Coyotes behaving strangely and charging at cars near beach towns in the San Francisco Bay Area could be hallucinating from ingesting "magic" mushrooms, it has been reported.

At least two of the animals appeared to be repeatedly running at cars near Stinson Beach and Bolinas, two Pacific Ocean coastal communities about 25 miles (40km) from San Francisco. The coyotes stare down passing cars, often causing drivers to stop to avoid hitting them. The animals then run at the cars, snapping and sniffing before moving off. "It's a terrifying, yet beautiful, thing to behold," a witness told the Pacific Sun.

The Marin County Humane Society has launched a probe into the bizarre behaviour. "We're trying to figure this out," said spokeswoman Lisa Bloch.

Experts quickly discounted rabies. Though the illness causes strange behaviour, it's extremely rare in the region, and infected animals die quickly. The attacks have been going on for weeks.

The coyotes could be "tripping their tails off" eating mushrooms, in the words of the Sun, a theory not discounted by animal experts. Coyotes have been photographed munching on fly agaric mushrooms (amanita muscaria) in the wild. The speckled red-capped toadstool, believed to be the mushroom Alice in Wonderland eats, has psychoactive, hallucinogenic properties.

Ingestion of the mushroom has a long history of use in the shamanistic practices of Siberia and northern Europe, as well as in India and Iran, where it was once revered as a sacred hallucinogen.

Both coyotes and domestic dogs eat mushrooms, and can suffer from "neurological excitability", seizures and even death from toxic mushrooms. Bloch has been counselling dog owners recently on how to protect their pets from poisonous mushrooms.

The charging coyotes may also have been motivated by a driver who once fed them, experts fear, and now they're chasing vehicles in a hunt for more food. The Humane Society is continuing to investigate and is asking drivers who witnesses the aggressive coyotes or experiences a challenge from one of the animals to report the incident immediately.

Coyotes were eradicated in Marin County in the 1950s because of the threat they posed to cattle. Now there are as many as 750,000 of the animals in California, including throughout Marin County.