This very odd Song Sparrow turned up along the roadside about 1/3 of the way between High Pines and the 3rd crossover. This photo shows the oversized, grosbeak-like bill as well as essentially bald head including wispy feathers and the dark coloration.

UPDATE: I queried Marshall Iliff of eBird and learned that "baldness" creates some very strange looks including what is going on with this bird. There are numerous photos of "bald" Cardinals at this site: http://tinyurl.com/medpsll. And so I guess the question is not what's going on, but why..... and without having the bird in hand one can't know. I have read since learning this, that baldness in birds is often caused by mites and eventually they go and the feathers grow back. I hope that's the case for this bird.