Since the American Ornithological Society (AOS) issued its 58th Supplement to its Check-list of North American Birds in which Thayer’s Gull was relegated to a subspecies of Iceland Gull, there have been a number of questions from the Illinois birding community about the handling of Thayer’s Gull with regards to list submissions. The Listers Corner Committee (with the approval of the IOS Board) will be handling the Thayer’s Gull question in this manner:
- Thayer’s Gull will be countable for all 2017 year lists (state, county, etc.). Technically, one shouldn’t count it if it is first found after July, when the IOS Records Committee amended the official state list. See the official Illinois State List of Birds on the IOS Web site.
- Thayer’s Gull will be countable for all Big Days and Big Months through July 2017, but not afterwards.
- Thayer’s Gull should not be included with any submitted life lists (state, regional, county, sites, buddy, etc.). This pertains to any total submitted for inclusion in the 2017 Listers Corner.
- The Listers Corner Committee will not be going back and vetting any lists from the past. Even though we know for certain that some birders have Thayer’s on their lists, it would be impossible to apply retroactive adjustments in any kind of equitable manner. If a birder does not submit an updated number, the number on record will not be changed.
Questions or comments? Please contact the Listers Corner Committee.
Joe Lill – IOS Listers Corner Committee Chair