ABA Area’s First Icterine Warbler at Gambell, Alaska
by Amy Davis
September 27, 2022
On 22 Sep 2022, Rodney Ungwiluk, Jr. found an ABA-Area first Icterine Warbler just north of the far boneyard at Gambell, St. Lawrence Island, Alaska. Icterine Warbler can be separated from its sister species, Melodious Warbler, by its long primary extension, pale secondary patch, and bluish leg color. Fortunately, this individual was extraordinarily well documented.
Icterine Warbler is a highly migratory species breeding in Europe and Central Asia, from western France and Scandinavia east to Kazakhstan. It winters in tropical Africa from Tanzania south to parts of Namibia and South Africa. The species regularly drifts across the North Sea to coastal England in fall. While many of Gambell’s vagrants drift in on westerlies from Russia’s Chukchi Peninsula (particularly in spring but in fall as well), this individual’s appearance seems to represent an extreme case of reverse or mirror-image migration.
Reverse migrants are thought to be at the mercy of defective inborn navigational systems compelling them to travel in the opposite direction of their conspecifics. Gambell lies atop an axis extending over the Arctic through Svalbard south to Ukraine (in the species’s breeding range) and Botswana (in the heart of its winter range). The midpoint between Gambell and Botswana is squarely within the breeding range of Icterine Warbler.
This Icterine Warbler is the highlight of an unforgettable early fall season in Alaska. In mid-Sep, both the Pacific North American teleconnection and the West Pacific pattern were positive, creating atmospheric conditions favorable for pushing Asian migrants overwater towards western Alaska. Then the remnants of Typhoon Merbok walloped the Aleutians before continuing north into the Bering Sea. Some of the rarities occurring on St. Paul Island in mid-late Sep 2022 include Jack Snipe, Spotted Redshank, Middendorff’s Grasshopper Warbler, Taiga Flycatcher, and Rustic Bunting. Elsewhere in the western Aleutians, recent reports include a Pacific “Fork-tailed” Swift, a possible Pin-tailed Snipe, both Brown and Red-backed shrikes, a Eurasian Skylark, an Amur/Siberian Stonechat, a Gray Wagtail, a Tree Pipit (ABA Area’s eighth), a Pechora Pipit, and a Yellow-breasted Bunting (which is globally endangered). And last but not least, two Eurasian Hoopoes (one living, one deceased) were found on St. Paul Island in the Bering Sea.
Davis, Amy. 2022. ABA-Area First Icterine Warbler at Gambell, Alaska. <https://wp.me/p8iY2g-dZp> North American Birds.
Lees, A. C., and Gilroy, J. J. 2021 Vagrancy in Birds. Princeton University Press, Princeton, New Jersey.
Howell, Steve N. G., et al. 2014. Rare Birds of North America. Princeton University Press, Princeton, New Jersey.
Feldstein, Steven, personal communication.
No stranger to ABA publications, Amy Davis has served as Sightings department editor at Birding and technical reviewer at Birder’s Guide. She was also photo editor for Pennsylvania Birds. Amy loves citizen science and volunteered extensively for breeding bird atlases in Pennsylvania, Delaware, and West Virginia. She resides in Forked River, NJ, and recently broke her home county’s big year record. When she’s not birding the Barnegat Bay, Amy studies nursing and plays classical piano.
Very nice write up on reverse migration and the Icterine Warbler! Thanks!
Just one correction:
Also notable were a Naumann’s Thrush at Adak on 24 September and a Citrine Wagtail (Alaska’s first) at Seward on 15 September.
Thanks for mentioning those! What a season you’re having so far!