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Thursday, December 15, 2011

A little out-of-county jaunt

But this was no ordinary chase. This was a bird (Slaty-backed Gull) we've been thinking about for many years now, but haven't even had a candidate to chase after anywhere in Michigan. The only existing Michigan record is from 1981, a one day wonder at the Sault Ste. Marie dump which was not chasable. This bird has provided little solace. Especially in light of the rash of recent records in the Great Lakes region, notably multiple records from Minnesota and Wisconsin, and at least one from the Illinois/Indiana area of Lake Michigan. Anyway, not a few of us state listers have dreamt of finding our own adult Slaty-backed Gull at our local dump. It just seems SO identifiable, and just a matter of time. But in this case, Dan Duso of the Saginaw Bay area found himself in this enviable position while birding the Republic Landfill near Standish, Bay County, 2 days ago. His initial reports and photos of a possible Slaty-backed Gull started to trickle out on the 13th, and the first chasers arrived on scene yesterday, posting these tantalizing photos which appeared to clinch the ID issue (with a mantle this dark one really only had to assess the extent and position of white in the outer primaries to make a confident ID).

So, the chase was on. I arrived mid-morning and was able to get some pretty amazing views as this bird hurtled over the dump with 1000+ Herrings, ~10 Glaucous, 1 Great Black-backed, at least 2 Iceland Gulls, and a handful of Ring-billeds:This was a long-awaited life bird for me, and will represent a 2nd state record if accepted by MBRC. I won't go to the mat on ID other than to say that every assessable field mark I checked appeared to be pretty classic for Slaty-backed Gull. In terms of age, it may not be quite fully adult, as evidenced by the dusky bill and obvious brownish cast to the primary coverts and primary bases. The tail of this bird conclusively shows no black (we had thought from Dan Duso's initial photos that it did have some black). So it could plausibly be either only a 4Y bird which has not quite reached full definitive plumage (like some Great Black-backeds often do), or a full adult (=after third year [ATY]). Pyle Guide II mentions that 4Y (of which less than 5% are assignable confidently to this category) is best identified by "outer primary coverts with more extensive blackish markings" (vs. slate gray or with "limited blackish on outer webs" in A4Y), and small p10 mirrow with no p9 mirror (vs. either just p10 or both p9 and p10 with "distinct white mirrors".) I don't think we have enough to confidently call this a 4Y, but would like to hear others' opinions. Here is today's eBird checklist:

Kudos to Dan Duso for finding this amazing record, Myles Willard and others for checking up on it, and getting the word out, and to Karl Overman for being sure we all knew about it.

Monday, December 5, 2011

The joy of long-distance Thayer's Gull identfication

One of my easiest remaining Kent Co. ticks is Thayer's Gull. Problem is, the only location in our lovely county which has a gull concentration is the Kent Co. landfill. And the viewing at this location is about as inopportune as it gets for gull watchers. The closest vantage is about .35 miles from the dump site, or 567 m (~5.67 football fields):Thayer's Gull identification is a quagmire in and of itself, so trying to do it at this distance is doubly troublesome. Some basic background: Thayer's and Iceland Gulls clearly constitute a clade, but instead of fitting nicely into 2 bimodal categories which we can easily separate (as suggested by the names), they form a cline of variation from black-primaried birds (=Thayer's) in their western arctic breeding areas to white-primaried birds in the European arctic (=nominate Iceland [glaucoides]). The 'in between' birds in the eastern N. American arctic, are grayish-primaried and are called "Kumlien's" Iceland Gull. The challenge with this group is deciding which phenotypes to classify as pure Thayer's, which as pure Kumlien's Iceland, and which to classify as unknown. Some of the birds between Thayer's and Kumlien's Iceland are even referred to as hybrids/intergrades, though on what basis (and what such a moniker actually connotes: if the bird looked exactly like both its parents how is that a hybrid/intergrade?!?) I don't claim to know. So to get to my bird from today let's start here: a plate comparing the wingtip pattern of large adult gulls, from "Gulls of North America, Europe, and Asia" by Olsen and Larsson (2003). Birds 13-16 are given to show the range of variation of acceptable Thayer's from darkest above to palest below, while bird 17 defies identification (would genetics show this bird to classify easily as one or the other when there's a cline of variation? I personally doubt it, but am not a geneticist so someone please relieve me of my ignorance), and plate 18 shows the extreme dark example of Kumlien's Iceland:
Long story short: I observed 2 adult kumlieni/thayeri today that were close to bird 17, but never could get an extended study of either bird, nor photos. But I did attempt to get video. I thought I had failed to capture my target, but in going through the video clip , I was shocked to see that the bird actually did unwittingly enter my screen, totally unbeknownst to me at the time (watch the upper left corner between 1:32 and 1:46). This bird, seen well, was darker gray above than Herrings, with dark eye and bright pink legs, as well as diffuse neck and head streaking. But n order to study the wingtip pattern of this bird I have created the following screencaps from the original clip, which are higher resolution that what you'll get on the youtube video (analysis to follow):

First off, the bird clearly applies to either bird 16 or bird 17 in Olsen and Larsson. How to decipher which? Well, the book doesn't really say in concrete terms. The caption to bird 16 reads: "Outer wing appears streaked blackish. Note black extension on outer webs of p9-p10, emphasizing white mirrors. Shows blackish markings as far as p5. Upperwing darker gray than in kumlieni." The caption for bird 17 says: "This example could represent minimal dark streaking in thayeri, with no dark markings on p5, or maximal dark streaking in kumlieni." How's that for hedging! Let's analyze this bird's outer primaries in more detail. I went into Photoshop and labelled each primary tip from the 2 best screencaps: It does appear that my bird lacks any markings on p5 (assuming I've labelled the feathers correctly), and that it lacks the black terminal markings on p10 shown on bird 16. The outer web of p9 pretty clearly lacks black in the area of the mirror, but so do both birds 16 and 17. The only other field mark I can garner from the plate would be the color of the pigmentation on these feathers: blacker on bird16 and slate gray on bird 17. I am not sure the answer to this one (nor the value it has as a definitive field mark!).

So, in the end, as so often happens, I think this is a bird we need to let go, as much as I would like to have a Thayer's Gull for Kent County. I left this and the other adult like it as Thayer's/Iceland Gulls on my eBird checklist. Birds like this may or may not "qualify," even with genetic data, as either species. But even if it did, we'd be hard-pressed to do so when its phenotype is so close to bird 17. Or perhaps we humans would do better to classify all birds in this clade as Thayland Gulls or Iceyeri Gulls? Alternative opinions here are welcome, of course (comment box below).

Fortunately for me, with upwards of 1,200 gulls present of late, as well as the influx of Thayer's in the western Great Lakes: I think the chances for finding a bird more like birds 13-15 (or heck, even a 1st or 2nd cycle bird) will be pretty good in the coming weeks. Let's hope that any such bird poses as well as this one did!

Saturday, December 3, 2011

Black Scoters!

Left the house around 10:30AM to begin checking local lakes for Black Scoter (one of my most wanted Kent Co. ticks in the waterfowl category). But since I live in Montcalm, I've made a habit of checking my local Montcalm large lake: Whitefish Lake daily, and this morning was no exception. First duck I saw was a White-winged Scoter (after an absence of 2 days since seeing 1 and possibly 2 of these 3 days ago (see I quickly realized there weren't a lot of ducks present due to the duck hunters chasing them around. But a scan to the south revealed a single, white-cheeked duck, in with 3 Common Goldeneyes, which was larger than them. Body size ruled out the last contender: Ruddy Duck, and sure enough, I had found my target bird within 10 minutes of leaving the house. Here is the checklist, with photos of both scoters: . For those looking to chase here is the map with access points and approximate locations of the scoters as of 11AM.All of this made me believe I had a good shot of finding Black Scoter in Kent as well: there must have been an influx last night as these birds were not present the past 2 days and the dreary, rainy weather is good at 'knocking down' migrants. But I planned on having to reach Kent Co.'s larger lakes, such as Lincoln Lake and Wabasis Lake in order to maximize my chances for this rare sea duck. But astonishingly, only 1.5 miles away I found ANOTHER Black Scoter on a much smaller lake: Sand Lake. Sand Lake is bisected by the Kent/Montcalm Co. line, and almost all of the time the Aythya flock (primarily Ring-necked Ducks) are on the north shore of the lake, well within Montcalm. At first this is indeed where the scoter was, but it quickly flew south, and swum to within 50-60 feet of the Kent shore! Even the Ring-necked Ducks rarely if ever do this, so my luck was out of control today. (side note: had this not happened I was prepared to grab my kayak and attempt to push the bird into Kent, fortunately I didn't have to do this). This map shows the location of the county line, as well as where I saw the Black Scoter. I took this video clip to show conclusively that the bird was in Kent Co., from the locations labelled on the map (note the peninsula which will be visible in the background of the video clip):Here is the Kent Co. checklist with photo:
and a better video clip for ID purposes:

What a day! Heading back out to check Lincoln Lake as we speak, who knows what I'll find on a day like this.