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Contopus sordiduluswestern wood pewee(Also: western wood-pewee)

By Lynn Gasparella

Geographic Range

Contopus sordidulus are found in western North America, starting in east central Alaska, to northwestern Minnesota, all the way south into southern Baja. In the fall they leave the northern area and head towards the south. During the winter, they can be found migrating even further south to Panama. (DeGraaf and Rappole, 1995; Eastman, 1997)

Habitat

In the summer, C. sordidulus are found in evergreen forests, woodlands, coniferous forests, and also open and closed canopy forests. In the winter they can also be found in agricultural fields, meadows, grasslands, and thickets. In general, western wood-pewees prefer dry environments. (DeGraaf and Rappole, 1995; Shuford, 1993; Small, 1994)

Western wood-pewees are seen close to land but are usually found in tall treetops. They build nests at the end of tree branches. The limbs can either be dead or alive, the birds have no known preference. Usually the branches are at least 5-12 meters above the ground. The nests are weaved out of fiber, grasses, lichens, spider webs, and shredded bark and are shaped like shallow cups. The blending of the color and the shape to the tree allows them to go practically unnoticed resembling stubs on the branches. (DeGraaf and Rappole, 1995; Shuford, 1993; Small, 1994)

  • Aquatic Biomes
  • rivers and streams

Physical Description

Tail: 7-7.62 cm

Western wood-pewees have angular heads with moderate crests. Their flanks and sides are dark brown with blurry streaks that go toward the lower sides. Their tertials are distinctly fringed and are more obvious than their wing bars. Western wood-pewees' tails are short relative to their body proportions. They have long upper tail coverts which reach the midway point of the primary extensions, which are known to be long. Their bills are mostly dark, the lower mandibles are about 50% darker than the unpper mandibles. Their breasts have an olive look. Also, the throats have a whitish color which continues on their bellies and under their tails. (Phillips, et al., 1964; USGS, 2003)

There are differences between the adult and the juvenile plumage. The adult has more of a grayish throat whereas the juvenile has a dull color. Also the wing bars are not as vibrant on juveniles as they are on adult C. sordidulus. (Sibley, 2000)

  • Sexual Dimorphism
  • sexes alike
  • Average mass
    13 g
    0.46 oz
  • Range length
    133.35 to 165.1 mm
    5.25 to 6.50 in
  • Range wingspan
    82.55 to 88.9 mm
    3.25 to 3.50 in

Reproduction

Mating begins in early May but the prime time is around June. The male sings to defend a nesting territory and also uses the songs to attract a mate. The male then takes over a woodland territory that is about 2-6 acres. They are seasonally monogamous. (Harrison, 1978; Eastman, 1997)

The female usually lays 2-4 eggs. When the young are born, the incubation time lasts for about 12 days. By the 7th day, the young have developed all their feathers. The fledging process lasts about 14-18 days and then they leave the nest within the 3 days of fledging. (Harrison, 1978)

  • Breeding interval
    Western wood pewee birds breed once a year
  • Breeding season
    Breeding occurs May to mid July.
  • Range eggs per season
    2 to 4
  • Range fledging age
    14 to 18 days

The young are tended by both parents, but the female is usually at the nest the most during the first 4 days. The young are fed insects. (Eastman, 1997)

  • Parental Investment
  • altricial
  • pre-weaning/fledging
    • provisioning
    • protecting
      • male
      • female

Lifespan/Longevity

Although information on the exact life expectancy of C. sordidulus is unavailable, eastern wood-pewees, which are very similar to western wood-pewee groups, have a life expectancy of about 7 years.

Behavior

Contopus sordidulus appear calm. They perch on the branches for a long amount of time, usually to watch for prey. They fly occasionaly to catch insects that are in the air. (Eastman, 1997)

Home Range

Home range information could not be found for this species.

Communication and Perception

Contopus sordidulus are very hard to differentiate from other birds in their family, such as eastern wood-pewees. But the one thing that does stand out is their communication calls. Eastern wood-pewees have a nasal whistle that sounds like "DREE-yurr" or "breerrr". It sounds very rough. Western wood-pewees sound a bit different, like a plain, sneezy, "brrrt". During breeding a sound is sent out as "tswee-tee-teet". (National Geographic, 1999; Sibley, 2000)

Food Habits

The majority of the time, C. sordidulus feed on insects such as flies, wasps, bees, ants, beetles, moths, and butterflies. On other occasions they eat dragonflies, termites, and spiders. All the insects are caught in the air. Contopus sordidulus hunt from the perch and capture prey by twisting very quickly in the air. Immediately after catching a prey item, they return to the perch. (Coves, 1890; Shuford, 1993)

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods

Predation

Blue jays are nest predators on this species. They will feed on the young in the nest. Hawks are also predators of C. sordidulus. The nest is made up of colors that will allow it to look like a stump on the tree. Camouflage is their way of avoiding predation. (Eastman, 1997)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Contopus sordidulus provide food for blue jays as well as other predators. Western wood-pewees also prey on various insects and spiders. (Coves, 1890; Eastman, 1997; Shuford, 1993)

Economic Importance for Humans: Positive

Songbirds such as western wood-pewees, are important to birdwatchers. In addition, as generalist insectivores, they may affect pest populations.

  • Positive Impacts
  • ecotourism
  • controls pest population

Economic Importance for Humans: Negative

Western wood-pewees have no known negative affects on humans.

Conservation Status

Contopus sordidulus are abundant, but according to the Breeding Bird Survey, there is an increase in Washington but a decrease in British Colombia and Oregon. The decrease could be due to the loss of habitat on breeding grounds and winter grounds. ("Seattle Audubon Society", 2002; "Western Wood Pewee", 1999; DeGraaf and Rappole, 1995)

Other Comments

If people disturb the birds then there is a possibility that the mother will leave her nest. This is usually caused by an overabundance of human activity surrounding them. The mothers would not only leave the nest, but her young as well. (Eastman, 1997)

Contributors

Matthew Wund (editor), University of Michigan-Ann Arbor.

Lynn Gasparella (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, 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

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

arboreal

Referring to an animal that lives in trees; tree-climbing.

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.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

diurnal
  1. active during the day, 2. lasting for one day.
ecotourism

humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.

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.

insectivore

An animal that eats mainly insects or spiders.

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).

migratory

makes seasonal movements between breeding and wintering grounds

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

oviparous

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

riparian

Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

seasonal breeding

breeding is confined to a particular season

sexual

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

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

visual

uses sight to communicate

References

2002. "Seattle Audubon Society" (On-line ). Western wood-pewee. Accessed 04/09/03 at http://www.birdweb.org/birdweb/species.asp?id=282.

Darryl Wheye. 1999. "Western Wood Pewee" (On-line). Accessed April 09, 2003 at http://www.stanfordalumni.org/birdsite/.

Coves, E. 1890. Key to North American Birds. Boston: Estes and Lauriat.

DeGraaf, R., J. Rappole. 1995. Neotropical Migratory Birds Natural History, Distribution, and Population Change. New York: Comstock Publishing Associates.

Eastman, J. 1997. Birds of Forest, Yard, & Thicket. Pennsylvania: Stackpole Books.

Harrison, C. 1978. A Field Guide to the Nests, Eggs, and Nestlings of North American Birds. Glasgow, United Kingdom: William Collins Sons & Co Ltd.

National Geographic, 1999. Field Guide to the Birds of North America. Washington DC: National Geographic.

Phillips, A., J. Marshall, G. Monson. 1964. The Birds of Arizona. Arizona: University of Arizona Press.

Price, J., S. Droege, A. Price. 1995. The Summer Atlas of American Birds. California: Harcourt Brace & Company.

Shuford, D. 1993. The Marin County Breeding Bird Atlas. California: Bushtit Books.

Sibley, D. 2000. The North American Bird Guide. United Kingdom: Pica Press.

Small, A. 1994. California Birds Their Status and Distribution. California: IBIS Publishing Company.

USGS, 2003. "Western wood-pewee Contopus sordidulus Identification Tips" (On-line ). Accessed 03/19/03 at http://www.mbr-pwrc.usgs.gov/id/framlst/account/h4620id.html.

USGS, 2003. "Western wood-pewee Contopus sordidulus Life History Groupings" (On-line ). Accessed 03/19/03 at http://www.mbr-pwrc.usgs.gov/id/framlst/button/lh4620.html.

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