Wednesday, May 29, 2013

Ternover: Your May Quiz Answer

Sandwich Tern. Note that the outer retrices, while not of Barn Swallow proportions, are significantly longer than the rest of the tail. Dry Tortugas National Park, FL.

Time for the quiz answer! What quiz? This quiz! We had guesses for Caspian, White, Royal and let's cut to the chase.

First, the bird is obviously a tern. What else would it be? 

Since I am the Number 7 birder in the United States (as opposed to the galaxy), you could probably deduce that I wasn't going to be a total ass and pick some tern from India to show if you could figure out this was a tern, you are familiar with the playing field. So what should we start looking at?

Caspian Tern. Terns are not supposed to be ugly, but nobody told this beast. Poe Road, south end of the Salton Sea, CA.

There are three things to look at in the quiz photo: tail shape, wing pattern and foot color. Anything about structure is subtle at best, given the unusual pose and lack of a head to complete the picture. So what do we have? A tern with black feet, a narrow edging of black on the primaries, and a very short tail.

The black in the wings immediately eliminates White Tern from the field of candidates, and the lack of extensive black patches in the primaries quickly eliminates Caspian Tern as well. Least Tern has black along the leading edge of the wing, and Forster's/Common/Arctic/Roseate all have longer tails. Sandwich Tern would be a good fit, but the tail is too short even for that species.

Royal Tern. That's a pretty short tail...but also strongly forked. Border Field State Park, CA.

Royal Tern. This young bird does not have completely haggard flight feathers, but it does have distinct pale inner webs to the primaries, unique to juveniles of this species. Dry Tortugas National Park. 

So how about Royal Tern? It's a bird that can have black feet, limited black on the underwing and a short tail. A damn good guess, I reckon.

While Royal Tern is an excellent guess...its wrong! The tail of our quiz bird is simply too short and shallowly forked. What ABA Area tern has a tail like that? Gull-billed, of course.

Gull-billed Tern is the correct answer to this month's photo quiz...props to Carrie and Taxman for giving the correct answers. These Gull-billed Terns were photographed at the Tijuana River Mouth, Imperial Beach, CA.

Although details are scant, the San Diego Bay Gull-billed Tern population (which the above birds are/were a part of) is undergoing "a significant mortality event" other words, tons of them are dying, and for no obvious reason. Considering how rad these birds are, and the very small population these birds have in the western U.S., let's hope we get some answers soon.

In slightly better news, you can actually find Gull-billed Terns in India. Gotcha!