Isn’t he beautiful? He was caught in the hills in Marin County, not all that far from me, and kept in captivity until he died in 1931.
You might think he’s purely colorless at first glance, but he isn’t. He’s more blue-silver than white, an incredible color to come shining out of a drawer of junco specimens when you’ve just spent the last few weeks measuring the same brown-and-black birds over and over. When you look close you find that hidden in those pale feathers are the whispers of normal junco coloration.
The silver bird has a dark hood—it’s very light, but it’s there (compare with the normal bird on the right):
Both the normal and the silver junco have white bellies:
But the white underparts of normal juncos are only white on the outside. If you brush the feathers aside so that you can see the whole feather, you find that the feathers are dark at the base and white at the tip:
The silver junco shows the same pattern, just much paler.
Strangest, to me, is that if I wanted to I could score the amount of white on the silver junco’s tail. Now I don’t mean that I could say “100% white!”—I mean that I could see how much white he would have displayed if he had not had his color abnormality. Where a normal junco has black tailfeathers and white tailfeathers, the silver junco has very light grey tailfeathers and white tailfeathers; the difference is perceptible.
A junco shot in Pennsylvania in 1895 was described in very similar terms, right down to the “downy basal part of the ventral feathers” being pigmented (Caspari 1944). A junco seen feeding with a junco flock in British Columbia in winter 2008—and not shot; these are kinder times—looks from the photo to also be quite similar, including a very, very light grey hood. From observations he appeared to be in the middle of the junco flock dominance hierarchy, so clearly juncos not only recognize a silver junco as a junco, but don’t necessarily perceive him to be inferior (Cartwright & Cartwright 2008).
It’s too bad he was last seen in March 2008. I’d give a lot to know if he was able to attract a mate, and to see what his chicks looked like!
I’ll have to content myself with the 1931 specimen. He’s beautiful. It’s just too bad that he doesn’t do more…
Cartwright C, Cartwright K. 2008. Albino Dark-eyed Junco at Canal Flats, British Columbia. Wildlife Afield 5(1):42-43.
Caspari E. 1944. A color abnormality in the Slate-colored Junco. The Auk 61(4):576-580.
Interesting discussion. I’m fascinated with plumage aberrations, and Juncos, so this post was a good find for me. Check out this paper on plumage aberrations:
Click to access vanGrouwHein2006_NotEveryWhiteBirdIsAnAlbinoSenseAndNonsenseAboutColourAberrationsInBirds.pdf
Great stuff, and great write up!
Thanks for the great article! What a fantastic collection of photos; I’m also fascinated with plumage aberrations. Where is the article from? I don’t see a journal or magazine title associated with it.
The article is from the January 2013 issue of British Birds. Glad you like it!