Fishing with wolves: New exhibit explores what the predators eat in summer

A new exhibit at the International Wolf Center in Ely explores how wolves survive during the summer months, a tougher time to bring down their usual prey.

Titled “Starvation, Adaptation and Survival — Insights from the Voyageurs Wolf Project,” the exhibit showcases research from the University of Minnesota.

In summer, researchers say wolves must expend extra effort to feed themselves and their pups.

Tom Gable, the lead researcher, spoke to MPR News about the exhibit and his findings.

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The interview is edited for clarity and brevity.

Why is it difficult for wolves to find food in the summer?

Gable: Their prey are generally in pretty good condition, particularly deer, which are wolves’ primary prey in northern Minnesota. During the summertime, deer have abundant vegetation, which means that they’re in good physical condition. There’s not deep snow or other conditions that impede deer’s ability to escape wolf predation. Certainly deer fawns are born in the early part of the summer but those fawns quickly grow up and become very mobile and able to evade wolves.

One of those other food sources in our area are beavers. But even beavers are very difficult for wolves to catch and kill during the summer because beavers don’t spend a lot of time on land during the summer period. There’s a lot of abundant aquatic vegetation in beaver ponds, which likely limits how much the beavers have to go on land to cut trees to get food.

What happens is a wolf’s main prey — beavers and deer fawns during the summer — are available in sort of little pulses.

At the same time, what’s happening is pups, born in the spring, continue to get bigger and bigger, meaning they need more food and more calories. Naturally, there’s this bottleneck towards the end of late summer, early fall, when [they] simply are not able to get enough food to feed themselves and to feed their pups.

What will people learn at this new exhibit?

My hope is that folks get an appreciation for the adaptability of wolves who figured out how to take advantage of food sources like fish and berries. And so the hope of the exhibit is to present a realistic perspective of wolves. Oftentimes, we see wolves portrayed as wonderful social creatures and the cute, cuddly moments, or we see some of the unpleasant ones.

We’ll also have video footage from our trail cameras in the exhibit. Those videos allow people to see the wolves themselves going about their day-to-day lives. It shows wolves that are killing beavers, that are eating fish, that are foraging on berries. It also shows wolves and their pups at the dens and then it also shows what happens when wolves don’t find enough food.

We see pups that are starving to death, and then pups that eventually don’t make it. So there’s a combination of all sorts of media capturing different parts of our research.

How many trail cameras do you do you have?

Right now, we have about 350 trail cameras.

We’ve recently purchased more because we realized that trail cameras provide an invaluable source of information. Trail cameras are able to see and observe in a way that we can’t in person. We’ve just realized that a lot of big insights have come through trail cams, and a lot of our understanding of wolves in the area do depend on having trail cameras having eyes in the woods.

Are there scientific things you’ve learned from these cameras?

We’ve learned a lot about [behaviors] such as wolves catching fish, or eating berries. A good chunk of that has come from trail camera videos, where we’ve been able to document these behaviors that would never have been observed before. And then we put out these cameras in combination with information from the GPS collars, because the newer wolves are traveling.

We’ve had a wolf, several wolves actually, in our area catching fish over the past couple days. We got this female wolf that was at this creek, waiting in ambush, great video footage of her just sitting there for 20 minutes just waiting for fish to come up.

We use trail cameras for all of our populations and pack size estimates in the wintertime.

Traditionally, biologists would get up in airplanes and fly around looking for collared wolves with an antenna. That is very expensive, has some safety risks, and also only gives you one observation, you’ve got to fly every time you want an observation. So instead of using that kind of approach, we just bought a bunch of cameras, and we leave our cameras in the woods all winter.

What does it look like when a wolf is fishing?

The wolf comes to a spot in a river that’s generally quite shallow. They’re waiting in the pitch black of night because that’s when the fish they are going after, white suckers, are generally running in these rivers and coming into shallow areas to spawn.

You can just watch her ears continuously monitoring for sounds, constantly flickering and twitching, listening for any sound to indicate that fish are coming upstream. Once she finds or detects a fish, you can see the wolf just immediately snap into go mode.

It’s pretty cool to see.

How much does the white sucker help the wolf?

White suckers, typically running in the spring, swim shallow areas making them very vulnerable and easy for wolves to catch and kill. We have not documented wolves eating really any other fish at this point.

Now in terms of how many calories a wolf gets from a sucker, we don’t know that, it’s not something we’ve ever tried to measure, but it is certainly something we are curious about.

My guess is they probably actually get quite a few calories while the suckers are running. So for a couple of weeks fish might be a really big food source, but then outside of that couple of weeks of the year, might not be that significant.

And not just the female but also her pups, right?

Yep. Also her pups. It’s a food source that’s allowing her to keep those pups alive because spawning fish are full of fat and other nutrients. If they can catch fish regularly, they’re probably doing pretty well at that time.