Hi Luke,
It is a very complex issue . . .
Of redpoll taxa currently accepted, there's two wide-range forms:
flammea - Common Redpoll a.k.a. Mealy Redpoll: circumpolar subarctic, eastern Canada west across N America & northern Eurasia to Norway
exilipes - Hoary Redpoll a.k.a. Arctic Redpoll: circumpolar arctic, eastern Canada west across N America & northern Eurasia to Norway; currently treated as a race of
hornemanni but may actually be more closely related to
flammea than it is to
hornemanni.
and four restricted-range forms:
cabaret - Lesser Redpoll: Britain & central Europe; recently split from
flammea to be a species in its own right, though some dispute this and say it should be retained in
flammea as a race.
rostrata - Greenland Redpoll: Greenland & Baffin Island (Canada); currently treated as a race of
flammea, though this has been disputed, it may be closer to
hornemanni than to
flammea.
islandica - Iceland Redpoll: Iceland endemic; currently treated as a race of
flammea, though this has also been questioned, may be more related to
hornemanni.
hornemanni - Greenland Arctic/Hoary Redpoll: Greenland, Baffin & Ellesmere Islands (Canada); currently including
exilipes as a race, though as said above, open to dispute.
In CT mostly you'll be getting
flammea, but the occasional wintering
exilipes, rostrata and
hornemanni could all occur rarely.
There's been a few recent threads here on BF that might be worth reading through - let us know if they help out, or just confuse you even more!
http://www.birdforum.net/showthread.php?t=10037
http://www.birdforum.net/showthread.php?t=10725
http://www.birdforum.net/showthread.php?t=7540
Oh, and just to make things more difficult - there's (probably) some individuals of all the races which are impossible to identify. The range of characters overlaps between (probably) all of them. There's even some evidence to suggest, as with crossbill identification, that even DNA tests cannot be relied on to distinguish them . . . :h?::h?: :h?:
Michael