Sightings:
- Short-billed Gull (adult). Calgary County, Alberta. 01 September 2021.
- Little Gull (adult). Power County, Idaho. 01 September 2021.
- Sabine's Gull (adult). Rankin County, Mississippi. 01 September 2021.
- Common Gull (2nd cycle). Cape Breton County, Nova Scotia. 02 September 2021.
- Heermann's Gull (3rd cycle). Duval County, Florida. 02 September 2021.
- The same waif on the Atlantic coast since August 2019.
- Sabine's Gull (juvenile). New Haven County, Connecticut. 03 September 2021.
- 3rd State Record.
- Short-billed Gull (juvenile). North Battleford County, Saskatchewan. 04 September 2021.
- Black-legged Kittiwake (juvenile). New Haven County, Connecticut. 04 September 2021.
- California Gull (2nd cycle). Lake County, Illinois. 04 September 2021.
- Black-legged Kittiwake (juvenile). Franklin County, Pennsylvania. 05 September 2021.
- Black-headed Gull (adult). Ocean County, New Jersey. 06 September 2021.
- Little Gull (adult). Osage County, Kansas. 07 September 2021.
- Black-legged Kittiwake (juvenile). Marion County, Indiana. 08 September 2021.
- Slaty-backed Gull (3rd cycle). Kenai Peninsula County, Alaska. 08 September 2021.
- Franklin's Gull (1st cycle). York County, Maine. 09 September 2021.
- Little Gull (juvenile). Jefferson County, Illinois. 09 September 2021.
- Little Gull (juvenile). Natrona County, Wyoming. 10 September 2021.
- Franklin's Gull (adult). Prince William County, Virginia. 10 September 2021.
- Yellow-footed Gull (1st cycle). De Baca County, New Mexico. 10 September 2021.
- Apparent 1st State Record.
- Yellow-footed Gull (1st cycle). Mohave County, Arizona. 10 September 2021.
- Apparent 2nd State Record.
- Little Gull (juvenile). Natrona County, Wyoming. 10 September 2021.
- Apparent 3rd State Record.
- Heermann's Gull (2nd cycle). Umatilla County, Washington. 12 September 2021.
- Laughing Gull (2nd cycle). Onondoga County, New York. 15 September 2021.
- Great Black-backed Gull (2nd cycle). Lyon County, Kentucky. 17 September 2021.
- Black-legged Kittiwake (juvenile). Rockingham County, Virginia. 17 September 2021.
- Little Gull (juvenile). Barton County, Kansas. 17 September 2021.
- Sabine's Gull (juvenile). Rockingham County, Virginia. 17 September 2021.
- Lesser Black-backed Gull (adult). Sitka County, Alaska. 18 September 2021.
- Laughing Gull (2nd cycle). Colfax County, New Mexico. 18 September 2021.
- Franklin's Gull (adult). Bergen County, New Jersey. 21 September 2021.
- Sabine's Gull (juvenile). Forsyth County, Georgia. 21 September 2021.
- Sabine's Gull (juvenile). Desha County, Arkansas. 22 September 2021.
- California Gull (adult). Dubuque County, Iowa. 25 September 2021.
- Little Gull (juvenile). Walla Walla County, Washington. 26 September 2021.
- Slaty-backed Gull (adult type). Comox-Strathcona, British Columbia. 28 September 2021.
- Iceland Gull (adult). Shelby County, Illinois. 28 September 2021.
- Lesser Black-backed Gull (adult). San Diego County, California. 28 September 2021.
- Heermann's Gull (3rd cycle). Beaufort County, South Carolina. 30 September 2021.
- The same waif on the Atlantic coast since August 2019.
Notes:
1. Most unusual this month is two reports of Yellow-footed Gull at inland lakes in the Southwest. Both 1st cycles, and both reported on the same day, hours apart. The birds lingered allowing many people to leisurely add this species to their AZ & NM state lists. These reports, if accepted, would be a 1st state record for New Mexico, and a 2nd state record for Arizona. The New Mexico sighting would be the easternmost occurrence for the species.
2. Ample Sabine's Gulls were reported inland this month, with an above average occurrence of adults. Little Gulls were also reported in higher than usual numbers west of the Mississippi River.