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A bull moose meanders on a road near Big Sky, Montana. Photo by Matthew Frank.

Study Shows Moose Hit the Road to Evade Grizzlies

Why did the moose cross the road? In Wyoming, the answer may offer some surprising glimpses into how animals learn, and how humans impact the environment in sometimes unexpected ways.

Biologist Joel Berger found that pregnant moose in Grand Teton National Park tend to gather around roads, and they creep a little closer each year. Why? Because grizzlies don’t. Mama moose seem to have found that a little human touch can keep the predators away.

“Somebody once asked me, are moose smarter than monkeys?” says Berger, a biologist with the Wildlife Conservation Society. “I don’t know that they’re smarter than monkeys, but it would make sense that they’re able to figure out where they’re less likely to get whacked.”

In his study, published in the current edition of the Britain journal Biology Letters, Berger found that over the course of a decade, pregnant moose have moved about 350 feet closer to roads each year to give birth. Other adult moose don’t. The reason, Berger believes, is that although a full-grown moose makes for a mighty big meal, even for a grizzly, a calf can be a tasty morsel.

In studies in the Alaskan Yukon, grizzlies and other predators can rip through as much as 90 percent of the newborn moose, he says. But in grizzly territory in the Greater Yellowstone Ecosystem, pregnant moose have learned that bears typically stay away from roads. They’re using “humans to shield against carnivores,” he writes.

And they’re probably not alone. There’s evidence to suggest species around the world take advantage of human’s presence to seek shelter from the law of the jungle. Vervet moneys in Africa seem to hang close to humans to avoid skittish leopoards, Berger says, and there are at least anecdotal tales of axis deer in Nepal lingering around tourist lodges to escape prowling tigers.

In Colorado, biologists have known for years that elk head to private land to escape hunters.

“Elk just have a good sense of where they’re pressured and where they’re not,” says Randy Hampton, a spokesman for the Colorado Division of Wildlife. “If there is an area where hunting does not occur, the elk will hang out there. And it’s not just private land. National Parks have a sanctuary effect.”

A 2001 study found about 40 percent of elk in a portion of Colorado’s White River National Forest headed for safe zones once archery season started. An earlier study found between 70 and 100 percent sought sanctuary once they were being shot at.

It’s so pervasive, in some areas, the Division of Wildlife tells hunters they’ll have better luck on private land than public land.

“Animals think much more than we often give them credit for,” says Mary Conner, now a research assistant professor at Utah State University, who conducted the elk study.

The message of the moose study, Berger says, isn’t so much that human impacts offer great news for moose, or bad news for bears. Grizzlies are smart, he says, and not too shy. They’ll probably start following the pregnant moose to the roads soon.

The message, he says, is that although public lands may sometimes look like preserves of some pristine bygone natural world, they’re not. Even in big, wide, wild areas, humans have an impact.

“In our zest to build more buildings and roads and bike paths for people to come to wild places,” he says, “we’re actually having a subtle but very real effect on the behavior of animals. So what we think is pristine or baseline is actually not. My take is, we’re just scratching the surface in terms of understanding the subtle but very important ways we’re changing things. Roads are just one. There must be plenty of others.”

About David Frey

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2 comments

  1. Very cool picture of the moose!

  2. Actually, moose are being run out of Idaho by wolves, and crossing into Oregon which now has resident, reproducing moose numbers approaching one hundred. They are in the NE corner of the State, across the Snake River from the 7 Devils country and the wooded southern end of the Palouse. They just didn’t leave home because Erikson went to Arizona State. They moved to Oregon for the same reason the ones in Wyoming are hanging out along the road: no wolves or grizzly bears.

    I first noted this phenomena a few years back after the ban on hunting bears and cougars with dogs here in Oregon. Soon after that, coincidently, we got some sort of louse from European deer that caused the blacktail deer to lose hair. That it has not gone over the Cascades to the mule deer country is probably just due to geographical constraints on who goes where to winter off the summit. A grad student did gather a bunch of orphaned mulie fawns and another bunch of blacktail fawns, and he kept some mulies separate in one area, some blacktail separate in another, and had a third bunch of mixed fawns. He then watched to see who ended up with hair loss syndrome. All the mixed ones did, as did the separate blacktail. Not so the separate mulies. Science of a sort.

    So in winter, this hair loss deal results in some bald deer huddled up against the dryer vents of homes in town, or on the outskirts. Hanging out in open barns at night. Just looking to keep warm. Not unlike Yellowstone wolves with the mange. Just some shivering bald critters looking for a little warmth. The need to survive trumps being afraid of people. And in summer, when they least need the warmth of hair, the deer all hair up again, and the louse disappears to nobody knows where, and out it pops again come winter. And Bambi again shows up outside the dryer vent or the super efficient gas furnace exhaust.