Monday, August 31, 2009

Quiz #315 (2009-3-10) Answer

Click the picture for a larger view.

Answer by Tony Leukering

For a change, we can see our quiz bird's head and almost all other critical parts, so we ought to be able to get this one correct rather quickly. Ah, but the beastie is flying, and that will put some off. That the bird is an oriole -- with its pale-based and quite-pointed bill and color pattern of yellow-olive body and blackish wings and tail -- seemed obvious to respondents, but which particular oriole was a question of some uncertainty.

When one is looking at an oriole, there are a couple of macro-scale features that can quickly reduce the number of options from the list of 10 ABA-area oriole species (see rules for link). The first is whether the bird is a yellow oriole or an orange oriole. There are five truly orange species of oriole -- that is, they do not sport a yellow or yellowish plumage at any age -- on this list (Streak-backed, Bullock's, Spot-breasted, Altamira, and Baltimore) and two truly yellow orioles (Audubon's and Scott's). Then there are the 'tweeners, those species that either have at least one age/sex class flaunting a yellow or yellowish plumage but with other plumages lacking yellow (Orchard) and those that cannot decide whether they want to be yellow or orange (Hooded and Black-vented). We can quickly rule out the five truly orange orioles.

Another couple of excellent wedge characters are wing pattern and tail pattern. Our quiz bird seems to have a solid black tail, but looking at the far rectrix, which appears greenish, suggests that our impression of blackness may be due to shading rather than pigmentation. However, that tail does seem to lack the white tips of Scott's Oriole tails and its length is also different from the short tail typical of Scott's. The quiz beastie has black wings with thin, pale wingbars, which rule out Black-vented. The above should leave us with only three options, Orchard, Hooded, and Audubon's. As it's the most-limited, range-wise, in the ABA area, we'll start our final elimination process with Audubon's. That species does have a rounded or graduated tail as on our quiz bird, but it also sports a short, straight bill at odds with our quiz bird. In fact, that feature also eliminates Orchard, which also has a shorter, squarer tail than does our quiz bird. I took this picture of an immature Hooded Oriole at Goleta, Santa Barbara Co., CA, on 28 July 2009.

Emerging from the carnage of this week's quiz, Al Guarente, with nine correct, is in sole possession of first place in the quarter's competition, with Mark Dettling, Robert McNab, and Peter Wilkinson right behind with eight correct. One correct answer was submitted 48 minutes past the deadline. Sorry.

Incorrect species provided as answers:
Orchard Oriole - 9
Scott's Oriole - 3

The 6 of 18 providing the correct answer:
Mark Dettling
Al Guarente
Andy Dettling
Peter Wilkinson
Margie Joy
Robert McNab

Answer: Hooded Oriole