Mike the Mad Biologist

A New Meaning of “Human Shields”

I’m referring to moose, of course. From an interview with biologist Joel Berger in the New York Times:

Q. O.K., why did the moose go down to the road?

A. If she’s a native of the greater Yellowstone ecosystem and she’s pregnant, she may have done it because she wanted to give birth in a place where one of her main predators, the grizzly bear, rarely goes.

Grizzlies tend to avoid humans. In the part of Yellowstone that I’ve been studying this past decade, the Grand Teton National Park, grizzlies don’t go near the roads because they know that’s where the humans and cars are.

I collar and track moose as part of my wider research on prey-predator relationships. For the past 10 years, we’ve noticed that Grand Teton moose are, each year, moving about 375 feet closer to the roads when they are about to calve. We think they are doing it because they’ve figured out that the paved road is a bear-free zone where their newborns stand a better chance of survival. Up in Alaska, grizzly bears have been observed killing between 50 and 90 percent of the newborn moose population. We think that the Grand Teton moose have figured out a way to use humans as shields for their babies.

Q. Is this a new behavior for them?

A. It’s recent. Until the mid-1990s, the moose of the Yellowstone basin lived in a kind of moose paradise, without predators. The wolves had all been shot out about 70 years earlier. Grizzly bears were heavily hunted, and there were few of them. Without their traditional predators, Grand Teton moose were docile, na├»ve.

That all changed in the mid-1990s when the grizzlies rebounded because of a ban on their hunt and when wolves were reintroduced to the Yellowstone region. The first Grand Teton moose to encounter a wolf probably thought it was nothing more than a big coyote, which she didn’t fear. We reconstructed the interaction from tracks we found in the snow. From what we could see, the wolves just walked up to the moose and grabbed her 300 pound calf and ate it.

Grand Teton moose have learned a lot since then. Most of us think of moose as these dim lumbering Bullwinkles, but they figure things out. Today, if I were to play wolf calls over a loudspeaker to a herd in the park, they’d become vigilant — and they’d move away.

Q. Isn’t this just moose instinct at work?

A. No. They didn’t do it 15 years ago.

Have moose no decency? (and why isn’t it meese?)

Comments

  1. #1 Joseph Hewitt
    February 12, 2008

    You can’t afford to have decency when you are one of the most delicious animals on the planet. So it is with moose.

  2. #2 6EQUJ5
    February 12, 2008

    Years ago, mule deer came down from the foothills above and moved into Jet Propulsion Laboratory, where they have built up a herd. They are not entirely safe from cougars and coyotes, but those predators are extremely skittish about being near humans. The deer have learned to live in sight of people. They browse the nicely tended lawns, and yearly feast on the acorns of live oak and the flowers of jacaranda. The does have brought their fawns down to the mall, where they ‘hide’ in plain sight of hundreds of people, curling up and not moving, while mama keeps an eye on the little one.

    A few of them have learned to operate the turnstiles so that tall fences won’t hold them in. And they will often cross only at marked crosswalks, which they’ve seen people do.

  3. #3 Tatarize
    February 13, 2008

    How long would it take to instinctualize breeding patterns? Don’t many creatures reproduce near their own breeding ground? Couldn’t you have a slight evolution towards safer breeding grounds even sans genetic changes? I’m often amazed at how quickly populations can adapt to new situations. I could also see perhaps the deer picking up signs of the predators and as the predators move away from the humans they leave a void of predator action.

    There was a question on the Evolution 101 podcast a couple years back as to whether all the cars hitting deer could cause some evolution in the population. I’d be impressed to know what the reasons are to avoid these roads.

  4. #4 Mark P
    February 13, 2008

    Tatarize, there are probably other things at work with deer and roads. Almost every time i drive home at night I see groups of up to 10 deer feeding near the road. I suspect that the reason is that roads allow growth of the kind of edge-of-forest forage that deer prefer.

  5. #5 michael Schmidt
    February 14, 2008

    >They are not entirely safe from cougars and coyotes, but those predators are extremely skittish about being near humans.

    That’ll change. 15 years ago, when I moved to the outskirts of another Southern California suburb, the calls of coyotes were distant. Now, the coyotes are calling from 100 ft behind my house, coyote scat on my front lawn isn’t all that uncommon, and two weeks ago I saw a coyote strolling down the sidewalk at 2:30 pm on a bright sunny day. Perhaps it’s an effect of decreased habitat due to fire (I’m about 2 miles away from the fire-affected land in SD county) but it does show that coyotes aren’t all that skittish if there’s no active resistance to their infiltration.

  6. #6 Alan G
    February 16, 2008

    Regarding the moove to nearer roads, in birds of prey at least there is a tendency to pick a nest site similar to the one the new parent was raised in. If moose pick a calving ground similar in sound and smell to the one they were born in, this would generate an adaptive change even without any actual genetic changes

  7. #7 magic
    August 22, 2009

    very thanks for article