Animalia Life

Aechmophorus occidentalis
TAXONOMY
Podiceps occidentalis, Lawrence, 1858, Fort Steilacoom, Washington. Two subspecies.
OTHER COMMON NAMES
French: Grиbe йlйgant; German: Renntaucher; Spanish: Achichilique Comъn.
PHYSICAL CHARACTERISTICS
21.6–29.5 in (55–75 cm); 1.8–4.0 lb (823–1826 g), A. o. ephemeralis smallest, females decidedly smaller than males. Body narrow, neck very long, bill long and sharply pointed. Head with slight crest. Adult breeding: cap to below eye black, rest of upperparts blackish with faint gray scales on back; underparts white, sides spotted gray. Wings with variably sized white bar across remiges. Eyes red, bill buffy green with black ridge. Nonbreeding: similar, but crown duller, less crested and less clearly demarcated from white. Immature: like non-breeding, but crest even shorter, back without scales, and facial pattern more diffuse, sometimes with white on lores.
DISTRIBUTION
A. o. occidentalis: west to North America, in winter on coast of Texas and Pacific coast south to Baja California; A. o. ephemeralis: resident in central Mexico.
HABITAT
Breeds on large lakes and marshes with large expanses of open fresh or brackish water and with reedy shores. In winter mostly on salt lakes or in deep offshore waters on coast.
BEHAVIOR
Colonial, sometimes several thousand together.
FEEDING ECOLOGY AND DIET
Feeds almost entirely on large variety of fish, often spiking them, usually in fairly deep water, but on average closer to shore than Clark’s grebe.
REPRODUCTIVE BIOLOGY
Courtship display well developed. Nests 3–12 ft (2–4 m) apart in colonies. Eggs 3–4, incubation period 22–24 days. Young independent at 8 weeks.
CONSERVATION STATUS
Not threatened. Population estimated at 70,000–100,000 birds, only few in Mexico.
SIGNIFICANCE TO HUMANS
None known.

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