My hawk also drops snakes... maybe he has a claw problem. I have a small lake right by the house and I find dead water moccasins in perfect condition except a few inches where they got grabbed and swooped up.
Any bird that kills moccasins are welcome in my world! Sounds like he has a talon or foot problem. Our hawks hit a branch and stick like glue and the only thing we have seen drop (my wife/kids saw it) was the neighbors cat getting dropped by an eagle.