Categories
Uncategorized

The Redpoll Complex: Redpolls, redpolls, redpolls…….and the usual cautionary tales.

By Matthew A. Young:

One of the things we, the Finch Research Network (FiRN),  plan to do for the birding and ornithological communities, is to help with tough finch identifications, and there’s perhaps no tougher species group than the redpolls. Again, we’re super excited to have Alex Lamoreaux  join the team at FiRN to help with identifications for such species as Hoary Redpoll, “green morph” Pine Siskin, and more. 

Much of the below photo essay was written in March 2013 for Birding Frontiers but remains quite relevant whenever or wherever redpolls irrupt. It’s been updated, added to, and adapted for the Redpoll irruption 2020-21. 

A fairly large wide-scale invasion of redpolls took place in 2012-13 and it’ll be interesting to see how this invasion 2020-21 matches it. What was unusual about the 2012-13 invasion was that it happened in both the eastern and western parts of the United States, which looks like might be happening this year too! Often invasions only occur in either the east or west, not both at once. By January of 2013, Colorado had seen more redpolls (both species) than they had seen in 25 years combined. In the northeastern United States, more Hoary (Arctic) and “Greater” (Northwestern subspecies islandica/rostrata) Common redpolls were being reported than usual. 

The most familiar Common Redpoll (Acanthis flammea) subspecies across the circumpolar areas of the globe including North America and Eurasia is the “flammea.” subspecies. There’s also the “Greater” Common Redpoll, also known as the “rostrata” subspecies, which is endemic to Greenland. Meanwhile, many birders have heard of the pale Hoary Redpoll (Acanthis hornemanni), also known as the Arctic Redpoll, with the exilipes subspecies found in North America and Eurasia across the extreme Arctic and the hornemanni subspecies endemic to Greenland. For the ease of reading , I’ll refer to these birds as the “ssp. flammea Common Redpoll,” “the Greater Common Redpoll,” “Hornemann’s Hoary Redpoll,” and “ssp. exilipes Hoary Redpoll.” “Hornemann’s Hoary Redpoll and the Greater Common Redpoll are a good bit larger overall than most “ssp. exilipes Hoary Redpoll” or ssp. flammea Common Redpoll.

In the small upstate New York city of Cortland, I had the luxury of having redpolls visit my feeders starting mid-December. As any redpoll enthusiast will do, I started my usual painstaking examination of each and every bird. As most know, the variation found in the different redpoll subspecies can throw even the best of the best birders into a state of frustration. At first the variation found in the flock in my backyard was fair at best, but that all changed on Sunday 20th of January 2013 when a new flock appeared… and the variation was nothing like I had ever seen before.

This “new” flock had several very obvious Hoary type birds and a few Greater Common Redpoll type birds. But as I looked closer and closer, I realized there were some birds that were hard to ID… at least one bird seemed to be large and white enough for the Hornemann’s Hoary Redpoll… and another I kept looking at over the next 3+ weeks just didn’t seem to quite match that of any of the known North American subspecies. The rule with Redpolls is to take your TIME.  Many are, but some are not an instant ID. They need to be seen and studied, mulled over and over again, photographed at as many angles possible, discussed, and then often, but not always,  a clear identity will emerge.

Here are several photos of various birds seen in my yard or my neighbors yard (i.e. listed as Cortland, NY) and a few other pics from different areas of the northeastern United States to add additional context.

Photo 1. Male and female ssp. flammea Common Redpolls. Photo Patrick Tanner Cortland, NY February 2013.
Photo 2. A typical male ssp. flammea Common Redpoll. Photo Jay McGowan Cortland, NY February 2013.
Photo 3. A ssp. exilipes Hoary Redpoll. Bird has frosty edging to mantle and back of head, moderately small bill, ochre wash to face and upper parts, and wispy flank streaking. Undertail clean, and rump looked clean. This particular individual is quite buffy, which isn’t unusual in female type birds. Photo Luke Seitz Cortland, NY February 2013.
Photo 4. Here’s a male ssp. exilipes Hoary Redpoll. Light hint of rose to upper breast, small bill, clean undertail coverts and frosty edging to back of head and mantle. Photo Jacob Spendelow Minnesota February 2013. For more photos of Hoary Redpolls see Jacob’s superb website here.
Photo 5. Second port from bottom on right looks like a fairly good immature ssp. exilipes Hoary Redpoll with the rest being ssp. flammea Common Redpolls. Bird looks a little long billed and the flank streaking fairly strong, but fits within the Hoary Redpoll range. Some might disagree, but that’s redpolls. Photo Jay McGowan Ithaca, NY January 2013.
Photo 6. A relatively heavy and dark flank streaked ssp. exilipes Hoary Redpoll. Undertail and rump look clean, flank streaking is on heavier side. The mantle is frosty and wing bar wide and white. Bill is hard to see, but it looks quite small. It’s great to learn to look at redpolls in less than optimal conditions such as in this pic where the face of the bird is partly concealed. Photo Andy McGann Ontario, Canada February 2013.
Photo 7. Here’s a second and different ssp. exilipes Hoary Redpoll. Bird has wispy flank streaking, very small bill, and frosty-ish brown colored back. The mantle of ssp. exilipes birds often has a brownish-white or gray-white appearance – the frosty edging gives it this look.  The mantle on the back of Hoary Redpolls gets darker as you head towards spring due to feather wear. This photo was taken in February. See next photo for more of the same bird. Photo Andy McGann Ontario, Canada February 2013.
Photo 8. Same bird as above photo but is showing a different posture — ssp. exilipes Hoary Redpoll female. Nice white rump and looks to have clean undertail coverts too. Photo Andy McGann Ontario, Canada February 2013.
Photo 9. A very controversial bird but is quite possibly an immature female ssp. exilipes Hoary Redpoll, but this bird will surely cause divisions in the ranks. These kinds of individuals should not just be classified as “Common Redpolls” because they don’t fit a “classic Hoary look” — they are often best left as redpoll sp. Many would probably call this a Common because it’s not a “classic” looking bird. Bird stood out when seen live next to other birds, but again is a bird that many will fall on different sides of the ID line… mantle was moderately frosty, three thin undertail streaks, wispy flank streaking, but bill does look on the larger size.
Tom Johnson Cortland, NY February 2013.
immature female ssp. exilipes Hoary Redpolls are the hardest to identify. See here for very likely immature female ssp. exilipes Hoary Redpolls in Macaulay Library: https://macaulaylibrary.org/asset/92968121 or https://macaulaylibrary.org/asset/181198861
Photo 10. A female Hoary Redpoll, ssp. unknown (flying away). Notice very large white rump.  Many thought it was a ssp. hornemanni Hornemann’s Hoary Redpoll. Photo Jay McGowan Cortland, NY January 2013.
Photo 11. Thought to be the same bird as above (in center with legs up). Notice chunky size and completely white undertail coverts. Photo Jay McGowan Cortland, NY January 2013.
Photo 12. A female Hoary Redpoll. This bird appeared to be extremely white and large (suggesting ssp. hornemanni) with a snow-white rump and clean undertail. Mantle is very frosty and the bill perhaps stubby but broad? Photo Jacob Spendelow Cortland, NY February 2013.
Photo 13. Thought to be the same bird as above bird. Photo Patrick Tanner Cortland, NY February 2013.
Photo 14. Thought to be the same bird as above — A female Hoary Redpoll. The bird is slightly fluffed up in this pic, making it look even whiter and larger, thus making it look even more like ssp. hornemanni.  Photo Luke Seitz  Cortland, NY February 2013.
Photo 15. Yet again thought to be the same bird as above — A female Hoary Redpoll, suspected as ssp. hornemanni. We’re looking at the other side of the bird in the photo. Photo Jay McGowan Cortland, NY February 2013.
Photo 16. Very likely the same bird as in the next 3 pics (different individual than in preceding photos). Looks quite large. Clearly an Hoary Redpoll, but which subspecies? It looks quite a bit larger than other the birds in the photo strongly suggesting ssp. hornemanni. Photo Luke Seitz Cortland, NY February 2013.
Photo 17. Hoary Redpoll. Belly looks full with a bit of a no-neck appearance. Photo Luke Seitz Cortland, NY February 2013.
Photo 18. Hoary Redpoll. The same bird as above, but with this angle the bill doesn’t look quite as broad? Different angles are notorious for making the same redpoll look larger, whiter and/or broader billed. You need to get many looks. Photo Luke Seitz Cortland, NY February 2013.
Photo 19. Hoary Redpoll. Very likely same bird as above 3 pics (bird is facing right back center). Bird looks longer and larger and bill broad. Photo Luke Seitz Cortland, NY February 2013.
Photo 20. Bird facing forward back center — Greater Common Redpoll ssp. rostrata. Bird is large with several rows of dark flank streaks. Black bib is usually quite extensive like on this bird as well! The longer black bib when seen face on can often give bird a ghoulish appearance. Photo Andy McGann Ontario, Canada February 2013.
Photo 21. Greater Common Redpoll ssp. rostrata. Bird was noticeably larger when next to other birds, but unfortunately good pics with adjacent birds eluded us. Notice the several rows of dark flank streaks and swarthy brown mantle color. Photo Tom Johnson Cortland, NY February 2013.
Photo 22. Greater Common Redpoll ssp. rostrata. Again, bird is large with dark flank streaks and swarthy brown mantle color. Photo Graham Montgomery DeRuyter, NY March 2013.
Photo 23. Greater Common Redpoll ssp. rostrata. Very very swarthy brown colored bird! Bill also broad and with slightly convex upper mandible. Photo Andy McGann Ontario, Canada February 2013.
Photo 24. Greater Common Redpoll ssp. rostrata. This bird really has that ghoulish appearance. Photo Linda Salter DeRuyter, NY February 2013.
Photo 25. Same bird as above. Bird is at bottom center — Greater Common Redpoll ssp. rostrata. Photo Linda Salter DeRuyter, NY February 2013.
Photo 26. The front bird looking left is an Hoary Redpoll, ssp. exilipes. The bird in the back right looking left is an obvious Greater Common Redpoll, ssp. rostrata. The bird in front of this one is probably another Greater Common Redpoll, ssp. rostrata. The bird in the back left looking left is a Common Redpoll, ssp. flammea. Bird in front left looking left looks to be a Hoary Redpoll Photo John Wyatt and Debbie Ryan Winterport, Maine March 2013.
Photo 27. Greater Common Redpoll ssp. rostrata right (very likely same bird as in above Cortland, NY photo 21). The bird on the left is possibly the presumed ssp. hornemanni Hornemann’s Hoary Redpoll (perhaps same bird as in next photo). Both subspecies are larger than typical subspecies seen in North America –they looks about the same size as you would expect. Photo Jay McGowan, Cortland NY February 2013.
Photo 28. “Presumed” ssp. hornemanni Hornemann’s Hoary Redpoll (perhaps same bird as in above photo). Photo Patrick Tanner Cortland, NY February 2013.
Photo 29. There are 3 different subspecies of redpolls present here. Here’s the same “presumed” ssp. hornemanni Hornemann’s Hoary Redpoll as above near pole with definitive ssp. rostrata Greater Common Redpoll back near fence. Other birds are ssp. flammea Common Redpolls. Notice the size differences. Photo Patrick Tanner, Cortland, NY February 2013.
Photo 30. This photo is a duplicate photo of a ssp. exilipes Hoary Redpoll already used in Photo 3, but is provided again as a chance to perhaps examine differences in size and posture of the two ssp. of Hoary Redpolls? ssp. exilipes Hoary Redpolls almost always look like whiter Common Redpolls – they are basically the same size with the same structure, whereas Hornemann’s type birds, always seem to look bull-necked, hog-nosed and beer-bellied structurally.
Photo 31. The bird to focus on here is the bird in the front to the extreme right (The other two redpolls near center of screen are Hoary Redpolls). I saw this bird several times over the 3-week period and I never knew quite what to call it. It always looked a bit frostier and a bit bigger than any of the other Common Redpolls, but it had a weird strong fawn color throughout including the mantle; and overall was browner in wing color than the other birds. The bill shape and color never looked like a good match for ssp. exilipes Hoary Redpoll, which I did try to turn it into several times. Photo Andy McGann Cortland, NY February 2013.
Photo 32. Here’s the same bird as above front right. Look at how the flank streaking is quite dark and extends to rear flanks, which is again unlike most Hoary Redpolls. Photo Andy McGann Cortland, NY February 2013.
Photo 33. Again, same bird right of center. Photo Andy McGann Cortland, NY February 2013.
Photo 34. Here’s the same bird center right looking right. Hint of rump looks white, wing color brown, back a fawn color, and upper mandible perhaps concave. Photo Andy McGann Cortland, NY February 2013.
Photo 35. Same bird in center shaking itself and showing us a whitish rump. Photo Andy McGann Cortland, NY February 2013.
Photo 36. Once again, same bird front center looking away. Bird is frosty but with fawn mantle color, white rump, and dark flank streaking extending to rear (darker and thicker actually towards rear flanks). Bird seemed to always be hanging with the Hoary Redpolls in the flock.

We only introduced four subspecies of Common and Hoary redpoll… but there’s another we didn’t mention, the islandica species of the Common Redpoll. In eBird ssp. islandica is lumped in with rostrata as islandica/rostrata. Is the bird from photos 31-36 perhaps of this subspecies? Well-known redpoll expert, Andy Stoddart examined these pics and said the following:

“is long-bodied, rather plain and buffy around the face, a strange grey-fawn colour above and well-streaked on the rear flanks but on a clean white background. It seems to share characters of both ‘Hoary’ and ‘Common’ type redpolls. I agree that it doesn’t look like ssp. flammea, either in terms of size or plumage….. so what is it?
If it really is as large as it looks (more on this below) I think there are only two real possibilities – a pale ssp. ‘islandica’ of the well-streaked ‘mid-range’ type or (if such things exist at all) a hornemanni/rostrata hybrid. Of course some islandica may look as they do because of gene flow between a dark and a pale form so the two scenarios are not that different. I’ve not heard of any confirmed hornemanni/rostrata hybrids, though there is a mention in the literature of a copulating mixed pair in Greenland. Unfortunately the outcome of this particular mating isn’t known as both birds were shot!
So, on balance a ‘mid-range’ pale Iceland Redpoll seems a plausible suggestion (unless the bird isn’t really as big as is suggested) and I might tentatively identify it as one in northern Scotland. Unfortunately you’re in the US! However, given that redpolls seem capable of turning up anywhere (eg a ssp. flammea from Michigan to Siberia) I guess it’s not impossible”

Is this a first record of ssp. islandica in North America?  I had sent this on for review because I thought it matched the subspecies well.

Near the end of February a banding crew including Mason and Taylor came to the house, and we caught a few Hoary Redpolls. At least one of them was thought to be a ssp. hornemanni (matching one of the above birds), but when measured the wing chord was near the low end for this subspecies and the high end of ssp. exilipes (75mm). There is a small overlap between the two subspecies. Mason and Taylor (2015) published a paper using these birds and others, and then proposed that the two species be lumped. There is clearly gene flow, and therefore hybridization…..and it was a reason for the proposal of lumping them…..but it didn’t pass for now at least. “The physical differences among redpolls are associated with patterns in their RNA, not necessarily their DNA” according to the 2015 paper.” In the 2015 Mason and Taylor paper, less than 1% of the genome was used and no definitive hornemanni individuals were used from Greenland. Otehr studies point to strong assortative mating between the two redpolls species in that they know how to tell each other apart, but more study is warranted.

At least 7-8 different Hoary Redpolls visited my feeders during the 3-4 week period. Additionally, there were at least 3 different Greater Common Redpolls in my yard along with a “presumed” different ssp. hornemanni bird that we did not catch (see above Photos 28-29). At the very least there were 3 good subspecies that visited the yard, with perhaps 5 different subspecies present. One can separate the vast majority of redpolls without measurements, but when possible, birds should be measured and matched to plumage characteristics, especially in cases like this, where subspecies measurements (like the Hornemann’s and exilipes Hoary redpoll) can overlap.

Here’s a ranking of the difficulty of identification for Hoary Redpolls from easiest to toughest:

1. Adult Male

2. Adult Female

3. Immature Male

4. Immature Female (overlap in traits with Common Redpoll females can be common)

When ranking traits, I often will lump them as best, secondary and tertiary in importance:

Best (you could list these three as 1a, 1b and 1c. If you have all three of these traits, you have a Hoary Redpoll). Focus on these three and take lots of photos of them. If you do this you will have very likely taken enough photos to get the other traits as well.

  1. Clean no streaked undertail coverts
  2. Clean white rump
  3. Frostier back (especially before late winter and spring)

Secondary

  1. Short stubby bill giving a steep forehead appearance….but it’s mainly only applicable to females because there’s overlap in males
  2. Wispy and/or thinning flank streaking, but immature females can be pretty streaky on flanks…….and on undertail too.

Tertiary

  1. Ochre or buffy wash to face which seems fairly common in females
  2. Pale pink in male Hoaries to reddish to Commons. A note of caution, Hoaries can gain in redness and how extensive the red is from fall to spring. Hoaries will also get browner-backed looking due to faether wear as spring approaches.
  3. Thicker bull-necked appearance (even much more so noticeable in Hornemann’s Hoary Redpoll).
  4. Widening and whitening of wing bar
  5. Smaller size of poll

The cautionary tale in all this though, is that redpoll identification can be hard. Some immature female ssp. exilipes Hoary Redpolls can be quite tricky — intermediate individuals should not just be classified as “pale Common Redpolls” because they don’t fit a “classic Hoary look”. If the photos don’t capture all the traits well, and the ID is inconclusive when considering the overlap in look between immature females of the two species, then the individual is often best left as redpoll sp.. In short though, it was a great winter where I continued my lifelong on-going passion and education for redpolls and redpoll identification. This year is looking like it’s going to be a great year for Common and Hoary Redpolls in the southern part of their range…..and with that, I wish all a winter of Happy Redpolling!

FiRN is committed to researching and protecting these birds and other threatened finch species as well. We’ve included a link to donate below, and hope you’ll help support our efforts.

I’d like to dedicate this redpoll blog to Martin Garner, who loved talking redpolls, but unfortunately passed away a few years ago at way too young of an age!

For more Redpoll Identification help see these linked resources:

http://www.jeaniron.ca/2015/redpollsRP.htm

Leave a Reply