The depletion of the Earth's ozone layer by aerosols has been causing increased exposure to UV radiation at high altitudes. Scientists observe that animals over 5,000 feet in altitude become highly aggressive. One small-town sheriff barely escapes getting mauled to death by rats. The government orders the evacuation and quarantine of all settlements above that altitude.
In the midst of this, a group of tourists in Northern California set off on a hike through the wilderness, led by Native American guide Santee (Michael Ansara). With no way of communicating with the outside world, they are ignorant of the strange animal activity and are baffled when a mountain lion attacks their camp. They shrug off the incident and continue the hike, as the woodland creatures eye them menacingly. Later, they are beset by hawks, and a woman falls to her death as a result. They abandon the hike upon finding that their helicopter-dropped food cache has been raided by animals.
Hiker Paul Jenson (Nielsen), a smug and confrontational executive, abandons Santee and takes four of the hikers with him: a mother and her boy and two young lovers. He hopes to find help at a Ranger station. The guide takes a less risky route down the mountain. The hikers are not immune to the high-altitude aggression anomaly, and tensions begin to run high. The especially aggressive Jenson finally boils over; he kills one of his charges and attempts to rape his girlfriend. A grizzly bear approaches, however, and he dies trying to wrestle it. The boy, his mother, and an older hiker manage to find refuge inside an abandoned helicopter.
One hiker strays, and picks up a little girl who was abandoned when the government quarantined her town. He tries to drive her to safety, but is slaughtered by vicious dogs and venomous snakes, leaving the girl alone in the relative safety of a junk car. The others manage to get to a town below 5,000 feet, but find it deserted. A pack of German shepherds kills two of them and Santee leads his surviving charges onto a raft in a nearby river. They are rescued the next day as they float downriver to a Ranger station.
The next day, U.S. Army soldiers in hazmat gear arrive to secure the towns. By then, almost all the animals that went mad have been killed by the same solar radiation that drove them mad in the first place. The little girl and the survivors in the chopper are rescued by the army. At the end of the film, a surviving hawk lunges at the screen just before the credits roll.Christopher George ... Steve Buckner
Leslie Nielsen ... Paul Jenson
Lynda Day George ... Terry Marsh
Richard Jaeckel ... Prof. Taylor MacGregor
Michael Ansara ... Daniel Santee
Ruth Roman ... Mrs. Shirley Goodwyn
Jon Cedar ... Frank Young
Paul Mantee ... Roy Moore
Walter Barnes ... Ranger Tucker
Andrew Stevens ... Bob Denning
Susan Backlinie ... Mandy Young
The budget of the production was $1.2 million. Shooting took place at Long Barn, California, on Todd-AO 35 film. The cast recalled having a good time.
Animals for the film were trained by Monty Cox, veteran of such productions as Apocalypse Now and The Incredible Hulk, who partnered with cast member Susan Backlinie. Backlinie also doubled for Lynda Day George. The grizzly bear is portrayed by the mother of Bart the Bear and had previously appeared in Grizzly. Leslie Nielsen recalls being very impressed by the animal.
Day of the Animals was released in U.S. theaters on May 13, 1977. A novelization, written by Donald Porter, accompanied its publication.
The film was released on VHS in pan-and-scan format. Media Blasters released a DVD print on April 25, 2006, under its "Shriek Show" imprint, featuring interviews with actors Jon Cedar and Paul Mantee integrated into a featurette. Scorpion Releasing published a Blu-Ray print and another DVD version in November 2013. The Blu-Ray and new DVD feature extended versions of the Media Blasters interviews, a sound track isolating Schifrin's score and the original TV spot. Katarina Waters hosts an introductory "Katarina's Nightmare Theater" segment.
On March 24, 2017, Rifftrax released a VOD of the film with comedy commentary by Michael J. Nelson, Kevin Murphy, and Bill Corbett.
Day of the Animals was mostly mocked by critics for its poor special effects, goofy premise, banal execution (derivative of The Birds) and on-the-nose environmental themes. Later reviews have noted that Leslie Nielsen's ruthless character is shocking for a modern audience raised on his work in comedy. Writer William W. Norton was himself disappointed in the film. Modest praise was issued by The Hollywood Reporter.
Some critics nevertheless recommended the film to fans of natural horror and disaster films of the 1970s. AllMovie compared it to Kingdom of the Spiders and Frogs Those who saw the film at a young age have formed a cult following of sorts.