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Aechmophorus occidentaliswestern grebe

By Megan Pease

Geographic Range

Aechmophorus occidentalis is commonly found from Canada through California, and sometimes in Mexico. It usually occurs in the great plains and western states, but occasionally can be found in the eastern half of the United States.

Habitat

Aechmophorus occidentalis is a migratory bird. It lives on freshwater lakes that have rushes and tules during the breeding season. It usualy stays on prairie lakes in British Columbia and California, and sometimes as far down as Mexico. In the winter A. occidentalis lives on the Pacific coast.

  • Aquatic Biomes
  • lakes and ponds
  • coastal

Physical Description

Aechmophorus occidentalis is the largest of the North American grebes, it ranges from 56-74 cm in length. It has a long neck and bill. The feet are at the far back of the body and the tail is reduced. The ankle and toe joints are very flexible to aid in manueverability in the water. The head, neck, and body are a blackish brown color from above, and white from below. The Western Grebe has a dull yellow or olive-colored bill and red eyes surrounded by dark coloration. In flight a white wing stripe is exposed. The sexes are monomorphic year round.

Aechmophorus clarkii, Clark's grebe, was only recently recognized as a separate species. Clark's grebes have white surrounding the eye and a bill that is bright yellow to orange-yellow. Their flanks have more white areas and the back is a lighter gray.

  • Average mass
    1400 g
    49.34 oz
  • Average mass
    1475.5 g
    52.00 oz
    AnAge

Reproduction

Aechmophorus occidentalis breeds in the spring. It has a very elaborate courtship behavior. The couple will dance, posture, and run across the water. Many grebes ussually mate at the same time. The female lays three to five bluish white colored eggs. The nest floats on the water in the reeds. Both sexes take care of the young. They become very territorial during nesting. To avoid other nesting pairs the parents dive from the nest and swim underwater to go to feeding grounds.

  • Average eggs per season
    3
    AnAge
  • Average time to hatching
    23 days
    AnAge

Lifespan/Longevity

Behavior

Aechemophorus occidentalis is a solitary bird except when it migrates. It migrates in a loosely formed flock, and then spreads out to feed when it lands. During breeding season the pair nests near other birds on the lake, but becomes very territorial and aggressive towards other nesting pairs. The courtship behavior of A. occidentalis is very complex. They go through a series of special displays, postures, and calls to attract a mate. There is no special hierarchy that determines who gets to mate. It relies on who can attract the female.

Communication and Perception

Food Habits

Aechmophorus occidentalis is a carnivore. It mostly eats fish, but also eats insects, mollusks, and crustaceans. The Western grebe is an aggressive hunter. It dives under the water and spears fish with its long bill.

Economic Importance for Humans: Positive

Aechmophorus occidentalis is of economic interest to tourists, scientists, and developers. Tourists regularly go to wildlife refuges and preserves to go birdwatching. This brings entrance fees to the wildlife parks and refuges. Scientists are interested in A. occidentalis because its habitat (the wetlands) is being taken over by development. The fact that they are still thriving shows the condition of the environment.

Economic Importance for Humans: Negative

There were no negative influences found.

Conservation Status

Aechemophorus occidentalis is not endangered or threatened. They are however are affected by oil spills and insecticides found in their food. The insecticides affect their breeding. Another danger to this bird is the reduction in habitat. Lakes and marshes that A. occidentalis occupies are being taken over by human development. At this time A. occidentalis hasn't been affected very much by these threats.

Contributors

Megan Pease (author), Fresno City College, Jerry Kirkhart (editor), Fresno City College.

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

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.

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

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.

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

visual

uses sight to communicate

References

Perrins, C., A. Middleton. 1993. The Encyclopedia of Birds. New York: Facts on File, Inc..

Robbins, C., B. Bruun, H. Zim. 1996. "Western grebe Aechmophorus occidentalis" (On-line). Accessed October 23, 2000 at http://www.mbr-pwrc.usgs.gov//id/framlst/Idtips/h0010id.html.

Sibley, D. 2000. National Audubon Society The Sibley Guide to Birds. New York: Alfred A. Knopf.

Udvardy, M. 1977. The Audubon Society Field Guide to North American Birds. New York: Alfred A. Knopf, Inc..

Walters, M. 1994. Birds' Eggs. New York: Dorling Kindersley.

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