Aechmophorus
| Aechmophorus Temporal range: Late Pliocene to present |
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|---|---|
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| Clark's grebe | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Podicipediformes |
| Family: | Podicipedidae |
| Genus: |
Aechmophorus Coues, 1862 |
| Species | |
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A. occidentalis |
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A. occidentalis
A. clarkii
Aechmophorus is a genus of birds in the grebe family.
It has two living representatives breeding in western North America.
One prehistoric species has been described from fossil remains:
Although the two living species look very similar, bill shape and coloration, as well as feathering around the scarlet eye of the bird can be used to determine the precise species.
The western grebe has a straight bill with a dull green-yellow color as opposed to the Clark’s grebe, which has a slightly upturned, bright orange-yellow bill. In both species the male has a longer and deeper bill than that of the female, making it a distinguishing feature. All species of grebes display the pattern of lobed feet. A tough skin surrounds each toe separately, providing more surface area for effective swimming. This form increases the power of propulsion per stroke and reduces drag when the bird is recovering. Skeletal measurements taken from both species, when averaged together, revealed that for the most part the western grebe is larger than the Clark’s grebe. The two species also differ in their advertising calls. The western grebe gives a call that includes two distinct “cree-cree” notes, while the Clark’s grebe consists of a single “creeet” note, more drawn out.
Western North America is home for nearly all individuals of both species of grebes. When migration occurs, the birds in the northern range will travel west in flocks, at night to the Pacific coast. Both western and Clark’s grebes winter in sheltered bays or estuaries on the Pacific coast and summer in freshwater lakes with marshy vegetation as well as large open areas of water. The site of nesting is usually in a shallow water marsh. Both males and females help to build a floating platform nest of vegetation (Kaufman 1996). Because of the colonial nature of these birds nests must be continually guarded during the breeding season. If left unattended other pairs of birds seeking nest sites will seize the platform.
These two species, like most grebes, eat a diet consisting mostly of fish. They are also known to forage on crustaceans, insects, worms and salamanders. Foraging techniques are composed of a number of foot-propelled dives. Current research is associating the use of springing dives by the Clark’s grebe, in which the bird essentially leaps from the water before submerging, allowing it to reach deeper below the surface, with possibly proving niche separation between the two species.
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Wikipedia