A Closer Look: The PDX "Snow" Bunting

Bunting1_PDX121811

Fig. 1.  At first glance, this bird, photographed at Portland, Oregon, on 18 December 2011, appears to be a Snow Bunting. However, the mostly white, unstreaked lower back and rump caught our attention and further investigation of the tail and wing pattern in other photos revealed some plumage aspects that point away from this bird being a "pure" Snow Bunting. (Photo by Dave Irons)

It's not often that I look at close-up, in-focus images of a North American bird and can't identify it. And yet, there are some species (think gulls) and species pairs whose basic and immature plumages continue to challenge even the most experienced birders. Plectrophenax (Snow and McKay's) buntings fall into this category.

One such bird is currently challenging local birders here in Portland, Oregon. On 25 November 2011, Tom McNamara found a "Snow Bunting" on Broughton Beach along the south shore of the Columbia River just north of Portland International Airport (PDX). Over the ensuing several weeks it was seen somewhat sporadically along this stretch of beach.

A few days ago, the bird was observed at an alternate location adjacent to the PDX Fire Station, which is situated along the north boundary of the airport property. The bunting has proven to be far more reliable at the latter site, allowing many folks to drive right up to it, resulting in some stunning photos. The average birder in Western Oregon (west of the Cascades) does not see Snow Bunting annually although they do occur in small numbers along the northern coast (Marshall et al, 2006). We are also in range of the occasional stray McKay's Bunting, including a bird found the exact same day in coastal southern Oregon, that Jon Dunn and Dan Gibson said looked like a good McKay's (pers comm.). Dave Irons wrote a BirdFellow piece earlier about this bird that can be found here. The previous Oregon records of McKay's Bunting are 2 birds in a flock of Snow Buntings at the south jetty of the Columbia River from 23 February to 9 March 1980 (Marshall et al, 2006) and one male on 3 January 2004 at Depoe Bay (OBRC, 2010).

After failing to locate the bird during a couple of prior searches at Broughton Beach, Dave Irons and I finally saw the bunting at the PDX Fire Station on 18 December. Dave got some nice pictures of it. Upon downloading and reviewing these images, we were struggling to age and sex the bird. Some aspects of the bird were puzzling to both of us, most notably the unstreaked white rump and lower back (only minimal rusty wash) and the pattern of white in the folded wing, which seemed to show too much white for a female Snow Bunting and not enough for a male. These ambiguities caused us to consider that this bird might be a female McKay's Bunting, or, perhaps, a Snow Bunting X McKay's Bunting. Despite an extensive review of our published literature and online resources, we remained perplexed. Snow and McKay's Buntings are closely related and are presumed to occasionally hybridize where their ranges overlap (Birds of North America Online). In their basic (winter) plumages, adult female McKay's Buntings are quite similar to male Snow Buntings.

PDX%20bunting%20scaps%20DN

Fig. 2. The central scapulars -- the dark-centered feathers along the shoulder look fairly large and broad like a male. (Photo by Don Nelson, 18 December 2011)

According to the McKay's and Snow Bunting accounts in the "Identification Guide to North American Birds: Part I Columbidae to Ploceidae" (Pyle 1997), some features of this bunting more closely match Snow Bunting, particularly the wing pattern. And what sex it is? According to Rogers (2005) the shape of dark centers to the central scapulars will help determine whether it is male or female. Females of both species show relatively small black centers and always taper to a point. The shape and size of the black in male Snow Bunting is larger, broader and may not end in a point. The size and shape of the Portland bunting's central scapulars look broad and pointed, appearing to be more like a male to my eye.

One might also conclude that it is a male since the wings look rather black in most of the photos and there is a crisper lateral transition to white near the base of the primaries, whereas females should be grayer and the gray extends up farther onto the inner web. But are the feathers really black or is it an exposure issue? And in the outstretched wing shot below (Fig. 3) there is a tongue of black extending up the inner web. The longest primary covert and greater alula on a McKay's is typically mostly white with the exception of a hatch year or second year female. We were left with more questions after reviewing "Identifying McKay's Bunting" (Rogers 2005). It includes a photo of a bird photographed at Richmond, British Columbia on 20 December 2004, which is identified as a female McKay's (Fig. 6 pg 624). In terms of overall pattern, back color, and the pattern and color of the folded wings, it looks much like the Portland bird with some exceptions. Note that both the Portland bird and the British Columbia bird (Rogers 2005) were photographed during the third week of December.

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Fig. 3. Note that the transition from black to white at the base of the primaries is somewhat of an irregular pattern. Also the black extends farther up onto the outer primary (p9) similar to Snow Bunting. The extent of black on the longest primary covert and greater alula is another feature to help determine age and sex. (Photo by Don Nelson on 18 December 2011).

Other features mentioned as good for McKay's include an unstreaked white rump, yet I was able to find photos of winter Snow Buntings on the web that had white rump, including this one found in California in 2004.  Generally, the rumps of a Snow Bunting are darker than those of McKay's.

The pattern of R3 (or Rectrix #3) is apparently very important in distinguishing these two species (Fig. 4). According to Pyle (1997), R3 on McKay's is mostly white with a bit of black in the tip that is shaped like a boomerang, while in Snow Bunting R3 is largely black. It can clearly be seen below that the pattern of R3 is as described for McKay's Bunting. Yet R1 and R2 on basic male McKay's shouldn't be as black as this bird's tail according to Rogers' article.

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Fig. 4. Note that R3 is largely white with a small amount of black at the tip and extending up the shaft. (Photo by Don Nelson taken on 18 December 2011)

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Fig. 5. A slightly different view of R3. (Photo by Don Nelson on 18 December 2011).

While the pattern of R3 looks right for McKay's Bunting the amount of black in the wing and the extent of black in the scapulars looks more like a Snow Bunting.  So, what is this bird's parentage? Comments are more than welcome as the intention of writing this piece is to stimulate discussion.

I must thank Don Nelson, Lyn Topinka, Tait Anderson, Tom McNamara and Dave Irons for generously sharing their photos. This discussion would not have been possible without access to these images. 

Bibliography:

Patterson, M. and R. W. Scheuering. 2006. Snow Bunting. Pg. 569-570 in Birds of Oregon: A General Reference. D. B. Marshall, M. G. Hunter, and A. L. Contreras, Eds. Oregon State University Press, Corvallis, Oregon.

Montgomerie, Robert and Bruce Lyon. 2011. McKay's Bunting (Plectrophenax hyperboreus), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/199

Montgomerie, Robert and Bruce Lyon. 2011. Snow Bunting (Plectrophenax nivalis), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/198

Oregon Bird Records Commitee. 2010. OBRC Records Through 2010. PDF accessed online from http://www.oregonbirds.org/#.

Pyle, P. 1997. Identification Guide to North American Birds, Part 1: Columbidae to Ploceidae. Slate Creek Press, Bolinas, California.

Rogers, J. 2005. Identifying McKay's Bunting. Birding 37(6): 618-626.

Sibley, D. A. 2000. The Sibley Guide to Birds. Alfred A. Knopf, New York.

1

With Peter’s Pyle’s permission here are his comments. “Looks like a first-cycle male if this helps in the calculations, which might favor the hybrid/introgression idea (as opposed to adult male). Hope this helps.
Peter”

2

On Nov 19,2004, a hybrid McKay’s x Snow Bunting was found and subsequently photographed in Harrison Hot Springs, BC. The pictures were reviewed by two Ornithologists at the University of Alaska’s Museum of the North, and credited as a valid hybrid. I contacted both and asked them to review the images I made to get their opinion of Hybrid or which Bunting. So far, I have heard back from Dan Gibson in an email “A little more tail-white than it absolutely needs, but your bird looks like a bona fide Plectrophenax nivalis to me.”.Lets see what the other experts weigh in with….

3

Like many Oregon birders I have very little experience with Snow Bunting and none with McKay’s.

What I can say is this bird appears to be in extremely fresh plumage. Those wispy white tips to the back (and rump?) will soon wear away, I suspect, revealing a very black back.

If this bird remains into February, perhaps we’ll see some plumage change that will be revealing.

Greg

4

Shawneen’s research and efforts to synthesize the various field marks that separate Snow and McKay’s Bunting are most appreciated and in many ways enlightening.

I come away from this discussion with more questions than answers, as it seems the ID criteria being used to differentiate these species are a bit of a moving target. Some sources suggest that the amount of white and lack of streaking on the rump is useful, but, as Shawneen points out, it’s not too hard to find images of “Snow Buntings” with mostly white and unstreaked rumps. Pyle (1997) leans heavily on the pattern of white and black in R3 (thoroughly discussed in this article) and yet when experts familiar with both species look at images of the Portland bird being discussed in this article, which displays an R3 pattern that matches Pyle’s depiction for McKays, they still feel the sum of the parts fits Snow Bunting.

I find it hard to disagree with those who think this bird is a Snow Bunting as the general/overall appearance of this bird strikes me as being too dark above for McKay’s. This discussion also causes me to wonder about the identity of the putative female McKay’s Bunting from Richmond B.C. (photo appears in Rogers 2004). I would like to better understand why this bird was/is being called a female McKay’s, as it strikes me as looking nearly identical to the current Portland bird. The photo in the article does not clearly show the scapular pattern used to sex that bird. If such photos exist, why were they not included in the article?

The real point of offering articles like the one Shawneen Finnegan prepared is to stimulate meaningful discussion around topics like this one, where agreement among various authoritative reference materials is lacking.

5

Both Greg (here) and Alan (in the linked article on the Coos Co. bird) make good points that I was going to make myself, each of which would help tip the debate toward Snow Bunting. Re: Don’s comment, I was a co-discoverer of that Harrison Hot Springs, BC, bird in 2004, and I wouldn’t say that the Alaska commentators came to any firm conclusion that it was a hybrid. I’m not able to dredge up the old correspondence now, but what I recall Dan Gibson and others saying was that the bird was consistent with a hybrid or possibly even a pure McKay’s but that nothing conclusive could be told from the photos taken by Dennis Paulson and myself because we were unable to photograph (or even get a good look at in the field, errrg!) the key feather-by-feather patterns on tail and wings. However, that bird was paler overall in coloration than the current PDX bird.

I have posted a series of photos here:
https://picasaweb.google.com/114481402865976904547/BCBuntings?authkey=Gv1sRgCMeUmqHXqIWS4QE
This photo set documents the 2004 Harrison Hot Springs BC bird, along with its Snow Bunting companion for a nice side-by-side comparison. It also includes a few shots of the roughly contemporaneous Iona, BC, birds (a male McKay’s and possible female McKay’s) from another photographer. Further, it includes photos of museum specimens, plus a few other shots for context & reference. This photo set was one I had put together at the time and shown at Portland Birders Night.

The upshot is that the Harrison BC bird probably cannot safely be ID’d to species because the relevant tail and wing feathers were not photographed. However, I think it’s potentially helpful to view these old shots anew, for context with the 2011 Oregon birds. I did not follow the discussion of the recent SW Oregon bird, but if all we have to go on is the photograph at the other Birdfellow article linked here, I don’t see how it provides enough evidence to safely support ID as McKay’s. And along with Dave, I fail to see why the Richmond BC bird in the Birding article is a McKay’s. Re: the PDX bird, Shawneen’s analysis here is excellent, and I’d love to see the analysis continue after consideration of further photos (some of which have been outstanding) and outside expert comment.

I took some video of the PDX bird yesterday, and it is posted here:
https://picasaweb.google.com/114481402865976904547/PDXBuntingVideos?authkey=Gv1sRgCITt57jLspT7Fw
Alas, it does not show the diagnostic tail or wing features, but it does clearly show that at least one of the central retrices is black well toward its base. In minutes 1:35-2:07 of the first video, and in good portions of the second and third video, you can see a region of jet-black retrix showing through a patch of parted or missing white uppertail coverts. Steve Berliner had also noted this the previous day, and this is shown slightly in one of his photos as well: http://www.pbase.com/sberliner/image/140457301
Black-based retrices would argue for Snow Bunting.

I think that close analysis of a bird like this is an excellent application for Birdfellow’s format and resources. If Shawneen and Dave are willing, I’d recommend a revised and comprehensive analysis in a further article once the dust has settled. You’d be free to fold in some of the BC shots from Dennis and myself if you’d like.

6

And here’s the link on the “Hybrid McKay’s x Snow Bunting, 2004”
http://www.pugetsound.edu/academics/academic-resources/slater-museum/biodiversity-resources/birds/images/land-birds/
and images
http://www.pugetsound.edu/files/resources/4410_snowbunting.jpg

And yet another “Hybrid” image (though all-white&Black unlike the PDX bird)
http://www.birdphotography.com/species/mcbu.html

7

Thanks, Jay, for folding in this information and photos, particularly the museum shots. I would be more than happy to compile it as the best I can at a later time. I miss having access to a good museum nearby. There is nothing like looking at trays of specimens to help in situations like this.

The best part about looking at birds in more detail like this is the learning involved, both at what is known and what is not. Without this bird’s appearance and people’s great pictures, we wouldn’t be wondering how much white in the tail a Snow Bunting can have and still be considered a “pure” Snow Bunting.

And thank you, Dave Lauten, for adding the photos of the “McKay’s” Bunting pics from Seven Devils Wayside onto BirdFellow from a month ago.

8

Interesting bird. If I had not seen the spread tail, I would have said male Snow Bunting, case closed.

But we have a bird with extensive white on R3, which would have me initially thinking that either the bird has some McKay’s Bunting in it or variation in Snow Bunting is more extensive than we thought.

Regarding Snow x McKay’s hybrids, while it has now been shown that there is gene flow between McKay’s and Snow (one way – McKay’s to Snow), genetically intermediate birds can be phenotypically like one species or the other. And in the cases of a couple of genetically intermediate females tested, one was largely McKay’s but looked like Snow and the other was largely Snow but looked like McKay’s! Thus attempting to identify Plectrophenax hybrids in the field or from photos may just be an exercise in futility especially when there are questions about intraspecific variation.

9

One expert told me in a private conversation that he felt Snow and McKay’s Buntings may not be good species. Jason Rogers shared the following “A study by James Maley and Kevin Winker on Plectrophenax juvenile plumages supports recognition of two species. McKay’s Bunting is able to retain its morphological and genetic integrity on its breeding islands, probably because of its arrival time and its very high density there.”

10

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