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    #ABArare – Oriental Cuckoo – Alaska

    All eyes turn to western Alaska in early June, as intrepid guides and tour participants comb the Bering Sea Islands and the Aleutians in search of Asian overshoots. While in the past, far Attu was often the singular target, now that the island is more difficult (though not impossible!) to reach the spotlight has turned more towards the Pribilofs and St. Lawrence as spring destinations. And for good reason, both sites have seen an impressible list of rarities in recent years.

    Prologue aside, one of the early highlights is an apparent Oriental Cuckoo (ABA Code 4), discovered by Glen Davis and photographed by Cory Gregory (both with St. Paul Island Tours) on June 4 and continuing the next day, on St. Paul Island in the Pribilofs.

    photographed by Corey Gregory, used with permission

    photographed by Cory Gregory, used with permission

    More photos are available at Cory’s flickr page.

    St Paul Island is accessible by air via several Alaskan airports, most notably Anchorage, on Penair Airlines.

    Oriental Cuckoo is known in the ABA Area from around 10 records and 5 specimens, exclusively from the Bering Sea Islands and Aleutians. Field identification of the species is extremely difficult, given to its similarity with the more regularly occurring Common Cuckoo.  In fact, this bird was identified in the field as a Common Cuckoo before photos obtained by Cory Gregory suggested otherwise upon examination. Though the distinctions between the two remain poorly defined, adult Oriental Cuckoo tends to have courser bands on the breast and a buffier belly and undertail coverts.

    According to Scott Schuette, this is the 4th record of the species on St. Paul, and the first since 2004.

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    Nate Swick

    Nate Swick

    Nate Swick is the editor of the American Birding Association Blog. A long-time member of the bird blogosphere, Nate has been writing about birds and birding at The Drinking Bird since 2007, but can also be found writing regularly at 10,000 Birds. In the non-digital world, he's an environmental educator and interpretive naturalist. Nate lives in Greensboro, North Carolina, with his wife, Danielle, and two young children, who are not yet aware that they are being groomed to be birders.
    • Cory Gregory

      The bird was still present yesterday, June 7.

    • Paul Lehman

      Actually, underpart barring differences between these two species is likely over-rated, and there is substantial overlap. One potential important difference is underwing pattern: slightly bolder / more contrasty in Oriental, though this is hard to see in the field and is best analyzed using good flight shots. Also, on average, Oriental averages shorter billed and darker gray above. There are a few ID papers out there concerning these two species, including one I authored a number of years ago for the British publication “Birding World.”

      –Paul Lehman, San Diego

      • http://blog.aba.org/ Nate Swick

        Good stuff. Thanks, Paul.

      • John Puschock

        I looked at the Burke Museum’s collection of Common and Oriental Cuckoo spread wings. Oriental has fewer white spots/bars on the underside of the primaries, though there seems to be a little overlap. Adult Orientals largely had five white spots on the outermost primary while adult Common had six. Immatures of both species tended to have an additional spot, so six on Oriental and seven on Common.

        I know there’s one paper out there that talks about the number of white spots on the primaries overall, but I don’t know if any talk about the outermost primary specifically. The latest version of the National Geographic guide shows Oriental with fewer spots, but it’s not talked about in the text. I don’t think any other guides shows or talks about this.

        Cory Gregory’s photos show five spots on the outer primary, so consistent with Oriental. Furthermore, Oriental is noticeably smaller in a museum drawer. The photos appear to show a smaller bird to me, too, but I’m biased at this point. The photos also show some brownish coloration on the upper breast, so I’m guessing this is a female.

    • Mike Danzenbaker

      I’ve just returned from Mongolia where I was able to observe and photograph both species, sometimes at the same sites. My personal preliminary conclusion is that there may be no single reliable criterion on which to make a visual, not-in-hand field ID, and I have left all non-vocalizing individuals unidentified for now. Even aging and sexing is not straightforward in many cases. I looked mainly at underpart barring, lower belly / UTC color, upperpart darkness, rump/UTC color relative to the back, soft parts and head/bill structure. I haven’t yet examined folded primary spotting. Perhaps detailed underwing photos (which I didn’t obtain) might prove useful; there are some examples of these online, but even these I find murky. I would have liked to have had both species pose for me side-by-side, but they weren’t keen on doing this.

      I heard second-hand from a Swede last week that Finland recently re-evaluated its records of silent Oriental Cuckoo and rejected them all. I couldn’t find any mention of this online and so you could take this with a grain of salt.

      I say all this not to cast any aspersion on the ID of the bird at hand (the details of which I don’t know), but rather to urge extreme caution with these species in general. I’m not sure I know of any more difficult field ID problem.

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