Love 'em! I was going to try and get out to find some coyote pups to take pictures of yesterday. Didn't happen though. Daughter talked me into a motorcycle ride instead...
I would guess about.. 30-40 feet away with a 500mm on a full frame body, I am planning on getting a 2.0x and a 7D body to go with my 5d MKII ... I could stand out there with those little guys for HOURS and snap pics so cute!