Greetings... two more tough birds! I think these two are in the "BayPoll" 
set with 9a checking in as a HY bay-breasted warbler and 10a a HY(?) 
blackpoll. If the feet on 10a were obscured, it would be a tougher call, 
because a good way to separate bay-breasted and blackpoll warblers is by leg 
color: bay-breasteds usually have dark or gray-colored legs and blackpolls 
have yellowish legs, except for some HY blackpolls which sometimes have 
entirely dark legs, with the exception of the bottoms of their "feet" which 
are always yellow, even if the legs and the top of the feet are dark. The 
clear-breasted look of 9a, the faint eyeline, as opposed to what I imagine 
to be the slightly darker eyeline on 10a and the streaked breast on 10a also 
seem like good clues to me. Bay-breasteds have buffy undertail coverts, 
while blackpolls have white undertail coverts. I think I see that contrast 
in the two undertail hint photos. Having said that . . .  sometimes you just 
have to call these things "BayPolls" or shrug your shoulders and admit you 
just don't know.

What makes me a little cautious is that I know you guys have pine warblers 
in the Hueston Woods area--I never encounter that species here in the Mill 
Creek valley where I do almost of all of my fall birding. But neither bird 
looks right for a pine to me.

I put together a chart five years ago using sightings reports from Ned 
Keller's Birding in Cincinnati Bird Sightings Database for thirteen of the 
warbler species we get as common migrants in the fall. (Something I doubt 
I'd have time to do today with two small kids to chase around!) I broke down 
the number of sightings for each month by "week" periods. It's not 
scientific, but I think it gives a sense at least of the abundance in our 
area of bay-breasted and blackpoll warblers. It's interesting to see the 
disparity in reports of blackpolls versus bay-breasteds during fall 
migration. Throughout the fall in the Cincinnati-area, bay-breasted reports 
outnumbered blackpoll reports by about 3 to 1 at the time I put the chart 
together. These are merely reports of either species collected over a period 
of 10+ years; sometimes (most times) the reporters don't provide numbers of 
individuals. So it's not meant to be total numbers of birds, but rather the 
number of reports of each species. Here's a quick breakdown:

August week 4: 10 bay-breasted : 2 blackpoll
Sept. wk 1:    31 BBWA : 10 BLPW
Sept. wk 2:    31 BBWA : 10 BLPW
Sept. wk 3:    28 BBWA : 13 BLPW
Sept. wk 4:    28 BBWA :  10 BLPW
Oct. wk 1:     13 BBWA :  5 BLPW
Oct. wk 2:     10 BBWA :  3 BLPW

I'd be interested in hearing what sort of ratios Bill Buskirk finds in the 
Whitewater Valley or what birders in other places in our area find. I would 
bet the further north you go in the region, the more blackpolls you find, 
given their rather straightforward eastward migration route out of their 
breeding grounds. It will be interesting to see how Dave and Jill's banding 
results for the two species turn out as the years go by.

If you get a chance to bird along Lake Erie in the fall, you see many more 
blackpolls than we get down here. There's a chapter in a book called 
"Migrations of Angels" about blackpoll warblers that is fascinating to read. 
In fact, the whole book is good reading. A number of ornithologists chipped 
in chapters on different migration topics, including sandhill cranes, rufous 
hummingbirds, the importance of Gulf Coast habitats for migration staging, 
the crazy trek of blackpolls eastward across the northern US and southern 
Canada to the US northeast coast, into the Atlantic, and nonstop over 
Burmuda to South America, etc. The little butter balls fly over the Atlantic 
for upwards of 100 hours straight to reach South America. Amazing stuff. 
Makes you want to put down the book and go study zoology and ornithology, 
which some of you are already lucky enough to be doing!

Take care,
---Mike Busam
Schumacher-Dugan, OH