this bird is about the size of a Lesser Goldfinch. It's very timid and all alone. Every time I think I know what it is, something just doesn't fit.
CLOSED: I give up........
Tough one! I'd like to see some better-focussed pics if you can get them. Leaning towards Chipping Sparrow, though it appears to have streaked flanks (which Chipping shouldn't!)
See .. if this feller, isn't your lil buddy in your photos ..
Lincoln's Sparrow Melospiza lincolnii >
http://www.enature.com/fieldguides/enlarged.asp?imageID=17346 .. & > http://www.enature.com/fieldguides/detail.asp?allSpecies=y&searchText=Lincoln
Altho' I've yet to find any info/resources that specifically mention [their] having a 'crest-like something' atop of their heads of which they can 'raise & lower' at will - - the Lincolns' do have it and use it frequently!
This same lil leary bird sure had me baffled, for the longest time also!