26 December 2012

Hammond Kumlien's Returns

Since at least 2009, this adult Kumlien's Iceland Gull has returned to the same marina to spend its winters. Most interesting is that it holds a strict winter territory similar to a raptor. It perches atop a "No Wake" sign at the harbor mouth and does not associate with the other gulls. In fact, any gull that enters the harbor mouth is swiftly chased off by this northern beauty:

Adult Kumlien's Iceland Gull. Hammond, IN. 24 December 2012.

17 December 2012

A Nomenclature Correction on Ageing Near-adult Birds

It's been brought to my attention that the usage of the term "4th cycle" may be a bit misleading. I often use 4th cycle for birds that are very close to being adults, but may show a few signs of immaturity. For instance, this American Herring looks mostly adult, less its pink bill with black subterminal markings that are a bit more defined than a winter adult. Also note the sparse black marks on the tail:

Milwaukee, WI. 02 December 2012.
Another example of what I would call a 4th cycle is this Thayer's with just a few specks on the uppertail and the black subterminal marks on the bill:
Lake County, IL. 16 December 2012.
Although these individuals may very well be in their 4th plumage cycle, there is no definite way to prove that without more evidence from banded individuals. How can I be sure this isnt' a very advanced 3rd cycle, or even a somewhat retarded 5th cycle? So, from this day forward, I've chosen to abandon the usage of "4th cycle" without inserting a disclaimer such as "possible 4th cycle". Alvaro Jaramillo first brought this to my attention and argued the term "near adult" is much more informative and less assuming - I agree!

I do feel, however, that we should continue ageing 1st, 2nd and 3rd cycle birds as such since we know so much more about what each generation of those feathers should look like, for the most part. I am tentatively choosing to label birds with marked tails, tertials and sub-adult like bills "3rd cycles". I will be happy to adjust the usage of this term if anyone can provide me with a 4th cycle+ example of a bird showing these features. Although there may be some guess-work involved here as well, it's a convenient system that we as field observers must have in order to communicate.

11 December 2012

More Intermediate Thayer's/Kumlien's and a 2nd Cycle Thayer's

Greg Neise and I teamed up for some Lake County gulling on Saturday. We hit the LC Fairgrounds first where we were treated to this:

Adult Kumlien's. Lake County, IL. 08 December 2012.
We went back and forth about the possibility of it being an intermediate Thayer's/Kumlien's, and although it may be, I leaned towards Kumlien's because of the limited markings on the primary tips, but especially because of the unmarked P5 - this has not been documented in the leading identification papers on Thayer's Gull:

Note the large, all white, tip to P10 and unmarked P6. This individual exhibits a pattern similar to PLATE I in Howell and Dunn, but the shade of darkness is much more extensive.
We then headed for North Point Marina, running into some nasty snow/rain mixture along the way, but just as we were approaching our destination, the rain stopped and it cleared up with partial sunshine!

We found 2-3 Kumlien's types and 2-3 Thayer's - no Glaucous or LBBGs,  which was somewhat of a surprise.

2nd cycle Thayer's Gull. Lake County, IL. 08 December 2012.

Although P10 is with a large white tip, P6 is with a full subterminal band. This individual resembles PLATE P in Howell and Dunn. I thought it was best to keep this one in the "intermediate" category, but to my eyes, the under pattern suggests Thayer's.
We also had this beast of a 2nd cycle Herring with an almost completely unmarked bill:
The adult-like bill pattern is just another example of the infinite variation found at the species level with Herring!

03 December 2012

Pinkish Bills in Adult-like American Herrings

Here's an adult-type American Herring with a mostly pink bill:

Milwaukee, WI. 02 December 2012.
The visible primaries have a perfectly looking adult aspect and the upperparts appear solidly gray, but the bill pattern suggests a sign of immaturity.

Here's what the open wings and uppertail look like:

Note the dirty alula and marked rectrices. This individual is not a definitive adult, but rather, a 4th cycle bird.

Also of interest are the bold black outlines to the shafts of the the primaries and greater primary coverts. Is this another sign of immaturity?

01 December 2012

Apparent Tone in Blackish Wingtips and Angle of Observation

It's no secret that a single photo of a gull at one point in time can be very misleading. This post is just another example of that. Specifically, note how the apparent shade of this bird's wingtips go from "sooty black" to nearly "jet black" depending on its angle to the observer:

Adult Thayer's/Kumlien's type. Lake County, IL. 21 November 2012.
This seems like a common problem with Thayer's/Kumlien's types and Glaucous-winged hybrids such as this individual:

Adult Glaucous-winged hybrid (GWGU x WEGU or GWGU x HERG). Gray's Harbor, WA. January, 2012.
Note the "apparent" change in lighting. This is due to a slight change in angle (by both the observer and the bird). In the top photo, I observed the bird on my right, slightly from the front. In the bottom photo, the bird is now slightly to my left, viewed from behind. There was no change in environmental conditions or camera settings in these two photographs.The overall effect on the wingtips is dramatic and likewise on the gray upperparts.  
Ultimately, I think it's safest to make an assessment of wingtip coloration in profile; preferably using a known species for side-by-side comparison.