I have been studying this issue a lot since a pale redpoll arrived in my yard a couple of days ago with about 20 birds that I would call Common Redpolls. I have a couple of pics of the bird on my Flickr site and have concluded that it is a good candidate for male Hoary Redpoll: http://www.flickr.com/photos/9047968@N02/8328723156/in/photostream and http://www.flickr.com/photos/9047968@N02/8327663373/in/photostream/.
Unfortunately, after a brief appearance yesterday morning the bird has not returned. Despite the more wintery weather today there are no redpolls at all at my feeders, but I will update the list if this changes.
I first seriously pondered redpoll ID last Feb., after spending time in Fairbanks looking at a variety of birds. I summarized some of my thinking in this ABA blog post: http://blog.aba.org/2012/02/a-surfeit-of-redpolls.html, but I feel that the mystery bird in my yard has prompted more careful consideration.
My task in Fairbanks was made easier by location (where Hoary could be reasonably expected in winter) and by the presence of what I would call some "slam dunk" examples. The bird that came through my yard recently is not as obvious, but I believe a suite of traits point toward Hoary.
David Sibley has written many times on his blog about redpoll ID, and conveniently collated his redpoll posts here: http://www.sibleyguides.com/bird-info/common-redpoll-and-hoary-redpoll/. I have found several of his resources to be very helpful. In response to a reader's comment, he chimed in with what I think is a very interesting and pertinent comment:
A reader suggests that many people are not as conservative as perhaps they should be, and simply slap the "Hoary" label on any noticeably pale redpoll. I agree, but I also think that many true Hoarys are overlooked, so it may actually be that many birds reported as Hoarys are not, but an equal or greater number of real Hoarys are overlooked! (my emphasis.)
Among the strongest takeaways for me, he has addressed the bill issue. While the tiniest-billed Hoaries are easy to pick, they aren't all equipped with diminutive peckers:
What Seutin et al found is that specimens can be sorted by measurements, with pale (Hoary-types) having shorter bills by about 10% on average; means of 7.67 mm for dark birds and 7.01 for pale. Taking their mean for bill length +/- 2 standard deviations (I'm told this will encompass about 95% of all individuals) the bill measurements don't look so different:Common 7 – 8.2 mmHoary 6.5 – 7.5 mmIn other words, the differences are very slight, and there is extensive overlap, with the largest Hoary matching the average Common and the smallest Common matching the average Hoary. (my emphasis.)
I think my bird had a distinctly smaller bill than any of the other redpolls, a feature emphasized by the feathering extending down the maxilla a bit (which gives the bird a bit of a forehead bump, another good Hoary trait.) It doesn't, however, reach the wee extremes of my best examples from Fairbanks.
Sibley also summarizes a fantastic paper that included a Character Index for Redpoll Identification, which allows scoring individuals on a 1-6 scale for each of three traits: Flank streaking, Rump streaking, and Undertail Covert streaking. A 1 score in any category would be very dark and extensive, a 6 would be practically unmarked. (http://www.sibleyguides.com/2008/01/a-character-index-for-redpoll-identification/) Using the scale…
My photos don't show the rump Steve Mlodinow photographed it and it is very clean, perhaps a "5" on the scale. I'll not bias any of you wishing to score the pics for yourselves by giving you my score. I will say it isn't out at the end of the scoring bell curve, but I do believe it passes muster.Numerically, a male (pink breast) with a score from 14 to 18 was called a Hoary in Troy's paper, a score from 3 to 7 would be Common, and from 8 to 13 intermediate. For females and immatures (no pink) it only took a score of 11 or higher to qualify as a Hoary, since no female-type scored higher than 13, and a score of 3 to 6 indicated a Common; leaving 7 to 10 intermediate (I'm using the straight numbers, Troy adjusted so that the lowest score was 1).
You'll note that the index doesn't address bill size, mantle color, degree of pink, etc. In personal communications with Steve Mlodinow, who studied hundreds of redpoll specimens in the Field Museum (I think that was the institution but if not, I'll let Steve correct me), he found that the only consistent traits of the Hoaries were clean rumps and undertail coverts (though streaks on the longest undertail coverts of Hoaries were not uncommon.)
Moving on, Sibley gives a nice checklist of marks to look for when you have a candidate bird:
...check details in no particular order, depending on what part of the bird you can see well, and try to make direct comparisons with birds of the same plumage type:
- the scapulars should be paler with frosty whitish edges on Hoary
- flank streaking should be sparse and narrow on Hoary
- undertail coverts should be white or with only narrow streaks on Hoary (female Hoary often have narrow shaft streaks not as broad as on Commons, and male Common can have no streaks)
- rump should be mostly white on Hoary, whiter on males (but male Commons can also have a noticeably pale rump)
- the bill should look short and small, with fluffy nasal bristles covering the base of the upper mandible and making the forehead bulge a bit (but Commons also have tiny bills, you have to study some Commons at close range before you will feel confident using this feature)
- The pale edges on the wing coverts and secondaries should be broader and whiter on Hoary (but this is variable in both species and, as with all of these clues, it's important to compare birds of the same sex)
And also lists other more subjective features to consider:
Other features that have been mentioned and that might be worth watching for and testing (but many of these are very subjective and my impression currently is that these are less useful than the ones mentioned above):
- a smaller and brighter red "poll" on the forehead of Hoary
- less dark color on the throat and lores on Hoary: more restricted and not as dark (but appearance varies with angle of view)
- Hoary overall larger and fluffier (but note subspecies differences in size)
- neck appears thicker on Hoary
- fluffy "leggings" on Hoary
- A tendency for Hoary to raise tail when foraging on the ground
- relatively longer tail
- there may be subtle differences in calls, and this deserves more testing, but singling one calling bird out of a flock is usually impossible. The larger "Greenland" subspecies also may have different calls.
I think my bird meets each criterion in the first checklist and also fits bullets 1,2,and 4 on the second. If folks have other resources to share regarding ID tips for this potentially difficult separation, please share them with the group. Good luck in your redpoll searches, snap lots of shots, and have fun!
Happy New Year- Bill Schmoker, Longmont
______________________
• Bill Schmoker •
______________________
720/201-5749
______________________
On Dec 31, 2012, at 2:14 PM, Nick Komar wrote:
With reports of Hoary Redpolls surfacing on Cobirds and E-bird, I have been trying to get better looks at redpolls in the large flock hanging out at the east end of Lee Martinez Park and visiting the feeders at the Fort Collins Museum of Discovery which recently opened there. I photographed >10 individuals on 23 December and 30 December, and these photos are posted at http://www.pbase.com/quetzal/redpolls2012. I think I see one or two with small bills, and I think I see one or two with 3 or fewer streaked undertail coverts, and several that seem to approach Sibley's drawing of the southern Hoary Redpoll, but I lack confidence in identifying any of these as Hoary Redpoll. The photos show a tremendous variation, which makes me even less confident about identifying Hoary, and even suspicious that Hoary and Common may actually belong to a single species. Anyway, comments from others are welcome (probably would be appreciated by other list members also, so consider sending the comments to the listserve). I would especially be interested if you think any of these are candidate Hoary. If anyone has photographed a Hoary in Colorado, I would certainly like to see those photos.Nick KomarFort Collins CO--
You received this message because you are subscribed to the Google Groups "Colorado Birds" group.
To post to this group, send email to cobirds@googlegroups.com.
To unsubscribe from this group, send email to cobirds+unsubscribe@googlegroups.com.
For more options, visit https://groups.google.com/groups/opt_out.
No comments:
Post a Comment