El Dia De Los Animales (1977)

Steve Buckner (Christopher George) takes a group of hikers up to the mountains where they will begin a days-long nature hike against the advice of the local Ranger Chico Tucker (Walter Barnes), who had warned Steve that there had been all kinds of accidents lately and maybe this hike was not a good idea, but Steve refuses to call it off. Through radio and TV broadcasts it is eventually revealed that, due to the depletion of Earth's ozone layer and solar radiation being increased on Earth as a result of this, all of the animals in the world that are living above the altitude of 5,000 feet are showing signs of aggressive psychosis. The hikers soon realize that they have to survive the animals' attacks on them and make their way to safety, both before the effects of exposure to solar radiation turn the hikers themselves psychotic and before they start to turn on each other.