This past Sunday, I had a very pleasant experience … two experiences at once, actually. One was spending the morning in my local turf with a posse of great birders, including Birding magazine editor Ted Floyd.
Left-to-right: my big mug, Shawn Chandler, Danny Akers, Amar Ayyash, Andy Sigler, Ted Floyd, Joel Greenberg.
At William W. Powers State Recreation Area, on the far south side of Chicago.
The other was having as much time as we wanted with an unbelievably cooperative pair of Hoary Redpolls. This is a species that is very rarely found as far south as Chicago. When they are found, it is often at a feeder, and while solid, identifiable looks and photos are to be had, feeder frenzy often has the birds moving around a lot.
For the past 10 days or so, there has been a flock of about a dozen Common Redpolls feeding in a small grove of alders lining the frozen shore of Wolf Lake, on the far south side of Chicago. When the birds were first discovered by Andrew Aldrich and Joshua Little, a few pictures were posted to the Illinois Birders’ Forum. After a little discussion, it was agreed that the bird they photographed was a Hoary Redpoll. In the days following, there was a bit of confusion when other birders who went to look for it found the bird (or did they?), but the ID wasn’t as straightforward as Joshua and Andrew’s photos made it seem.
It turns out that there are 2 Hoary Redpolls in this small flock! Sunday morning our group of seven found these birds and they were feeding low, mostly at about eye-level or lower, and seemed to be hell-bent on giving us the best looks and comparisons possible. Of all the birds there, the two Hoaries seemed to make a point of being as close to the birders as they could be, and I was able to take over 700 pictures of them. It was wonderful.
As we examined them, something very interesting became apparent: the “hoarier” bird—meaning the one that is most noticeably pale and frosty—has markings on the undertail coverts and rump that put it right at the edge of being “good”. The streaks on the flanks are also just a bit heavier on this bird. The other has perfect markings (or lack thereof) on the rump, undertail coverts and flanks, but is noticeable darker and browner that the first.
We will call the first (paler and frostier) bird HORE A, and the other HORE B:
Click images to view full-screen.
Left: HORE A; right, HORE B.
As you can see, there’s quite a difference between these two in overall color and tone. Now let’s take a peek at the undertail coverts…
Left, HORE A; right HORE B
Not what you were expecting, huh?! Typically, the paler the redpoll, the less marked the rump and undertail coverts, at least that’s how the field guides tend to show things. In fact, depending on the guide you’re referencing, HORE A could be (should be?) a Common Redpoll. But there’s no denying that the upperpart coloration and flank streaking look better (perfect, in fact) for Hoary, than Common.
Our current understanding of redpolls, and what separates Common from Hoary, has generated reams of paper and taken up terabytes of disk space. But genetic studies being conducted by Nick Mason and Scott Taylor at Cornell University may change the way we define these birds. In short, they suggest that currently recognized species of redpolls have not experienced prolonged periods of isolation followed by secondary contact, which is characteristic of hybrid zones between divergent species, such as Black-capped and Carolina Chickadees; in other words, redpolls may be better considered a single species with pronounced phenotypic variation rather than multiple species. The subject was touched upon two years ago here on this blog by Andy Boyce.
But for the moment, let’s just take some time to appreciate the details of these wonderful little birds.
