Sean Fitzgerald reported a frosty male Hoary Redpoll near the Celebration Cinemas at Knapp and E. Beltline on Thursday amongst about 200 Common Redpolls foraging in a weedy vacant lot. Within 5 minutes the entire flock had disappeared. Follow up chases found only a smaller flock of about 70 birds, which included an interesting Redpoll (perhaps 2) which was clearly paler than the rest of the flock suggesting Hoary, but also had a few characteristics which looked right for Common Redpoll as well. First, the Hoary marks: paler underparts including limited flank streaking and no noticable streaking on the undertail coverts, pale white rump lacking noticable streaking, very limited pink blush to the breast. Common features: cap large and approaching the bill as closely as those of other Commons, scapulars lacking white edges, secondary and tertials not having noticably wider white edging than Common, no obvious "bull-headedness" to the forehead. Indeterminate marks: bill at times looked just like neighboring Commons, but at other times seemed a bit smaller and more pinched in. Here are my best photos of the bird.
with Commons for comparison of overall color, secondary and tertial edging, etc.
and lastly, a nearby Common Redpoll
Now, what are we to call my mystery bird? Pyle (1997) indicates that some Common Redpolls may appear to be intermediate between the two species, and that hybrids are not yet known but are expected to occur. There are also 2 subspecies of each species which can occur here, as well as extensive variation in the four age and sex classes.
Sibley's blog and links therein provide an excellent summary of Hoary Redpoll ID. He surmises that after first locating a pale individual within a flock, you should proceed to look for any of 6 characteristics which should all or mostly line up before you call your bird a Hoary. In my case, the pink on the breast should establish the bird as a male (although Sibley fails to mention Pyle's (1997) comment that some adult females may occasionally show pink here). Three of Sibley's six characters (sparse flank streaking, no streaking on undertail coverts, rump mostly white) line up with Hoary, two with Common (scapulars and wing coverts and secondary edging), and one indeterminate (bill).
In my assessment, we simply do not have enough to call this bird a Hoary, so I am leaving it unidentified. Although this bird could be a hybrid, it may well be within the normal variation for Common Redpoll (scary, huh?), a fact which underscores the need for a high level of scrutiny and conservatism in IDing redpolls.
I'm holding out for a bird showing 5 or 6 of Sibley's characters for Hoary. With recent reports of this fall's upper peninsula Hoary Redpoll stock having largely cleared out over the last week or two (per Skye Haas), it's possible we'll have plenty of chances this winter!
Lastly, for comparison of my birdwith a good female Hoary from Indiana Dunes State Park this week, see PGrubes's Flickr photos. Note particularly the bill and face structure and size of the "poll