Monthly Notables October 2019

Sightings:

• Black-headed Gull (adult type). Juneau County, Alaska. 02 October 2019.
• Little Gull (juvenile). Cass County, Minnesota. 02 October 2019.
• Franklin's Gull (1st cycle). Lycoming County, Pennsylvania. 04 October2019.
• First County Record.
• Laughing Gull (1st cycle). Montmagny County, Quebec. 05 October 2019.
  
• Slaty-backed Gull (3rd cycle type). Grays Harbor County, Washington. 05 October 2019.
• Great Black-backed Gull (adult). Mobile County, Alabama. 06 October 2019.
  
• Thayer's Gull (1st cycle). Fairbanks North Star County, Alaska. 07 October 2019.
• Great Black-backed Gull (adult). Keith County, Nebraska. 08 October 2019.
• Ivory Gull (adult). North Slope County, Alaska. 08 October 2019.
• California Gull (adult). Berrien County, Michigan. 13 October 2019.
• Sabine's Gull (juvenile). Aleutians West County, Alaska. 13 October 2019.
• Late record for St. Paul Island, by 11 days.
• Mew Gull (adult). Washington County, Colorado. 14 October 2019.
• Black-tailed Gull (2nd/3rd cycle type). Jefferson County, Washington. 17 October 2019.
• 8th(?) State Record, pending acceptance.
• Glaucous Gull (1st cycle). Cook County, Illinois. 19 October 2019.
  
• Laughing Gull (adult type). Cochrane District, Ontario. 19 October 2019.
• Black-legged Kittiwake (2nd cycle type). Fairfield County, Connecticut. 19 October 2019.
• A Review List Species for CT.
• Glaucous-winged Gull (1st cycle). Salt Lake County, Utah. 21 October 2019.
  
• Black-tailed Gull (2nd cycle). La Haute-Cote-Nord County, Quebec. 21 October 2019.
• An extraordinary plumage likely unrecorded in eastern North America. Most upperparts new (2nd basic?). P1-P5 new, 2nd basic. Outer primaries, secondaries and lesser upperwing coverts old.
• Slaty-backed Gull (adult). Aleutians East County, Alaska. 21 October 2019.
  
• Black-tailed Gull (adult). San Francisco County, California. 23 October 2019.
• 1st Farallon Islands Record.
• Lesser Black-backed Gull (adult). San Diego County, California. 23 October 2019.
• California Gull (2nd cycle). Northumberland County, Ontario. 23 October 2019.
• Laughing Gull (adult type). Sudbury County, Ontario. 24 October 2019.
• Black-legged Kittiwake (juvenile). Marquette County, Michigan. 24 October 2019.
• Heermann's Gull (1st cycle). Brevard County, Florida. 25 October 2019.
• Continuing 1st county record first sighted in August 2019. 
• Lesser Black-backed Gull (adult). North Okanagan District, B.C. 28 October 2019.
• Glaucous Gull (1st cycle). San Francisco County, California. 30 October 2019.

Notes:

1. The highlight this month was the 3 reports of Black-tailed Gull. The species is always exceptionally rare in the ABA area, making October 2019 a very noteworthy event. Most interesting is the young bird photographed in Quebec with a flock of Ring-billed Gulls. This individual was about 4 months behind schedule in its 2nd prebasic molt. 

October 2019 Quiz

Age: A rather standard 1st cycle, large gull, with what appears to be all juvenile upperparts.

Identification: Our October Quiz is a good example of why knowing date and location is indispensable information at times. This individual was photographed on the Kenai Peninsula along the Cook Inlet in late August. The most expected taxon here, at this time of year, consists of Herring x Glaucous-winged hybrids (so called Cook Inlet Gulls). Armed with this information, we must eliminate that mix first and foremost.

There are a number of features that we may attribute to Glaucous-winged, such as the plain and paler upper tail, pale edges to the primaries, high eye placement, grayish-brown plumage aspect and fine upperwing covert pattern. Less obvious are the Herring features, consisting of a paling bill base, notched scapular pattern, and perhaps most important, the darker primaries.

Two confusion taxa that may be considered away from this hybrid zone, and/or at a later time in the year, are Thayer's and Glaucous x Herring hybrid.

For Thayer's, we'd generally expect an all-dark bill without the wide base. Also, this individual appears big-bodied with higher than normal eye placement and a shorter primary projection (which admittedly may be due to posture or growing wings). Furthermore, the lesser and median coverts on this bird appear too "busy" with wavy markings that aren't as boldly patterned as is typically found in Thayer's.

As for Glaucous x Herring hybrids, that combination is difficult to rule out structurally. However, plumage aspect on that hybrid is often brighter with a frostier appearance, with more white-centered upperparts, as opposed to the grayish tones seen in some Glaucous-winged x Herrings. Again, location and time of year support a Cook Inlet Gull.

Anchor Point, Alaska. August.