I've used Caribou for tails, and/or wings, where deer or elk has been called for.
"Just cuz I had it", and for no other, real, reason really. Although the boo I have is very light in color so it does make a nice "sight visual" type fly when used as a wing.
Unfortunately, at least MINE anyway, is not as hardy as deer hair and not even close to as durable as elk. So, I haven't used it all that often.
Saint Paul-"The Highly Confused"
You cannot do a kindness too soon, for you never know how soon it will be too late.
-- Ralph Waldo Emerson