The Clark's and Western Grebes were long thought to be of the same species. The Clark’s Grebe was first described to science in 1858, but was considered as a variant of the western Grebe. It was not until 1985 that the two species were split and the Clark’s gained its own species status.
Clark's Grebe, Aechmophorus clarkii: Bear River Bird Sanctuary; Brigham, Utah
Though they both perform the same style of courtship display and occupy the same habitat, the differences in facial patterns keeps the two species from interbreeding. The black cap of the Western Grebe extends to the eye, or below the eye while the Clark’s has a distinct white margin between the eye and black cap. I have also noticed, and this is easily recognized at a distance, that the Clark’s flankes seem to be lighter than those of the Western Grebe. This makes identification of the two species quite easy from afar.
Other identifying features are the bill color and the voice. The Clark’s bill is a bright yellow-orange, while the Western's shows a yellow bill with an olive tinge. The voices of the two species are quite different as well. The Clark’s voice is a single syllable “kreeek,” and the Western a distinct two syllable “Kree-eeek.”
Western Grebe, Aechmophorus occidentalis: Bear River Bird Sanctuary; Brigham, Utah
Note: that the two Western Grebes shown here shown different facial patterns. The
foreground bird shows the black cap extenuating to the top of the eye while the bird in
the background show the black cap extending below the eye.
Note: that the two Western Grebes shown here shown different facial patterns. The
foreground bird shows the black cap extenuating to the top of the eye while the bird in
the background show the black cap extending below the eye.
The Clark’s Grebe is named in honor of John Henry Clark. Clark was a 19th century American surveyor who was a naturalist and a collector. The genus name Aechmophorus comes from the Ancient Greek word “aichme”, meaning spear, referencing the grebes long dagger like beak.
Hear the call of the Clark’s Grebe:
Hear the call of the Western Grebe: http://www.allaboutbirds.org/guide/Western_Grebe/sounds
References: https://en.wikipedia.org/wiki/Clark's_grebe
Top: Nikon D800, Nikkor 500mm f4, 1/200 second @ f/6.3
Bottom: Nikon D800, Nikkor 500mm f4, 1/400 second @ f/10
No comments:
Post a Comment