Oh the agony!  But wait, there's more.  I managed to round up a few more 
photos.  This is the entire lot -- the good, the bad, and the ugly:

http://www.uvm.edu/~ebuford/birds/CE_Fall_warbler.html

Top vote-getters so far are bay-breasted and blackpoll.  What say you now?

Thanks for playing!
EB

Fred and Chris Pratt wrote:
> Well, you're right - with just these two photos a definitive answer 
> may not be possible.  For example, I am uncomfortable pronouncing the 
> back streaked (and therefore a Blackpoll or a Bay-breasted) or 
> unstreaked (and therefore a Pine).  Also, is the mantle a dark green 
> as the top photo suggests or almost yellow-greenish as the lower photo 
> suggests?  The latter color might push us towards Blackpoll (though 
> leg color isn't as pale or as orange as one would like for 
> Blackpoll).  Finally, the lower photo suggests a touch of buff or bay 
> on the flank (barely visible) which of course could close the deal for 
> Bay-breasted.
>
> Another interesting thing to note is the eye which seems to have 
> crescents rather than an eyebrow.  To me this is suggestive of a Pine 
> Warbler.
>
> If I saw this bird in the field, I am sure it would be readily 
> identifiable. However, if I were still on the Bird Records Committee, 
> I would be seeking to know how other members would respond to the 
> questions I have raised regarding the two photos.
>
> I guess I think the back is streaked - and therefore not a Pine - so 
> if a gun were at my head, I would probably go with a bay-breast.
>
> But who knows - maybe the poor thing is a Blackpoll!  Or maybe that 
> back isn't streaked after all.
>
> Pipit
>
> Ernie Buford wrote:
>> Here's a Fall quiz bird for you all.  I have my own guess plus an 
>> opinion from a member of the bird records committee, but be 
>> forewarned that there may not be a definitive answer.  All I have at 
>> the moment are these two photos:
>>
>> http://www.uvm.edu/~ebuford/birds/CE_Fall_warbler.html
>>
>> This bird hit a window in Bristol last week and was photographed by a 
>> friend of mine.  Which warbler is it, and why?  Give it a shot.
>>
>> Enjoy,
>> Ernie Buford
>>