Juncos are a very common bird, but they also represent one of the great ornithological puzzles. Depending on who you talk to, there are between three and twelve species. The number of species depends on whether you think the confusing color patterns represent color and song variations on one species or separate species. As Birds of North America puts it,
The phylogenetic relationships of all junco taxa clearly involve more complex questions than can be answered by presently available evidence.
That’s something of an understatement. A few photos may illustrate the challenges.
If you live in Alaska, this is the Junco you see most often. The whole back and chest is dark gray, with a sharply defined white belly. Dark-eyed and pale, pinkish-billed, it shows white outer tail feathers in flight.
But this is a Dark-eyed Junco, too, the “Oregon” variety, despite the pink-orange wash on the sides (giving the variety its other common name, “Pink-sided Junco”) and the darker, grayish-pink bill. The slate gray is merely a “hood.”
You guessed it; this is a Dark-eyed Junco, too, despite the rusty back, mottled gray chest and belly and black-tipped bill. There are at least two other North American color variations that WC hasn’t seen or photographed.
Most bird biologists – but far from all – recognize a second distinct species of Junco in North America.
The other is the Yellow-eyed Junco. With that electric yellow eye and bi-colored bill, it looks like a cross between a Gray-headed variety and Costa Rica’s Volcano Junco.
That’s right, there are Juncos elsewhere in the New World than North America. Happily, this species hasn’t been seen in the United States, although its range in Central America isn’t fully known.
You can imagine how pleased we were when a entirely different color variation, a leucistic Dark-eyed Junco turned up in our Boise backyard.
Leucism is the partial absence of melanin pigment in an animal including a bird. That contrasts with albinism, the total absence of melanin. In the case of this little Junco, WC thinks it resulted in a very handsome bird.
Juncos are sexually dimorphic, too; the females are generally paler and more washed-out versions of the males. Oh, and the kids are different colored, too.
It’s all another set of reasons WC loves birding.