High Desert Kill (1989) Harry Falk

Like every year, Jim, Ray, Brad and Paul leave the town for a week to go hunting in the woods. But this year everything is different: There’s not a single animal to be found, the whole forest has fallen quiet. Two female campers they meet have mysteriously disappeared the next day, leaving their whole equipment behind. And then they start to behave weird themselves… An alien power is using them for cruel psychological experiments.