These birds are an interesting study in identification and misidentification. I initially identified them as just two of the 1000+ Eared Grebes that were on Mono Lake at this time but it was pointed out to me (Thanks Jim!) that they just looked odd and I realized that with their white cheeks, flat crown, and smoothly curved back (not fluffed) these looked much closer to Horned Grebes than Eared. Horned Grebes are exceptionally rare on inland lakes in the fall and something about these two birds inspired me to do even more research.
I consulted several field guides including National Geographic (6th ed.), Sibley, Kevin Zimmer's guide to birding in the American West, and Don Roberson's website on the most misidentified birds in Monterey County.
I strongly believe these birds to be 1st fall Eared Grebes (birds that hatched this year). According to these sources, first fall birds can show a much whiter face than adult birds at the same time of year, and unlike horned grebe whose white cheek is a clearly demarcated line just below the eye, these individuals show distinct smudginess with some grey in the auriculars (visible at larger sizes).
The bill also is more Eared-like than Horned. On the bird in the foreground, at large size, it shows a slight upturn to the edge of the lower mandible unlike the slightly downturned bill of the Horned Grebe. Horned Grebes also generally have white tips to their bills while the bill tips on Eared Grebes are generally dark.
A Horned Grebe with this much white in the face would almost certainly show a whiter neck, while the bird in the foreground clearly has a "dirty" looking throat. Lastly, the bird's overall shape is much sleeker than one normally associates with Eared Grebes, but these individuals were part of a group that were actively diving and feeding; activities that can lead to a more streamlined appearance.
Big thanks Jim for making me take a critical look at these birds! And thanks to Don Roberson for designing and hosting such an informative website
The bird list from this outing can be found here:
The black-necked grebe (Podiceps nigricollis), known in North America as the eared grebe, is a member of the grebe family of water birds. It occurs on every continent except Australia and Antarctica.