Coyotes will definitely have an affect on your deer herd. In the spring when the fawns are born. I've seen both bear and coyotes pull a fawn out of a doe and then drag or carry it off to eat it. There's not a lot a doe can do to protect herself or the fawn when giving birth.
On one of my coyote hunting tapes the hunters found 13 fawn skulls in just one coyote den.
Good luck.

critch