From Opus

Aechmophorus occidentalis

Photo by mrcolin2ur
Photo taken: San elijio. USA

[edit] Identification

A large and slender, long-necked North American grebe .

[edit] Adult Breeding

• Blackish-brown above
• Mottled flanks and white below
  • Looks black and white from a distance
• Hindneck and crown blackish-brown
• Dark of crown reaches below eye level
• Red iris
• Bill dark with yellow-green sides
• Yellowish-grey legs

[edit] Adult Non-breeding and Juvenile

Similar but duller and with less clear-cut contrast between dark and light plumage.

[edit] Similar Species

Only likely to be confused with the closely related Clark's Grebe

Extent of black on face and bill colour are the best features distinguishing this species from Clark's Grebe.

[edit] Flight

Upperwing shows bold white bar but less extensive than that of Clark's.

[edit] Distribution

Central Alberta to southern Manitoba and in the northern and western USA from Minnesota and South Dakota westwards and south to California and west Mexico. Only recently separated from Clark's Grebe (A. clarkii) and the exact ranges of the two forms have yet to be elucidated. Resident in south-west of range but elsewhere a migrant. Wintering range extends from the southern coast of British Columbia south to west Mexico, in New Mexico and west Texas and on the Gulf Coast of Texas and Louisiana.

Legend • A. o. occidentalis; year-round • A. o. occidentalis; breeding • A. o. occidentalis; migrating • A. o. occidentalis; wintering • A. o. ephemeralis; year-round Maps/Texts consulted1,2,3,4

[edit] Vagrancy

Vagrants recorded in the Aleutians and on the Atlantic coast of the USA.

[edit] Taxonomy

[edit] Subspecies⁵

• A. o. occidentalis - W North America (se Alaska to n Mexico and Baja Calif.)
• A. o. ephemeralis - Western Mexico; not always recognized

None usually recognised although Mexican birds are sometimes separated as ephemeralis.

[edit] Habitat

Breeds colonially on large freshwater lakes, winters on large inland waters and sheltered sea coasts.

[edit] Behaviour

[edit] Breeding

Begins mid-May in south of range to early June in north. Breeds in large colonies, nest is a heap of vegetation anchored to emergent plants or on the bottom in shallower water.
Eggs: 3-4, whitish with green or buff tinge initially, soon becoming stained (59 x 38mm). Incubated by both sexes for 23 days. Young tended by both sexes and leave nest on hatching.

[edit] Diet

Fish and aquatic invertebrates.

[edit] Voice

Loud and harsh two-note kreek-kreek

[edit] References

1. Sibley, David A. 2000. The Sibley Guide to Birds. New York: Alfred A. Knopf. ISBN 9780679451228
2. Storer, R. W. and G. L. Nuechterlein. 1992. Western Grebe (Aechmophorus occidentalis). The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/026a.
3. Brinkley, Edward S. 2007. Field Guide to Birds of North America. New York: Sterling Publishing Co., Inc. ISBN 9781402738746
4. Howell, Steve N.G. and Sophie Webb. 1995. A Guide to the Birds of Mexico and Northern Central America. New York: Oxford University Press. ISBN 9780198540120
5. Clements James F. 2007. The Clements Checklist of Birds of the World. 6th ed., with updates to October 2008. Ithaca: Cornell University Press. ISBN 9780801445019

[edit] External Links