Wednesday, January 13, 2016

Mystery Oriole

I was reminded this past week of how hard it can be to identify birds. Field guides often show just a few plumages of most species, leaving inexperienced birders with the notion that identification is straightforward. Some gulls take up to four years to reach adulthood and each year of that gull’s progress from juvenile to adult has a very different plumage. Shorebirds have adult breeding, adult non-breeding, and juvenile plumages. Most field guides don’t have enough room to depict all of the various plumages that a birder may encounter within a single species.

Inexperienced birders may not recognize that and be misled into thinking all the different looks of a species can lie within the pages of their favorite guide.

Orioles can pose some exceptionally tough identification challenges. Baltimore orioles have adult male, adult female, immature male, and immature female plumages. But there’s more… there can be a tremendous amount of variability within each plumage, especially in the immature birds. Add another species into the mix, like a Bullock’s oriole, that does rarely occur here and can appear superficially similar to a Baltimore, and you can be presented with really tough identification challenge.

An oriole was photographed in Charlotte last weekend that presented just such a challenge. Very experienced and highly respected birders across the state were divided on the identity of this immature female bird. Some staked out in the Baltimore oriole camp while others thought it might be a much rarer Bullock’s oriole.. 
What complicates this identification is the overall drabness of the bird. There are some fairly bright yellow areas but these are restricted in size compared to a typical Baltimore oriole of the same age. Further, there are characters that suggest Bullock’s oriole and some that seem more suggestive of Baltimore. Sometimes the answer can come down to the shape of the wing bars or overall brightness of the yellow.  I suspect it is a drab Baltimore oriole immature. The odds favor it but we probably will never know for sure.

If all of our birds looked like adult males, identification would be easy and essentially non-challenging. Orioles would pose no ID problems between the two species, Baltimore and Bullock's.
The adult male Baltimore is unmistakable and is the most expected oriole species in winter here. 

Baltimore Oriole by Jeff Lewis
 The much rarer Bullock's is also unmistakable, but there is only one record from Mecklenburg County.
Bullock's Oriole by Jeff Lemons

Baltimore Oriole by Phil Fowler
Female Baltimores like the bird above are not as strongly patterned but can be very colorful. when dull individuals occur, then it gets interesting. Note the big difference in the intensity of the yellows and oranges in the subject bird of today's blog below.

Mystery Oriole by Jim Guyton

Mystery Oriole by Jim Guyton
This mystery oriole approaches the Bullock's in dullness of plumage and other details, but even this bird is brighter than Bullock's of the same age and gender in my view.