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QUIZ GULL #14 (with answer below)
ANSWER: The correct answer is first year Kelp Gull.
Letís begin by ageing the bird. It appears to be a young bird, but probably beyond juvenile plumage based on the dark back feathers and the whitish head. The coverts and rectrices are quite worn, suggesting that the bird has carried these juvenile feathers for much of a year. Based on gaps in the primaries and secondaries, it looks as if its second pre-basic moult is just beginning. Thus, itís in first summer plumage just beginning to moult into second winter.
Now letís eliminate some species from contention. This is a large bulky bird with all dark wings and a remarkably white head given its young age. That eliminates the smaller gulls (Ring-billed, Common, Mew, Kamchatka), the pale gulls (Glaucous, Iceland, Glaucous-winged, Thayerís), and those with obvious pale windows on the inner primaries (all the Herrings, Vega, and Slaty-backed). We can also eliminate California and Black-tailed, which would not show this much black in the bill.
Letís move to the tail. It is basically black with some white barring at the bases of the outer rectrices. Great Black-backed, Lesser Black-backed, Baltic, and Mongolian all show white at the bases of the rectrices. Yellow-legged, Caspian, Heuglinís, Steppe (Baraba) Gull, and Armenian all have a broad enough tail bands that weíll keep them in (but weíre being generous with some of these). But if we focus on the back, which is fairly dark with some very dark-centered feathers coming in, and the greater secondary coverts, which are remarkably solid and unmarked, we pretty much eliminate these species, which are either paler-mantled or have checkered greater coverts.
Weíre down to Western, Yellow-footed, and Kelp. The large, bulky size and apparently large bill (although itís hard to be sure of its exact shape because itís partly open) also fit well with these species. We can safely eliminate Western; this bird is too white-headed at an early age. Yellow-footed and Kelp are fairly similar at this age. Yellow-footed actually has a nearly solid black tail and should not show this much white in the outer rectrices. That leaves us with only Kelp Gull.
This bird was photographed November 8 in Chile by Don DesJardin and proved to be the most difficult gull quiz by far, with only 1 in 25 guessing correctly.
|GUESS||# OF VOTES|
|Kelp Gull||1 (4% correct)|
|Great Black-backed Gull||11|
|Lesser Black-backed Gull||2|