When photos of a tiny gray-and-peach bird with a blue tail were shared on Facebook Tuesday night 5 Dec 2023, the birding community was stunned. A Red-flanked Bluetail in Whiting, New Jersey, of all places? The next morning, about a dozen birders from three different states were on the scene to search for it. It took over an hour, but everyone finally got to see this hyperactive little Old World flycatcher in bluebird drag as she flitted around low to the ground and bobbed her tail. Over the next week, hundreds of birders from all over the ABA Area landed in a sleepy retirement village in the Pine Barrens to see the Red-flanked Bluetail.

Red-flanked Bluetail, a.k.a. Orange-flanked Bush-Robin, is a long-distance migrant with a breeding range that stretches from Japan and Kamchatka west across Siberia into Finland, where it is expanding. It winters in Japan, Korea, southern China, Thailand, and Myanmar. Red-flanked Bluetail is increasingly found out of range in the western ABA Area, as well as in western Europe. About half of the ABA Area’s records are from Alaska, where the species has been found in spring and fall on the Bering Sea islands and the Aleutians. In both seasons, migrants may drift across the Bering Sea on southwesterly winds from the Kuril Islands and Kamchatka. The bluetails found far beyond the Bering Sea in western Canada, the U.S., and Mexico in fall may represent misoriented migrants or storm waifs pushed across the Pacific. Away from Alaska, Red-flanked Bluetail has turned up in seven western states and provinces since 2011: British Columbia, Washington, Oregon, California, Idaho, Wyoming, and, spectacularly, Guerrero, where there was one in late winter 2021.

(Read more about the Red-flanked Bluetail in Guerrero in Michael Carmody’s Field Ornithology article here: https://www.aba.org/carmody2021/)

In Europe, Red-flanked Bluetail’s breeding range has been expanding westward into Finland, and sightings have become quite common as far west as Great Britain, where 40 years ago it enjoyed legendary vagrant status but now solicits yawns—a total of 148 records from 2007−2017 prompted the British Birds Rarities Committee to drop the species from its rarity list. Further afield, there are half a dozen records from Iceland since 2017, three of which occurred this fall around 21−22 Oct 2023.

So how did a Red-flanked Bluetail reach New Jersey? A direct flight to New Jersey from its breeding grounds would bring it across either the Arctic from far eastern Russia, or the North Atlantic from Finland—and the latter route seems plausible. A misoriented migrant from Finland heading northwest instead of southeast and traveling the same distance it should have traveled to the species’s usual wintering grounds in Southeast Asia could end up in New Jersey. Whiting, New Jersey and Mount Victoria, Myanmar are about equidistant (~4100 miles or 6600 kilometers) from Kuusamo, Finland in opposite directions.

Or the bird’s route from Finland to New Jersey may have been more circuitous. Earlier in the fall, just a few days before the Red-flanked Bluetails turned up in Iceland, southeasterly winds were streaming in directly from Great Britain, where the species is becoming more common.

Weeks later, in the days preceding the Red-flanked Bluetail’s discovery in New Jersey on 5 Dec, winds were favorable for flight from either Iceland or Scandinavia across the sea to Labrador. Winds over the North Atlantic usually flow west to east, but when the negative phase of the North Atlantic Oscillation (NAO) is active, powerful easterlies result, and on 28 Nov, the NAO dipped negative and stayed negative through 4 Dec.

Red-flanked Bluetails should be absent from Finland by late Nov, so the New Jersey bird may have begun its long journey earlier in the fall with a stopover in Great Britain before heading northwest to Iceland and then across the North Atlantic. After reaching terra firma in Labrador sometime between 29 Nov−3 Dec, it would have encountered strong northerly and northeasterly winds, carrying it to New Jersey on 4 Dec.

The split of Himalayan Bluetail from Red-flanked is worth mentioning here since separating the two can be near impossible. Formerly considered a subspecies of Red-flanked, Himalayan Bluetail is now thought to be a full species based on genetic evidence compiled over the last 30 years. Himalayan Bluetail inhabits the Himalayas and western China during the breeding season, and while birds across most of the range move up and down in elevation seasonally, the eastern population migrates south to Thailand and Myanmar in fall. Distinguishing female Red-flankeds and female Himalayans is very difficult at best, especially when a female turns up outside both these species’s ranges. However, given Red-flanked’s dramatic range expansion into western Europe, its established pattern of vagrancy to the ABA Area, and the fact that all specimens collected in North America prior to the split have been Red-flankeds (T. c. cyanurus per Howell et al. 2014), Red-flanked Bluetail is the expected unexpected bluetail here.

Recommended citation: Davis, Amy, & Feldstein, Steven B. 2023. First Red-flanked Bluetail in the Eastern ABA Area. North American Birds.

Sources:

“Bye bye Bluetail: Red-flanked Bluetail dropped by the BBRC.” https://www.rarebirdalert.co.uk/v2/Content/bye-bye-bluetail.aspx?s_id=47703832

Collar, N., E. de Juana, and D. A. Christie (2020). Red-flanked Bluetail (Tarsiger cyanurus), version 1.0. In Birds of the World (J. del Hoyo, A. Elliott, J. Sargatal, D. A. Christie, and E. de Juana, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.refblu.01

del Hoyo, J., N. Collar, and D. A. Christie (2023). Himalayan Bluetail (Tarsiger rufilatus), version 1.1. In Birds of the World (S. M. Billerman, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.himblu1.01.1

Howell, Steve N. G., et al. 2014. Rare Birds of North America. Princeton University Press, Princeton, New Jersey.

Lees, A. C., and Gilroy, J. J. 2021. Vagrancy in Birds. Princeton University Press, Princeton, New Jersey.

Amy Davis is Associate Editor of North American Birds and special issues of Birding, as well as Editor of ABA’s online Field Ornithology series and Regional Compiler for NAB’s Hudson-Delaware region. She supports community science, participates in various breeding bird atlases, and serves on two state records committees. A lover of fishing and pelagic birding, Amy resides in Forked River, New Jersey.

Steven Feldstein is an emeritus professor of atmospheric science at the Pennsylvania State University. He retired in January 2023. His area of research has been in large-scale atmospheric dynamics. Most of his birding has been in the Nearctic, and he has enjoyed many birding trips to the Palearctic, especially Israel and Korea. His research plans in retirement will be on the impact of the weather on bird migration.