The most damage the coyotes will do is on the fawns in the spring. I have a friend in Neb. that found a den that had several fawn skulls around it. If and when snow gets deep and crusty, that is when full grown deer will be in danger most. Even a small pack of coyotes will have enough advantage to take down a deer then.
Arounnd here, I seldom see more than 3 coyotes together, but I have called in as many as 7 at one stand!