Is That a Marmot Under My Hood?

This large mountain rodent may pose a threat to your car

02-01-2002 // Andrew Becker

AN ODD SORT OF JUNKIE is wreaking havoc in the Mineral King area of Sequoia National Park in California. Hanging out underneath cars in the parking lot from May to August, the addicts often camp in groups of four or five. Their poison: toxic antifreeze. The hooked: yellow-bellied marmots. Fearlessly climbing into the engine blocks of vehicles, the rotund rodents chew through brake lines and radiator hoses in search of a fix of ethylene glycol--an alcohol in the antifreeze. "Some 200 marmots do this every year, damaging 20 to 40 cars," says U.S. Fish and Wildlife Service biologist Harold Werner. "It's almost like the marmots are waiting for the cars to show up when Mineral King opens."

No one knows why they do it, but Werner thinks the animals could be trying to supplement their diets--after weaning in early summer--with the crusty mineral deposits often found on engine parts.

As many a backcountry camper discovers, yellow-bellied marmots will gnaw through anything to get at stashed food or salty, sweat-stained clothes. Known as "whistle pigs" because of their shrill warning chirps and portliness, these surprisingly quick, 4- to 11-pound ground squirrels live in burrows at elevations of 6,500 feet or higher and forage in open, rocky areas from New Mexico to southwestern Canada. Tawny brown except for their yellow bellies, they grow to just over two feet long, including their bushy tails.

One of fourteen marmot species throughout the world, yellow-bellied marmots are prey for coyotes, badgers, bears and raptors. But they suffer most during winter hibernation, when they can freeze in too-shallow burrows or starve if they weren't able to store enough fat from their diet of grasses, forbs, flowering stalks and, for some, antifreeze.

Biologists first noticed marmots staking out the Mineral King parking lot in the early 1980s, shortly after the area was added to the national park. Werner suspects that marmots stayed away from the parking area before because dogs had been allowed to run unleashed. But when the area became part of the national park, leash laws were enforced, and the marmots may have started to lose their inhibitions.

Drawn to the sweet-tasting poison under car hoods, some marmots have ended up as unintentional stowaways, holding on for hundreds of miles while motorists drove as far as the Santa Monica Mountains in Southern California before discovering the uninvited passengers. But the offense doesn't happen only in Sequoia. In 1997, three juvenile male marmots were found alive and well under the hood of a disabled car that had been towed from Olympic National Park to Seattle.

Some hikers have started to take matters into their own hands, wrapping their cars in chicken wire. Many also lay radiator hoses around cars as sacrificial offerings. But so far the decoys haven't worked. And offering bowls of antifreeze is not legal--marmots aren't the only ones with a taste for the substance.

"Antifreeze has an innately sweet flavor and aroma that attracts just about anything," says Truckee, California-based wildlife veterinarian Brooks Bloomfield. Moderate doses are lethal to cats, dogs and humans. But for marmots, it appears to cause "a bit of a high," says Werner, who has been at Mineral King since 1979.

In the absence of a scientific study--which he hopes can be undertaken someday--Werner's not absolutely certain that the marmots don't crawl off and die later. But because severed brake lines can become a serious safety problem for drivers when descending a 7,000-foot mountain, park staff and volunteers keep an unofficial watch over the marmots. Werner says it appears that the same ones that they've tagged return year after year, sometimes leaving vandalized cars in their wake. He also says marmots have an amazing ability to handle toxic substances. "To tranquilize them, they need the same dose as a bear, and a bear will be down for 40 minutes while a marmot will be back up in 5," says Werner. "If you have to redrug them, it's really hard to make them unconscious again."

Dan Blumstein, a marmot researcher at the University of California at Los Angeles, says Werner's observations raise an interesting question. "It's possible that marmots drink a sublethal dose, or that they have an enzyme that allows them to drink the stuff," he says.

In the end, whether the marmots metabolize the antifreeze or not, one thing remains certain: They're hooked.


Andrew Becker writes from his home in Tahoe City, California.

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