Mystery Bird: Yellow-billed Loon, Gavia adamsii

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[Mystery bird] Yellow-billed Loon, Gavia adamsii, photographed in Arizona. [I will identify this bird for you tomorrow]
Image: Richard Ditch, 2008 [larger view].

Date Time Original: 2008:05:23 06:41:10
Exposure Time: 1/350
F-Number: 8.00
ISO: 320

Rick Wright, Managing Director of WINGS Birding Tours Worldwide, writes:
Here’s a long, lean bird floating low in the water. All waterfowl — in the strict sense: ducks, geese, swans — are obviously more buoyant, and with the exception of the larger mergansers, obviously shorter-bodied. The contenders? Grebes, loons, cormorants.
Adult cormorants are either blackish or strikingly black-and-white; young birds can be paler, but I can’t think of any species at any age as pale as this bird. Cormorants are also notably longer-tailed, while on our mystery bird the tail is invisible beneath the folded wingtips. The neck is too thick, the head too large, and that amazing bill too thick and sharp for a cormorant, too.
The back three quarters or so of this bird — low-riding, silvery, tailless — would be all right for a grebe, but again, that thick neck, big head, and powerful bill just don’t fit any member of that relatively svelte bunch of pinheaded birds.
Everything fits, though, for a loon. Of the five extant species, we can quickly rule out Red-throated simply on this bird’s massive aspect. The paleness of the head and neck are quite unlike Common Loon, which even in its dullest plumage shows a dark crown, nape, and at least partial neck bands. This bird is also far too pale, too thick-necked, and too huge-billed for either of the black-throated species. We’re left with Yellow-billed Loon, or White-billed Diver as its known in much of its range — and it’s probably time to look at that bill.
This is a beak of epic proportion, with a ridiculously sharp gonydeal angle making the bird look as if it were smiling (perhaps it is). The gape extends way back on the “face” to under the eye. And the culmen — the ridge of the upper mandible — is dull yellowish-white, quite unlike the dark culmen of a Common Loon.
Not that many years ago, Yellow-billed Loon was a high Arctic specialty. With more people looking, and better information available on the species’ identification, Yellow-billeds are being found in winter at low densities throughout North America. At a distance, the pale head and neck and huge bill, shown so well in this photo, are the first tip-off.
Review all mystery birds to date.


About GrrlScientist

grrlscientist is the pseudonym of an evolutionary biologist and ornithologist who writes about evolution, ethology, and ecology, especially in birds. After earning a degree in microbiology (thesis focus: virology) and working at the Fred Hutchinson Cancer Research Center in Seattle, she earned her PhD in zoology from the University of Washington in Seattle, where she studied the molecular correlates of testosterone and behaviour in white-crowned sparrows. She then worked a Chapman Postdoctoral Fellow at the American Museum of Natural History in New York City, where she studied the speciation and distribution of lories and other parrots throughout the South Pacific Islands. A discarded scientist, she returned to her roots: writing. Formerly hosted by The Guardian (UK), she now writes about science for Forbes and for the non-profit think tank, the Evolution Institute and she writes podcasts for BirdNote Radio. An avid lifelong birder and aviculturist, she lives with a flock of songbirds and parrots somewhere in Germany.
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0 Responses to Mystery Bird: Yellow-billed Loon, Gavia adamsii

  1. Akheloios says:

    I believe that sir, is a duck.

  2. My first thought was yellow-billed loon. After consulting the field guide, I don’t know; that would be a really unusual bird for Arizona; common loon would be much more… well… common. And they look a lot alike. But if you tied me down and tickled me with a feather, I’d say it still looks more like a yellow-billed than a common to me.

  3. RM says:

    Loon is as close as I can get. It must be a young bird.

  4. Hilary says:

    It’s got the undershot profile of a loon, but it doesn’t match any of the pictures in Sibley. If it’s yellow-billed, why is the bill gray? If it’s common, where’s the collar? Looking forward to the answer on this one!

  5. Chuck says:

    This is almost certainly a Common Loon. A Yellow-billed Loon would have a distincive spot to the rear of the eye and diffrently shaped white cheek area. The only thing I might question is the slight yellowish tinge to the end of the bill.

  6. Jim says:

    The relatively straight culmen and light color sure looks like the bill of a Yellow-billed Loon. The pale face and head shape look good despite the lack of a distinct dark mark behind the eye. I’ve never seen a Common Loon that looks anything like this. Is the date May 23 in Arizona for the bird? That bothers me, but the bill and head shape say Yellow-billed Loon.

  7. yes, that’s the correct date for the image (as provided by the photographer).

  8. aedis says:

    Surgeons v. Orcadians.
    I’ll go for White-billed Diver. G. adamsii named after English surgeon Edward Adams.
    Slightly upturned ivory bill and a lot lighter than Great Northern Diver. (G. immer named after the Orkney word for the diver. [SCD])
    Nape is lighter than back. Its darker on Great Northern Diver.

  9. The Ridger says:

    I’m gonna go with yellow-billed loon, though the common loon does make more sense for Arizona. Still, nothing says somebody can’t be out of pocket.

  10. bobk says:

    Yellow-billed Loon.
    Best advice I ever received was to read the text in the field guides: bill angled up with outer half pale, peak of back at mid body, relatively thick neck.
    By the way, what came first, the noun loon or the adjective? And do they have the same ancestry?

  11. Amarillo says:

    It’s a Yellow-billed Loon.

  12. Albatrossity says:

    Interesting bird. My first-glance ID was Yellow-billed Loon, although it is an odd time of the year in an odd part of the country for this bird to show up! That ID is based on the bill color, bulk and shape, and the fact that it carries the bill uptilted. This bird also lacks the dark line that would be on the culmen of a Common Loon in this plumage. It is a pale bird overall, so I am not bothered by the lack of a dark auricular patch; this is a very faded bird.
    In general, physical characters (size and shape of bill) and behavioral characters (uptilted bill) are usually better guides than plumage characters, particularly in a single photograph. I’ve seen enough bizarre plumages in common birds to know that plumage can be very misleading. It’s a lot harder to find a bird with an unusually-shaped bill or odd behavior that mimics another species.
    So I’m sticking with the first-glance ID – Yellow-billed Loon.

  13. Fia says:

    I’d also go for the Yellow-billed loon. And I don’t know much about when what species shows up in Arizona, but it seems a bit bizarre. Am curious for the solution.

  14. JohnB says:

    That’s a very heavy bill for a Common Loon, even considering the angle might make it look heavier than it really is. I’ll say Yellow-billed.

  15. The Ridger says:

    Loon = a crazy person comes from Old English loun, meaning a simpleton or an idler and related to loafer
    Loon = a diving bird comes from Norse lom, from lomr meaning lament; the English spelling with N is probably influenced by the other loon.
    And you have to factor in lunatic, of course, which came to us from Latin via French (lunatique, from Late Latin lunaticus, from Latin luna) and ultimately from a word which meant shining.

  16. This was a very unexpected bird for the place (Tempe Town Lake, near ASU east of Phoenix), and time of year (triple digit temperatures). I went to see and photograph the bird on three consecutive days before having it close enough; the following morning it departed.
    But this was not my first Yellow-billed Loon for AZ – I’d driven all the way to Lake Havasu on the Colorado River on AZ’s western edge to see one on March 5, 2002. That was a strange enough setting (not far from the relocated London Bridge). But Tempe Town Lake is even stranger – a man made lake in the dry Salt River bed, filled with water routed all the way from the Colorado because the Salt River is dammed upstream and diverted to agricultural use in central AZ.
    There’s more information on the AZFO photo documentation web site: