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I can just imagine the responses of some upon first glancing at September's photo quiz: "What the ....?!" Yeah, what the heck are those? One can flip back and forth through The Sibley Guide for eternity and not find anything resembling these birds. And, of course, they have to be of the same species for this quiz, so at least we essentially have two views to use. Are these leucistic (loo-SIS-tic) somethings-or-other? Even if they were, the yellow bills and gray heads and backs still don't match much in our field guides. Well, if they're not aberrant birds, then let's use what is the most obvious feature of the beasts, the extensive white coloration.
Our quiz birds are apparently fairly small (relative to the short vegetation surrounding them) and that suggests that they are passerines. There just aren't that many passerines with such large amounts of white in wing and tail, that these must be Plectrophenax buntings, either Snow or McKay's. Unless they're leucistic things. But, let's see if we can match the wing and tail patterns to something and if we cannot find anything suitable, then we'll consider oddballs. (Interestingly, I have seen no small number of pictures of birds that were purported to be of Snow Buntings -- or, even, of McKay's Buntings -- well outside of normal range that were actually leucistic individuals of fairly common species, such as House Finch and House Sparrow, so leucism is definitely something to consider when looking at a small passerine with so much white.)
If these are, indeed, Plectrophenax buntings, the extensive gray on the upperparts must indicate that they're juveniles, because immatures and adults certainly don't sport such coloration. Some quiz-takers may have googled for pictures of these species, hoping that someone has such of juveniles on the web and such are present and they look at least something like our quiz birds. That was probably comforting. But, how can we separate the two species in juvenal plumage, when the field guides either don't illustrate juveniles of either or do so only of Snow Bunting? And, no wonder juvenile McKay's Buntings are not illustrated, with virtually the entire world's supply of the species being restricted as breeders to two difficult-to-access islands in the Bering Strait, there really aren't that many humans that get to see the plumage. That is because they molt out of it before migrating. Of course, that doesn't help us solve the quiz.
But, this is where knowledge of molt strategies can help us out! I have proselytized for years about birders becoming familiar with molt patterns as they can provide strong clues in bird ID in many situations... such as this one. This will help us here, as many juvenile passerines (particularly longer-distance migrants and the more derived group that is the nine-primaried passerines) retain their juvenal wing feathers through their first year even when they replace their juvenal body plumage in their pre-formative molt. Thus, when they leave the nest, they are already wearing the wings that they'll sport for the next year or so. That means that we can use features of the wings of immatures (first-winters) to enable our identification of these birds.
The primary difference between the two species of Plectrophenax in wing pattern is the amount and placement of white and this is true, too, of the tail. So, cracking open our well-thumbed copy of Pyle (1997), we read that McKay's Bunting (pg. 605) can be told from Snow Bunting by "... outer pp [primaries] with white or whitish extending beyond the tips of the pp covs [coverts] (Fig. 314)...." Knowing that the bit of black on the leading edge of the wing of the right bird is on the longest primary covert, we can see that there is extensive white on the leading edge of the wing distally. Quickly looking at the tail, we cannot easily determine the exact pattern, but it is also extensively white; Snow Bunting has a mostly dark tail, particularly in the first plumage cycle. I took this picture of two juvenile McKay's Buntings at St. Matthew Island in the Bering Strait, AK, on 22 July 2004. And, boy, you should see the adult males! Stunning!
Pyle, P. 1997. Identification Guide to North American Birds, part I. Slate Creek Press, Bolinas, CA. 732 pp.
The following people (listed by submission date beginning with the earliest) submitted correct answers for the September Bird Photo Quiz—McKay's Bunting:
The following list shows the number of submissions for each species guessed.
The photo and answer for this quiz were supplied by Tony Leukering.