Mystery Bird: Flying Gull-billed Tern, Sterna nilotica

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[Mystery bird] Gull-billed Tern, Sterna nilotica, photographed flying over Bolivar Flats, Texas. [I will identify this bird for you tomorrow]
Image: Joseph Kennedy, 6 June 2008 [larger view].
Nikon D200, Kowa 883 telescope TSN-PZ camera eyepiece 1/2000s f/8.0 at 1000.0mm iso400.

Read a detailed analysis for identifying this species below the fold …


Rick Wright, Managing Director of WINGS Birding Tours Worldwide, writes:
Compare this bird’s shape and structure to the Sandwich Tern in a recent quiz. You’ll notice right away that the legs are thick and the bill heavy, broad, and powerful — from this angle, especially noticeable at the base. Instead of the elongated body and “swan neck” of Sandwich , this bird is nearly terete — like the cardboard tube from a toilet paper roll — with a massive, thick neck and a decidedly angular head.
All classic features of Gull-billed Tern, as is the broad dark trailing edge of the primaries. Bill color is a nice supporting mark in this photo, but it’s worth noting that Olsen and Larsson’s Terns warns that the extreme tip of the bill can be pale.
In the field, Gull-billed Terns stand out nicely because of their habitat and habit. They aren’t often seen over the ocean, preferring instead to hunt the salt marshes. And that hunting is accomplished not by plunge-diving, the usual mode of attack of large terns, but by swooping and skimming, plucking crabs and other small invertebrates from the ground as they pass.
Review all mystery birds to date.

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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: Flying Gull-billed Tern, Sterna nilotica

  1. Lindsay says:

    I’m thinking Gull-billed tern. The black hood, the lack of a yellow tip to the beak, the black beak…

  2. Jim says:

    Gull-billed Tern because of the thick apparently all black bill, black legs and feet, all light tail without any darker color, and lacking the longer outer tail of a Common, Arctic, Roseate, or Forster’s Tern which I think would even show up when the tail is fanned. The underwing pattern eliminates some of the more exotic terns. Sandwich Tern would have a more slender bill with a yellow tip. The location falls within Gull-billed’s expected range.

  3. JPS says:

    I say gull-billed tern too.

  4. Smilodon says:

    I’m gullible too, so I’ll agree with everyone else.

  5. Bill Voss says:

    Make that five for Gull-billed. Since it’s a June photo, it would be in breeding plumage.

  6. bobk says:

    Not present.
    OK, everything else looks like a Gull-billed but that bill just doesn’t say Gull to me. I remember the first time I saw a Gull-billed and I thought wow that really does look like a gull’s bill. And also, There seems to be too much black, too far below where I think the eye is and too broad around the back of the neck. And the black seems to have white intrusion on the side of the neck like a Roseate Tern. I wish the tail wasn’t flared – it’s hard to tell how deep the notch is. Sense I wasn’t here to make an earlier ID, I think I’ll stall and take the glory if it’s not a Gull-billed (who said there’s no politics in bird watching).

  7. Ian says:

    One good tern deserves another, so will we see one like this tomorrow? The bird-en is on GrrlScientist to put down her Avian water and get to work. But don’t overdo it. Remember, three shrikes and you’re out….

  8. Fia says:

    Gull-billed tern. I like terns, really.