Sunday, November 29, 2009

Melanistic Black-capped Chickadees in Aroostook Co

Presque Isle birder, Sue Pinette, recently forwarded a couple of interesting bird pictures that she'd received from her friend, Susan Chandler. Sue C. had a small dark bird visiting her yard on the northeast side of town and got a couple images of the bird when it visited her feeders.

As you know if you read the title of this post, I believe the mystery bird is an unusually dark plumaged Black-capped Chickadee. A quick summary of the pertinent characteristics is probably in order to support this identification....

First, thanks to Sue's nice, clear shots, it was easy to get a good look at the bird's plumage: the bird had an all dark head, a dark gray back, wings and tail and a slightly lighter gray underside. The eye, beak and feet were also black.

This late in November there are a few bird species in northern Maine that look somewhat similar to Sue's bird. But the apparent best-fit is probably the Dark-eyed Junco. So this species should be compared with the bird in the photos. The junco is small bird with a dark head, dark gray back and a dark eye- like the bird in the pictures. Unfortunately, the similarities end there. Juncos also have a clean white belly and white outer tail feathers and a light pink bill. None of these were visible on the bird in the photos.

Though the plumage doesn't match any local bird species, before considering more exotic bird species we should look for subtler clues to the birds identity... Judging the bird in comparison with the feeder and sunflower seeds inside, its evident the bird is a small one. Looking at the bird's shape is helpful. The bird is stocky with a blocky head and short stout bill. The second photo shows the bird with a single seed and apparently ready to fly from the feeder.

All of these point to one of the commoner species around feeders in northern Maine these days: the Black-capped Chickadee. I'm sure if we could watch the bird flitting back and forth from the feeder to the woods and hear it vocalize we'd be able confirm this ID.

It appears Sue's mystery bird is an unusually plumaged chickadee possessing an abundance of the dark pigment melanin. This extra pigment causes areas that are normally light or white to appear black or dark gray. These melanistic birds are substantially rarer than the opposite form of aberrant albinism. Here is a look at a normal plumaged Black-capped Chickadee taken at my Woodland feeders for comparison with these dark ones.

Even though I tried to explain how I could come to the identification of Sue's bird above, in truth, I jumped to this conclusion fairly quickly. This wasn't because of any great insights on my part, but actually because there have been several dark chickadees reported in the northeastern parts of Presque Isle in the past ten years or so. I've sorted my way through this ID before!

Roberta Griffiths first reported an all dark chickadee at her feeder back in 2003. The bird stayed at her yard most of that winter and she was able to get a video of the bird and in the recording one can hear it give the classic Chick-a-dee-dee call of the Black-capped.

More recently, Roberta also brought me the photo of a dark chickadee seen here taken at a feeder on the Parkhurst Siding Road in Presque Isle. The picture was taken in January 2008. While not quite as dark as Sue's bird and certainly not all black, the bird also has an all dark head like the others.

Here is a cropped version of the same picture:

Though the observations of these melanistic chickadees were made in locations that are only a couple miles apart in the north eastern side of town, the span of time (7 years) and the apparent difference in relative degree of pigmentation would seem to indicate that there is a small population of melanistic chickadees in Presque Isle. I'm not sure but I don't think this has been reported before.

Though extremely rare, melanism in chickadees has been reported before. James Tanner (the famed Cornell ornithologist who filmed Ivory-billed Woodpeckers back in the 30's) found one in up state New York in 1933. His paper on the discovery can be found online here:

Alfred Gross, a Bowdoin College ornithology professor, wrote about the rarity of melanistic birds in an article for the Journal of Field Ornithology in 1965

Good stuff indeed


Rick said...

Bizarre! And wonderful. Thanks for putting these up.

Sarah said...

Chickadees are my favorites among the little birds...and these dark beauties are just lovely! Thanks for the photos and the informative narrative.