Late-Winter Early-Spring White-winger Rush

Winter gull season is supposed to wind down by mid-March here in Northern Illinois, but we've been fortunate enough to experience a late wave of new birds in Lake County. I spent three consecutive days working the area around the Countryside Landfill last week (25-27 March 2015). Below is a summary of my totals (all adults unless otherwise stated), followed by photo highlights.

Wednesday, 25 March 2015:

• Thayer's Gull (12 - 1st cycle, two 3rd cycles)
• Kumlien's Gull (2)
• Glaucous Gull (2 - 1st cycle, 3rd cycle)
• Great Black-backed Gull (1 - 1st cycle)
• Lesser Black-backed Gull (3)

Great Black-backed Gull (1st cycle)



Glaucous Gull (1st cycle)



Thayer's Gull (1st cycle)



Thayer's Gull (adult)



Thayer's Gull (adult)



Thayer's Gull (adult)



Lesser Black-backed Gull (adult)



Thayer's Gull (adult)



Thayer's Gull (3rd cycle type - photo 1 of 2)



Thayer's Gull (3rd cycle type - photo 2 of 2)

Thursday, 26 March 2015:

• Thayer's Gull (10 - 3rd cycle)
• Kumlien's Gull (2)
• Glaucous Gull (1 - same 1st cycle)
• Great Black-backed Gull (1 - same 1st cycle)
• Lesser Black-backed Gull (2)
• Cook-Inlet Gull (putative Herring x Glaucous-winged adult)

Kumlien's Gull (adult - photo 1 of 3)



Kumlien's Gull (adult - photo 2 of 3)



Kumlien's Gull (adult - photo 3 of 3)



Lesser Black-backed Gull (adult)



Thayer's Gull (adult)



Herring and Thayer's Gulls (adults)



Kumlien's Gull (adult - photo 1 of 2).



Kumlien's Gull (adult - photo 1 of 2).



Thayer's Gull (adult)



Thayer's Gull (adult)



Putative Cook-Inlet Gull (adult - photo 1 of 3).



Putative Cook-Inlet Gull (adult - photo 2 of 3).



Putative Cook-Inlet Gull (adult - photo 3 of 3).

Friday, 27 March 2015:

• Thayer's Gull (12 - 3rd cycle type)
• Kumlien's Gull (4)
• Great Black-backed Gull (1 - same 1st cycle)
• Lesser Black-backed Gull (3)
• Thayer's/Kumlien's intermediate type (2 adults)

Kumlien's Gull (adult - photo 1 of 2).



Kumlien's Gull (adult - photo 2 of 2).



Thayer's Gull (adult)



Thayer's Gull (adult)



Kumlien's Gull (adult - photo 1 of 2).



Kumlien's Gull (adult - photo 1 of 2).



Thayer's Gull (adult)



Thayer's Gull (3rd cycle type - photo 1 of 2).



Thayer's Gull (3rd cycle type - photo 2 of 2).



Kumlien's and Herring Gulls (adult, 3rd cycle type).



Same two individuals above.



LBBG and Herring Gulls (adult).

More Photos of Lake Michigan's Putative Chandeleur Gull

I had completely taken the presumed Chandeleur Gull (Herring x Kelp hybrid) that spends its winters between Berrien County, Michigan and LaPorte County, Indiana, off my radar for the season. Having last seen it on Thanksgiving Day 2014, I was very happy to happen upon it on Sunday while gull-watching from the pier at the harbor mouth in Michigan City.

Putative Herring x Kelp ("Chandeleur Gull"). Michigan City, IN. 22 March 2015.

The bulbous-tipped bill is seen well here as is the thickness to the whiter trailing edge on the outer secondaries.

Back in late November, it was still molting its outer primaries and secondaries:

Michigan City, IN. 27 November 2014.

Note that the outer greater primary coverts still show black streaks, despite this bird showing an otherwise definitive adult plumage (as was the case in October 2013). I think it's safe to say that the small white mirror on p10 is a direct influence from its Kelp ancestry, as is the extensive black on both webs of p8-p10.

I can't think of any other instance that I've observed an adult gull with black subterminal marks all the way down to the first primary.

Note the apparent thickness of the trailing edge to the secondaries, and much more interesting, the wide white tips to the inner primaries. It is known that adult Slaty-backeds show these deep white tips to the inner primaries (deeper than what is seen here), but an extensive photo study online has taught me an excellent lesson: adult Kelp Gulls can show very broad trailing edges as well as thick white tips to the inner primaries (see here for an extreme example). This is a bit different on presumed hybrids with Great Black-backed influence.

Yellow-green leg color with grayish tones points away from two pink-legged parents (i.e., Herring x GBBG).
Flesh-colored feet is something I've regularly noted on yellow-legged adults (such as Yellow-footed Gull, Lesser Black-backed and Ring-billeds).

Shows a somewhat broad secondary skirt and relatively long legs. 

I will reiterate my conviction that Chandeleur Gulls are a "legitimate" hybrid form. I don't find it difficult to believe that Kelp Gulls, which are generally expanding north, and Herring Gulls, which are generally expanding south, have converged again in small numbers somewhere in the Gulf Coast/Caribbean. You can read more of my thoughts on this here.

Thoughts on Pink Ring-billeds

They're back...

Ring-billed Gull (adult). Cook County, IL. 21 March 2015.

Pink adult Ring-billeds have returned to northern Illinois. The two working-theories are, 1) This pink hue is diet-related and that these birds may have spent their winters south of us (Gulf Coast region?) stocking up on astaxanthin, or 2) This pink hue is an external colorant caused by exposure to the large ore piles where these birds nest.

Interestingly, in my 6 years of careful observation of these individuals, it seems much more likely that pink birds pair up with pink birds - at least this is what is apparent while some 400 adults courting and establish bonds near my home in northern Illinois. Of these 400 adults, approximately 5% show some amount of pink in their plumage. Could it be that pink birds attract pink birds, or could it be that they're now staking out nesting sites on the ore piles in East Chicago? Hence, birds that are paired up may be exposed to the slag simultaneously, while birds not nesting on the ore piles remain white and tidy.

The latter theory may be supported by the fact that these "pink" individuals become more pink in April and May, suggesting their roosting/nesting sites continue to leave them with ongoing exposure to the ore piles/dust. Although one has to wonder why their legs and bills aren't tinged with pink if this coloration is due to ore piles! Do they do that well of a job of bathing their bare parts?

I was told by birders in California, Montana, and Pennsylvania that they're now seeing pink RBGUs too. Strangely, Cleveland lakefront birders don't see Ring-billeds that look like this. Lots of questions and I've never been more unsure about this phenomenon as I am this year.

Please send me any photos or comments on these pink Ring-billeds should you have any! Thanks.

Adult Lesser Black-backed with White Tip to P10

Winter gull season is winding down here on southern Lake Michigan, evidence by the large exodus of American Herrings which have mostly been replaced with Ring-billed Gulls. Adult Herrings that do breed in the area have already picked out their nesting spots. For instance, the very small colony that breeds on the industrial building at Waukegan Harbor was already collecting nesting materials on Saturday.

Overall, the weekend was pretty uneventful, but I did manage an adult Thayer's and adult Lesser Black-backed.

Thayer's Gull (adult). Waukegan, Illinois. 14 Mar 2015.

Thayer's Gull (adult). Waukegan, Illinois. 14 Mar 2015.

The adult LBBG was definitely the highlight on Saturday, showing an all-white tip to P10, a mirror on P9 and a partial subterminal band on P5:

LBBG (adult). Libertyville, IL. 14 Mar 2015.

From the hundreds of adult LBBGs that I've seen, I've only observed an all-white tip to P10 twice before this. European gull aficionado, Mars Muusse informed me of just how rare this pattern is, with only 6 out of 931 (~ 0.6%) showing this in their sample of adult males and females combined.

Miscellaneous Herring Photos:

Photo 1 of 2.

Photo 2 of 2.

Photo 1 of 2.

Photo 2 of 2.