A coyote doesn`t get to looking that good by eating mice and picking bones.
He knows what to do, and how to do it, on a regular basis. He is teaching others how to do it and what to do, and coyotes learn fast. He himself was taught well, as OBVIOUSLY his days are not spent in hiding with an empty belly.
He will go about thirty five pounds, and if he were the "old school" coyote a full grown deer would see him as not much of a threat. The problem is the "new school" coyotes have learned that a couple more thirty five pound hunting partners put them over 100 lbs combined...and now they ARE indeed a threat. I used to hear biologists say coyotes don`t hunt as a pack, but I don`t hear that anymore.
Nightime hunting (if it is legal) and traps. Get out after him, or them, as I`m sure he is not alone. (They do not look that good when they live alone.) In case your interested, I have seen coyotes pick undigested corn out of cow manure. I watched them through binoculars because I could not shoot in the direction he (they) were, and walked up afterwards to see what they were doing. I have no doubt, you will start finding scat containing your corn meant for the deer.
They are a supreme challenge with whatever method you use to kill them.