On Mar 12, 2011, at 7:08 PM, Casacummins wrote:

> On Wednesday, March I was driving on Highway 104, North of the Hood Canal Bridge at about 3:00 pm when a larger-than-usual coyote crossed the road about 100 yards ahead, headed Southeast. He was rangy and tall, but much darker colored than the coyotes I?ve seen before. The most striking feature however was the large, snow-white tip of the tail, The white tail is what made me notice, and for a moment I thought I had seen a fox. As I passed, he paused on the road embankment and looked toward the highway. Dark grayish-brown and the facial features of a coyote ? somewhat thin face and long muzzle, but somewhat large. Then it was into the forest and gone. Has anyone seen a color phase like this one on a coyote, or could it have been a coyote/dog cross?

Nice observation.

There are melanistic coyotes out there. Including those with white tipped tails. Like this one (**for the sensitive**: don't look at other photos in that collection ... a lot of them are coyote hunter photos).

http://media.photobucket.com/image/black%20coyote/jaylangston/BlackCoyote2small.jpg

Did it look like the one you saw? It does look more "rangy" and "dog-like" than my mental version of a "normal" coyote but I think that's more in my mind than in reality: it's colliding with mental images of black dogs.

The white tip is interesting. Non-melanistic coyotes typically have a black tip Does one ever see white tips in non-melanistic coyotes? Yes but perhaps it isn't as obvious as in the black coyote.

http://www.flickr.com/photos/kjdrill/1451180519/
http://www.desertusa.com/june96/du_cycot.html

Is it a cross with a domestic dog?

Probably not recently but perhaps at some time in the past it was. Or may be not. The technical story is interesting. There is some argument that they get their black color from cross breeding with dogs rather than a straight mutation of MC1R gene.

The mechanism in coyotes (and wolves) appears to have a different mechanism: a specific mutation (at the K locus) on another gene CBD103 but it acts on the same MC1R receptor. Most of the time coyotes are (two tone -- "sable" in dog speak) phaeomelanin colored (tan/brown) but if they get a MC1R receptor turned on they color their pelage with eumelanin and appear (single tone) black.

The papers linked below claim the melanistic K locus mutation in North American wolves derives from past hybridization with domestic dogs. It also has high frequency in forested habitats and looks like it underwent positive selection for wolves and coyotes in "dark" environments.

http://www.sciencemag.org/content/323/5919/1339.abstract
http://www.canislupus.it/public/AndersonScienceExpress.pdf

Or the quick version in a blog

http://evolutionarynovelty.blogspot.com/2009/06/whos-afraid-of-big-black-wolf.html

As you can see from the comments there are some discussions of where this K locus change came from.

OK, it's not birds but another example of how MC1R and animal coloration work across a wide range of vertebrates.
--
Kevin Purcell (Capitol Hill, Seattle, WA)
kevinpurcell at pobox.com
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