Steller's Jay: Cyanocitta stelleri.. The Birds of North America, 343.

Kaufman, K. 1996. Lives of North American Birds. New York: Houghton Mifflin Co..

National Geographic Society, 1987. Field Guide to the Birds of North America. Washington, D.C.: National Geographic Society.

Rue III, L. 1970. Pictorial Guide to the Birds of North America. New York: Thomas Y. Crowell Company.

Sieving, K., M. Wilson. 1999. A Temporal Shift in Steller's Jay Predation on Bird Eggs. Canadian J. of Zoology, 77: 1829-1833.

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