I've change my identification of this bird from Downy to Hairy. I initially chose Downy because I thought I saw the "conspicuous tuft of nasal bristles" that Sibley mentions in his guide. I missed the lack of black marks on the tail feathers and the proportion of the bill. When I first saw it I thought it was a Hairy because it seemed larger than I expected for a Downy. Even identifying a common bird requires observing as many details as possible and not giving too much weight to any one factor. Thanks to Nathan for helping with this ID.