Clark's Grebe, Aechmophorus clarkii |
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![]() Clark's and Western Grebe were long considered two forms of the same species; only recently were they recognized as separate species within the genus Aechmophorus. The picture below shows a Clark's behind a Western, illustrating the standard distinguishing marks: Clark's has an orange rather than a greenish bill; its dark crown ends above the eye, especially in breeding plumage; and it tends to have lighter colored flanks. |
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![]() Clark's Grebes with a fish, above, and a mole crab, below. |
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![]() Both Clark's and Western Grebes normally nest in large colonies on freshwater lakes in the interior of western North America. A pair of Clark's surprised local birders in 2011 by nesting on a small nearshore island in an artificial saltwater pond in Mountain View, bordering on southern San Francisco Bay. Below are the two together, with a newly-hatched chick riding on the back of one of them; above is the other adult incubating the remaining unhatched egg on the nest. Both Clark's sexes incubate equally, but while adults of both sexes carry the new chick ("back-brood") in the fashion shown below, the male does so more frequently, and the adult back-brooding the chick in this picture had a distinctly longer bill, consistent with it being the male. Sadly, the nesting effort failed; the single chick shown below died shortly after this picture was taken, and no other chick was observed to have hatched. |
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![]() In 2012, a pair of Clark's Grebes, possibly the same pair as in 2011, again attempted to nest on the same island, also unsuccessfully. Above, the pair swimming together in their courting ritual in May; below, the pair with two eggs in their nest in July; the eggs never hatched. | |
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![]() Continuing the drama of failed attempts at nesting in the Bay Area, in Spring 2013 this pair of Clark's Grebes built a nest at Coyote Lake in southern Santa Clara County, as did several pairs of Western Grebes. Above, courtship with one bird carrying nesting material; below, bird sitting on nest with other bird bringing food or nesting material. The nests were ultimately abandoned, and no hatchlings of either species were ever seen. | |
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![]() Above, three adult Clark's Grebes, possibly two males flanking one female and competing for her attention, in a lagoon on the eastern shore of San Francisco Bay in March 2015. Bill size and shape provide the only moderately reliable feature distinguishing the sexes in the Clark's/Western complex; the bill of the male tends to be longer and thicker than that of the female, and can have a convex upper mandible where the female's is more often straight, sometimes with an apparent slight up-tilt. | |
![]() Above, one of two adults, likely a pair, splashing water on the other; below, the same two swimming nearly parallel with curved necks. This looks like the start of the famous rushing ceremony, in which Aechmophorus grebes -- either a courting pair, or two competing males -- appear to run alongside each other over the water. In this case, no full rushing display eventuated. I had seen and been able to photograph the display performed by two Western Grebes in the April 2013 at Coyote Lake in Santa Clara County, shown here. | |
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