I had a few hours to kill Sunday after I arrived at my hotel in San Francisco so I took the #19 bus up Polk to Fort Mason Park. That proved to be a wise decision. I was looking for Cherry-headed Conures (the birds made famous by The Wild Parrots of Telegraph Hill) but I almost immediately found a native life bird instead: Clark’s Grebe. This bird is very similar to the more common Western Grebe. The difference is whether the dark head feathers extend downward to encompass the eye or not. Normally you’d need a scope to tell for sure, but there were several birds close enough to ID with binoculars alone.  Another field mark: all the birds showed more white on the body and less black than you’d expect with a Western Grebe. Furthermore one bird had a bright yellow bill rather than the dingier bill you’d expect on a Western. However, the eye is really definitive. 

Annoyingly some of the birds had an eye right on the border, which isn’t supposed to happen at this time of year. However there wasn’t enough black around the eye to turn any of them into a Western, and they did look more like a non-breeding Clark’s. Barring something weird like a hybrid Western-Clark’s, I think all the grebes I saw yesterday were Clark’s, and at least one of the birds hit all the field marks for a Clark’s dead on.
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