Ken and Maine birders:
Female and immature orioles are tough and perennially confounding. Some plumages of Bullock's and Baltimore are very similar, and the caption in the photo that Ken references (bottom of pg. 427 in Ned Brinkley's National Wildlife Federation field guide) says, "some young Baltimores very similar."
So, what is it about that field guide photo compared to Ken's photos of the bird in Maine that I see different and yet he sees as convincing for Bullock's? I think I have the answer. The photo in the field guide shows a bird with the brightest color in the maler and face, whereas the Maine bird shows the brightest color in the breast and throat. [The malar is the tract of feathers extending behind the mandible (= "lower mandible") below the ear coverts.] The bird in the field guide clearly shows the breast as duller than the malar and face, whereas the Maine bird has the breast showing the brightest color and the crown and face being rather dull by comparison.
Look at Ken's photo here (29 January):
http://flic.kr/p/jB3REj
One can see that the breast, especially the center of it, is the brightest area of color. The cheeks, hindneck, and crown are a dull olive with a wash of yellow. The malar color in this and Ken's other photos (http://flic.kr/p/jvQ5C7 and http://flic.kr/p/jB2RuQ) is SIMILAR or DULLER in brightness to the breast color. The overall effect on Baltimore is a more hooded look, the crown and sides of face cloaked in a more or less uniform wash of greenish olive, duller than the breast and throat. Baltimore Oriole can show some brighter color in the forehead, but Bullock's should show, at least in some angles, a darker line behind the eye that sets-off the paler supercillum ("eyebrow"). I admit that the photo on page 427 of the NWF guide does not show this well. I think it is a photographic effect; the bird is in strong light, washing out some subtle features. This is one reason why reliance on a single photo for identification, or as reference for identification, can lead one astray.
No doubt one can find many images to compare online, but here is one of mine showing a female Bullock's Oriole that I found on a Santa Barbara Christmas Count over a year ago:
http://flic.kr/p/jHT3Hu
Not a great photo, but it shows the key points that Bullock's should show, especially a bird we would want to claim as occurring out of range in Maine. See how my Bullock's shows a brighter orange supercillium set-off by a dark line behind the eye AND a bright orange malar that is more intensely colored than the breast. The cheeks and sides of hindneck are also brighter than the crown and the breast. In some positions, the breast would appear brighter, but then only as bright as the malar and never more intensely colored. The whole effect of a Bullock's is a bird with a colorful face versus Baltimore with its duller and more uniform head and face compared to a brighter breast. An additional character shown by the Santa Barbara bird is the dull and grayish undertail. Not all Bullock's are this dull on the undertail but most are. Baltimore nearly always shows distinctly brighter (yellowish or orangish) well-demarcated undertail coverts (or crissum).
These photos of a dull Baltimore Oriole by Jeremiah Trimble show what looks like a similar bird to the York oriole:
http://flic.kr/p/aMi3mi
http://flic.kr/p/aMi3rZ
I don't think anyone knows for sure what these "dull" Baltimore Orioles are. We assume, and some field guides now tell us(!) they are immature females in their first winter, but there is no confirmation of that (many are definitely immature; the sex is rarely, if ever, confirmed). Some people have suggested that such dull birds are the result of poor diets. Again, no confirmation that is the case. There are many hybrids and intergrades between Bullock's and Baltimore Orioles. We know this based on character rich patterns expressed by adult males. Intergrades would be nearly impossible to confirm with immature and dull birds. So, I often leave that open as a possible explanation for some of these birds that show a pentimento of Bullock's in them. We know that intergrades make it to New England. Here is one that was in Connecticut and photographed by Mark Szantyr: http://bit.ly/1cNleZH (several photos of this male--note wing pattern and tail pattern, with dark tips to outer rectrices).
Lastly, in full disclosure, I was a reviewer for the field guide that Ken cited (see page 489). There are many errors in there we regret (some not our fault; some overlooked), but Alvaro Jaramillo, Paul Lehman, and I did read and edit the entire guide.
Louis Bevier
Fairfield
On Feb 2, 2014, at 7:26 PM, Ken DiBiccari <kendibiccari@roadrunner.com> wrote:
> I have not returned to try and get more images of the Oriole but my belief of it being a Bullock's Oriole comes from my researching six different
> field guides on the bird and after seeing and reading the description and looking at the photograph of the adult female Bullock on page # 427 of the National Wildlife Federation - Field Guide To - BIRDS - Of North America by.....Edward S. Brinkley, that the photograph on the bottom of that page is so convincing in every detail that I truly believe it is indeed a Female Bullock's Oriole. If at all possible you can get access to this particular reference guild, I think you can see why I have come to this conclusion. I will try again soon to get more images of the bird if it is still there. I do have a short video of this bird in the tree where I took the still images but I don't know how to post it on line.
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