Vucetich Discusses Long-Running Predator-Prey Study
MELISSA BLOCK, HOST:
Go up, up, up in Minnesota, up to the boundary waters with Canada. Then if the weather clears, hop onto a tiny research plane and fly 15 miles out across the ice of Lake Superior to the wilderness island of Isle Royale. That's where wildlife ecologist John Vucetich is now and where he's been going every winter for the last 12 years to study wolves and moose. He joins us from the researchers' bunkhouse on Isle Royale. John Vucetich, welcome to the program.
DR. JOHN VUCETICH: Yeah. Thank you.
BLOCK: You're involved - this is the longest running study I've read of any predator-prey system in the world, been going on for more than 50 consecutive years. Why are you studying wolves and moose there on Isle Royale? What's the goal?
VUCETICH: The goal is to basically understand how it is that wolf populations affect populations of their prey. In this case, it's moose and the reason we're interested in that is because wolves and humans sometimes conflict with one another. So this study, a lot of it is to understand how, in fact, it is that wolves affect their prey.
BLOCK: And how are you doing this? How do you track these populations on the island?
VUCETICH: Well, every year, we come out for about seven weeks in the wintertime and we'll fly every single day during this period that the weather will allow us to do so. And a couple of these wolves are radio-collared, so we can find their signals that way.
And much of the time, we're just flying over the island looking for tracks in the snow. And we find the tracks in the snow of these wolves and we follow those tracks until we find the wolves. And then, also, when we're following those tracks, next we can see where it is that they've killed the moose and - because that makes quite a scene on the snow, blood and hair and all that kind of thing. And when we know how often they're killing the moose, then that's a part of how we can figure out their impact.
BLOCK: Well, what have you been finding there in recent years in the work that you're doing?
VUCETICH: Yeah. Well, the wolf population has gone to really quite low numbers. Last year, when we counted them, there were 16 wolves. But maybe more surprisingly, the 16 wolves - only two were females. And if those two females go - you know, if they die before giving birth to more females, then that would be the end of the population. So what we're really keen to pay attention to now is to look for signs of mating.
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BLOCK: I almost hate to ask this, but if you're looking for signs of mating, is it pretty obvious what you're looking for, what those signs would be?
VUCETICH: It is, yeah. The males and females are very hierarchical. There's an alpha female and she's dominant over all the other females and similar for the males. That dominance behavior is real characteristic when both sexes are present.
And also, wolves - the physical appearance of them mating looks a lot like when dogs mate. So, we frequently see that. And it may sound peculiar, but it leaves a distinctive set of tracks in the snow and so we can tell from that, as well.
BLOCK: Wow. Wait, wait. You can see a distinctive set of tracks from an airplane that would tell you that wolves have been mating on the ground?
VUCETICH: Yeah. Well, what they do is, when a male and female wolf mate, we say that they're tied together. And when they're connected like that, they kind of wander around the snow a little bit. Not very far, but just wander around.
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VUCETICH: But, you know, you got eight legs instead of four, all connected, and they don't have a normal gait.
BLOCK: Well, I guess if you've been doing this as long as you have, you would know what that looks like, even without the wolves there.
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VUCETICH: Yeah, yeah.
BLOCK: What do you think accounts for the fact that the population has declined so much?
VUCETICH: Well, the wolf population is low right now, mainly because the moose are so low. There's a special kind of tick that bothers only the moose, and this tick has been quite abundant in recent years. And this tick is also tied to climate change. This tick does much better in warmer weathers and we've had increasingly warm weathers in this last decade.
And then, finally, moose are creatures of the North Country. They do best when it's cold. And these warm weathers are just tough for them. So, climate change is certainly a big, big suspect here.
BLOCK: Well, John Vucetich, enjoy the rest of your time there on Isle Royale this winter. Thanks for talking to us.
VUCETICH: You're welcome. It was great fun to share.
BLOCK: That's wildlife ecologist, John Vucetich, talking with us from Isle Royale, Michigan in Lake Superior. His blog posts are appearing on the New York Times website.
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