Monthly Notables January 2016

• Ivory Gull (1st cycle). St. Louis County, Minnesota. 01 January 2016.
• 12th State Record. Took a 6 day absence, only to return to Canal Park on 15 January 2016. It was last seen on 24 January appearing weak and on the brink of expiring.
• Mew Gull (1st cycle). Caddo County, Louisiana. 01 January 2016.
• 1st State Record.
• Ivory Gull (1st cycle). Douglas County, Wisconsin. 05 January 2016.
• Just a few miles from the Duluth bird, this individual was found dead. A partial specimen was given to the Field Museum in Chicago.
• Slaty-backed Gull (adult). Pierce County, Washington. 06 January 2016.
• Reoccurring/Continuing. 
• Slaty-backed Gull (adult type). Jefferson County, Wisconsin. 07 January 2016.
• Slaty-backed Gull (3rd cycle type). Walla Walla County, Washington. 08 January 2016.
• First for eastern Washington.
• Kelp Gull (adult). Summit County, Ohio. 10 January 2016.
• Resighted after a ten day absence.
• Thayer's Gull (adult). Horry County, South Carolina. 11 January 2016.
• 1st State Record. Adult showing a single mirror on p10 and none on p9.
• Black-tailed Gull (3rd cycle type). Clinton County, Illinois. 11 January 2016.
• 2nd State Record.
• Mew Gull (sub-adult/3rd cycle type). Lorain County, Ohio. 12 January 2016.
• Ivory Gull (1st cycle). St. Louis County, Minnesota. 12 January 2016.
• Another addition to the Ivory Gull saga in St. Louis County this month. A 1st cycle was found in a backyard in Ely, MN, being mobbed by crows. It was picked up and looked after by rehabbers and then released shortly after. All this while the Canal Park bird was missing in action. No photos were taken of the Ely bird (some 100 miles north of Duluth) and so whether this is a 3rd Ivory Gull or not is unknown. Three days later the Canal Park bird did reappear. 
• Iceland Gull (1st cycle). San Diego County, California. 18 January 2016.
• Mew Gull (1st cycle). Knox County, Maine. 18 January 2016.
• Vega Herring Gull (adult). Cameron County, Texas. 18 January 2016.
• 6th (7th?) State Record.
• Slaty-backed Gull (adult). Contra Costa County, California. 19 January 2016.
• Franklin's Gull (1st cycle). Volusia County, Florida. 19 January 2016.
• California Gull (1st cycle). Kings County, New York. 19 January 2016
• Vega Herring Gull (1st cycle). San Mateo County, California. 20 January 2016.
• Iceland Gull (1st cycle). Brevard County, Florida. 21 January 2016. 
• Common Gull (adult). Dartmouth, Nova Scotia. 25 January 2016.
• Slaty-backed Gull (adult). Solano County, California. 25 January 2016.
• Thayer's Gull (2nd cycle). Northampton County, Pennsylvania. 26 January 2016.
• Black-headed Gull (adult). Vancouver, British Columbia. 26 January 2016.
• Slaty-backed Gull (adult). Will County, Illinois. 26-29 January 2016.
• This same individual was found some 70 miles to the northeast at Montrose Harbor in Chicago on 30 January 2016. It was observed for about an hour before it flew off to the north, not to be seen again. This is now the 20th gull species seen at this site.
• Thayer's Gull (adult). Cecil County, Maryland. 27 January 2016.
• Slaty-backed Gull (adult). Milwaukee County, Wisconsin. 30 January 2016.
• Photo comparisons suggest this is a different adult than the one observed earlier in the month in Johnson Creek, WI and the individual observed in Illinois.
• Sabine's Gull (1st cycle). St. Vincent's, Newfoundland. 31 January 2016.
• A rare sighting from land. Exceptionally rare in North America in winter.

January 2016 Quiz

Intermediate Thayer's/Kumlien's Gull. Whiting, Indiana. January 2015.

We begin 2016 with classic, large white-headed gull, muddiness. This adult type white-winger evoked some interesting discussions this month. Here were the answers I received from you guys:

• 22 Thayer's Gull
• 14 Kumlien's Iceland Gull
• 3 Herring Gull
• 2 Thayer's/Kumlien's Gull
• 1 Glaucous-winged x Herring

We can rule out Herring Gull - not because of the extensive white on the outer primaries - but by the paleness of the pigment on the outer primaries. Note that some Herring Gulls, particularly in Eastern North America, show reduced black and thayeri wingtips like the individual below. The pigment is a true black:

Florida; January.

Back to our quiz bird. In the field, we'd want to gauge its size by comparing it to other species if possible:

Herring Gulls with Quiz bird (right)

This wasn't a very large gull, averaging smaller than most of the surrounding Herrings. For this reason I've dismissed a Glaucous-winged x Herring Gull hybrid (which can show a similar wingtip). 

It's clear from the photo above that the wingtip is significantly paler than the black shown on the adjacent Herrings. This is outside of my comfort zone for a "pure" Thayer's type. For some people, this would be a perfectly acceptable Kumlien's Iceland Gull, and it very well may be. However, my reason for identifying it as a Thayer's/Kumlien's intermediate type is the extent of black on p5. 

It's currently accepted that the majority of Kumlien's (in core Kumlien's winter range) don't show a complete subterminal band on p5 as is seen here. Further, the amount of pigment bleeding onto the inner webs of p9 and p10 is more reminiscent of what we see in Thayer's Gull. If the wingtip was a shade darker - a more genuine black - I would've readily identified our quiz bird as a Thayer's Gull.

A couple of comments in the answers provided mentioned eye color as a reason why this would be a Kumlien's Gull. It should be known that iris color in both Thayer's and Kumlien's is highly variable - some Kumlien's have dark eyes while some Thayer's have pale eyes. In short, eye color is not a helpful field mark in trying to distinguish these two taxa.

It's not uncommon to find wingtips like this here in the Lake Michigan region and elsewhere in the Great Lakes. These birds are controversial at best, and some gull enthusiasts have recently begun calling them "Lake Michigan Gulls" as they appear to be the center of the divide. Our safest bet is to think of Thayer's/Kumlien's as a continuum rather than trying to pigeon-hole every individual in one box or the other.