[CT Birds] Shades of Hoary-ness?
rmharvey at snet.net
Tue Jan 1 20:10:33 EST 2013
I was one of the many today who pursued the Hoary Redpoll that Dave Rosgen had in his yard yesterday. Shortly before I left Dave came out and provided a bit more background information on his sighting. He had been seeing a very white redpoll for a couple of days before getting good enough looks to identify it conclusively as a Hoary Redpoll. He was viewing it from indoors, looking down, and among the field marks he verified was the white rump. One of this neighbors farther down the street also has had such a bird visiting her feeders, though not as thoroughly described as far as I heard.
There were three birds I saw (or was present while others saw) today that were candidates for Hoary Redpoll. The first was seen briefly right after Tina Green and Sara Zagorski arrived, and was quite light. I tried very hard to see the rump, but was unable to. The upper back was quite frosty, frostier than any bird I saw later. Nothing seem about this bird contradicted it being the same bird Dave saw yesterday and described today.
The second was seen much longer by many more birders; some photos were taken and the bird was much discussed. I am certain, as I believe were Tina and Sara, That this was not the same bird as seen earlier. It was not as white as the first bird. However the pictures were suggestive and Jay Kaplan made a pretty good case for it being a possible Hoary (without committing himself). While I did not see the rump on that bird either, I did get good and long looks at the undertail coverts and did not see any streaking or marking at all - and I was looking hard for it.
The third bird appeared a bit later and did not stay long, but several who saw it talked about how very white it was and some talked about how large it appeared. I never got on that bird. The descriptions I heard were in line with the possibility it matched Dave Rosgen's bird and/or the first one I saw with TIna and Sara.
One thing that became obvious as different flocks arrived and departed was that there were multiple flocks visiting the feeder. One flock in particular had no birds white enough to generate that I've-GOT-to-get-a-better-look-at-THAT-one response; the birds were overall darker with more males, more red. Every earlier flock has at least one lighter bird.
Early this evening I looked up some articles on the web on identification of Redpolls. I started with articles by David Sibley, and followed links he provided to articles by others. By no means I have I assimilated all this information, but some points stood out to me.
First, there was this Sibley article: http://www.sibleyguides.com/2011/02/four-redpoll-taxa-in-one-photo/, "Four redpoll taxa in one photo". The photo is taken from a more extensive collection of photos with a lot of discussion, which Sibley links to (http://northshorenature.blogspot.ca/2011/01/hornemanns-hoary-and-greater-common.html). The key slap-in-the-face from that photo is the second Hoary Redpoll - marked as type 4 in the linked article and fourth from the left in that particular photo. That rear view does not jump out at me as a possible Hoary, despite the rule of thumb I have heard that Hoary stands out.
Second, there was another Sibley article: http://sibleyguides.blogspot.com/2008/01/character-index-for-redpoll.html. This is an analysis of data from a paper from 1985. Cherry picking a few bits that seem pertinent...
- As per Sibley's comment # 1, "The most interesting observation in the whole paper, I think, is the fact that all redpolls from study sites in the taiga (boreal forest) were dark (low-scoring) Common-types. No intermediate or Hoary-types were found at those sites. At tundra sites most redpolls were either intermediate or Hoary, with small and variable numbers of dark birds scored as Commons." (There is more, see the article.) This, combined with the one exclusively dark flock we saw, makes me wonder if the boreal forest population tends to flock together.
- As per Sibley's note # 3, "streaking on undertail coverts, rump, and flanks - are all related, so combining all three is probably not much more powerful than using a single one." While I did not get a look at any white rumps today, I do believe I had good looks at the undertail coverts of the second bird I mentioned and saw no signs of streaking.)
- As per Sibley's note # 4: "So there is a slight tendency for pale Hoary-types to have shorter bills, but it should not be emphasized as a field mark...". We spend a lot of time today talking about subtle bill size differences.
While my incomplete review of these articles left me about as confused as before, I think it is reasonable to ask whether there could be at least two Hoary Redpolls around Laurel Way in Winchester, one showing the characteristics of the more extreme white subspecies, and another those of the less obvious alternative.
In any case, it was a great day to watch and study redpolls and see friends. Thanks to Dave Rosgen for providing such an effective collection of feeders, and allowing so many of us to view them.
Beacon Falls, CT
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