ALONG THE MOOSE RIVER — The violence happened in a tall-grass meadow, just off the riverbank, and most anyone else who might wander by here would have missed it entirely.

But dropping down on their knees, Tom Gable and Austin Homkes saw more than just depressions in the grass. They didn’t miss the tiny specs of beaver hair, the wolf scat with more beaver parts, a piece of pelvis bone from a beaver.

“Tom, we’ve got stomach contents here,’’ Homkes hollered. “This is definitely a kill site. There was a struggle and a kill here.”

Gable and Homkes found more evidence of how the beaver, apparently unsuspecting, waddled up from the river onto shore where it appears — and this is pretty much new to science — the wolf was waiting for it.

“It was always assumed that wolves attacked their prey by chasing it down, all of it… But what we are seeing in some of these GPS clusters is that some of these wolves go to places where they expect beaver to show up. And sometimes the beaver shows up,’’ Gable said. “Wolves are waiting out their prey and ambushing it.”

The project has documented 450 attempts by wolves to ambush beaver and 189 successful kills.

Chalk up another first for the Voyageurs Wolf Project, an ongoing effort to learn more about wolves and their prey in Minnesota's only national park. It started small in 2012 as a project of the National Park Service, with Gable as a graduate student helper and six GPS collars that gave wolf locations every 12 hours. In 2015 Gable came back, by then a University of Minnesota PhD student ready to dive into the effort with higher-tech, longer-life collars that pinpoint wolf locations every 20 minutes; 72 times a day for months on end. Since 2012 researchers have trapped and collared 75 wolves from a dozen packs, then investigated thousands of GPS points where the animals roam, stop, eat and sleep. Eleven wolves have working collars this summer.

The researchers know the wolf that killed the beaver along the river is a female, previously trapped, collared and ear-tagged as No. V-076. She has five pups this year, the alpha female of what they have named the Wiyapka Lake Pack that has just three adult wolves. She is a good hunter-killer.

Deeper in the woods, about a half-mile from the beaver kill site and just off an ATV trail on the national park boundary, the researchers honed-in on another GPS cluster from V-076 where they collected tufts of fawn hair, bone chips and deer stomach contents. Small, slow-moving fawns, the project has found, are another critical food source for wolves in midsummer when fast-growing pups need lots of meat but aren’t big enough to help hunt. (It’s too soon to draw conclusions but an average seems to be about one beaver and one fawn per adult wolf every 7-10 days in July and early August; a fawn every 3-4 days in June.)

Summer secrets unveiled

In just five field seasons the Voyageurs Wolf Project has uncovered a treasure trove of new information on the secret summer lives of Northwoods wolves, what had been a mostly blank slate. Nearly everything we knew about northern Minnesota wolves before came from winter studies. Yet summer, when pups are born and raised and rebuild high-mortality wolf populations, is a critical time for the species.

There are about 60-80 wolves in 10 or so packs in and around the park now with eight researchers in the wolf project following them around. The project was the first to document that Northwoods wolves catch and eat freshwater fish and the first to substantially document that some wolves spend weeks on end in blueberry patches, during good berry years, with scat samples showing berries were sometimes all they ate. (Project researchers have collected and analyzed thousands of wolf scat samples.)

The project has documented that wolves — famously known as a pack animals in winter — are mostly solitary hunters in summer, meeting only occasionally at rendezvous sites. They were the first to capture video of a female wolf rescuing her pups from a flooding den; of Great Lakes region wolf pups playing, sparring and howling; of wolves hunting in summer, almost always after small prey like beaver and fawns (as opposed to winter pack hunting for adult deer and moose.)

All of this action is happening near thousands of anglers and houseboat visitors in the park, yet it's almost always out of sight.

And now the project is documenting the relationship between wolves and beaver, which are apparently a much more common and important food source for wolves than previously believed — especially in Voyageurs, one of the most beaver-rich areas in the nation.

“Everyone assumed wolves ate beaver in the summer. But no one knew how much, how often or how they do it. The same goes for fawns. Fawns make up a big part of their summer diet, but no one really knew how big,’’ said Gable, 27 and the project leader. “That’s what we’re trying to do.”

The wolf project has underscored that wolf diets are highly variable, that the animals can switch back from stalking and chasing to ambushing as needed and that they are as much omnivore as carnivore. Wolves will take advantage of what’s the easiest, most available food source in their territory. So far in the study beaver make up between 10 and 42 percent of the summer diet of Voyageurs area wolves. Yet in five field seasons and 600 kill sites they have found only one adult moose killed by wolves. (The project also has documented that wolves also feed often on deer hunter’s gut piles and bear hunter’s bait piles and that wolves regularly use ATV and snowmobile trails to find their prey.)

Wolves in the project have even captured and eaten three trumpeter swans, something never before documented.

The Voyageurs-area woods in summer can be a nearly impenetrable mass of trees, shrubs and plants. Add temperatures in the mid-80s, humidity levels nearly as high and swarms of biting flies and mosquitoes so thick that they trigger motion-activated trail cameras to turn on, and it’s easy to see why most wolf research is done in winter.

Famed Minnesota wolf researcher Dave Mech in 2010 published a scientific paper declaring that a summer wolf research was indeed very difficult. In one effort Mech’s team found only one beaver kill site all summer. Now, the Voyageurs Wolf Project has documented hundreds — a total of 600 summertime kill sites, mostly beavers and fawns.

“We’re out mostly from April through October… seven months that had been just an empty box for data,’’ Gable said.

In the past, even when they did try to go out in summer to find wolf kills, researchers really weren’t sure what they were looking for. The place where a wolf kills and eats a beaver, or a fawn deer, isn’t obvious. There are few bones, little blood splatter and almost no obvious evidence left behind (a winter kill leaves tracks and blood on snow.) But experienced crime scene investigators like Gable and Homkes have figured out how to find tiny shards of summer evidence.

“They eat almost everything. There isn’t much left to find,’’ said Homkes, 27 the project’s field leader. He’s a National Park Service technician and a graduate student at Northern Michigan University. “But we’ve learned what to look for.”

Very social media

Over the long-run, all those GPS reports don't just show where the individual wolf roams, but also precise pack territories. A color-coded image of the travels of the eight Voyageurs-area wolf packs over time went viral on social media because it so perfectly defines how the packs avoid each other.

The concise territory boundaries were something most wolf scientists knew well but which had never been described well to the public.

“Most of this wouldn't have been possible without our GPS collars. We’re getting their exact locations every 20 minutes. And that shows us where they stop to kill and to eat and to den… It’s giving us more precise information of where we need to look: for kill sites and evidence, Gable said. “We can go in and confirm things that now that you couldn’t do before.”

In addition to their kill-site research, the wolf project scientists also have deployed 50 trail cameras in high traffic areas, half video and half still image. The images captured have been both a scientific and public relations jackpot, including that now-famous video of a wolf catching and eating fish. (It turns out that, for at least one Voyageurs wolf pack, the Bowman Lake Pack, those spawning fish are a brief but important food source each spring.)

With higher quality and less expensive cameras now on the market, scientists worldwide are using trail cameras as another tool for their fieldwork. But Gable and Homkes also are using them to inform the public about what they are doing and why it’s important. (From just one camera over a few weeks — placed on a portage between Namakan and Sand Point lakes — researchers collected images of multiple bears, three wolves, fox, flying squirrels, red squirrels, a pine marten flushing grouse, a bobcat, raccoons, bugs and some cussing canoeists portaging through mosquitoes and mud. Eventually, a bear bumped the camera so it only captured video of treetops and sky.)

For anyone into wildlife, it’s just plain cool stuff. But it's also big-time stuff. Since the News Tribune first wrote about the wolf project's remarkable findings last December, National Geographic has featured the project, as has the PBS show Nature and National Public Radio.

So far the wolf project has produced a dozen peer-reviewed, published scientific research papers, the gold standard for research (including wolves ambushing beavers and eating fish.) More are in the works. Their contributions are breaking new ground in summer wolf research. But their efforts on Facebook and Instagram and through traditional media like newspapers and television have brought the researchers and their subjects an incredibly broad audience. The Voyageurs Wolf Project has a fan base of 22,000 Facebook followers.

Nearly every week Gable and Homkes pore over video and photos and other data to update their social media sites. Neither Gable nor Homkes seek out reporters. But they are willing and happy to talk when they call.

“Your ability to reach people is directly related to the quality of your content,’’ Gable said. “Outreach requires effort. You have to put the same effort into the outreach that you do into science... It's rewarding to see people react to your work, to have them be interested in what we do."

Great video, with audio and explanations that people understand, has been key, Homkes said. "People like the process of science. They like to see how we are doing it, even more than the results."

“You could study wolves in Minnesota for years, be in the woods every day, and never see a wolf in the woods... It’s not like Yellowstone where you can see for miles off over a valley,’’ Gable added. “The cameras have enabled us to see things no one has ever seen before, at least not in Minnesota, not in the summer.”

Both Michigan natives, Homkes and Gable are hoping to stay in Minnesota for a long time. Their goal is to see the Voyageurs project become a permanent effort, much like the Isle Royale wolf-moose project now 60-years running.

“This is the one national park in the lower 48 states that never lost its wolf population,’’ Gable said. “There should be a long-term wolf project going here. The real value in this data is over the long-term.”

The Voyageurs Wolf Project is a joint effort of the National Park Service, overseen by Voyageurs Park wildlife scientist Steve Windels, and the University of Minnesota where Prof. Joseph Bump is the project head. It’s funded by the Minnesota Environment and Natural Resources Trust Fund that’s stocked by the state’s lottery profits.

Voyageurs National Park is relatively small at 227,000 acres on the Minnesota-Ontario border, much of which is comprised of large lakes including Kabetogama, Namakan, Sand Point and Rainy. It's Minnesota's only national park, much of which is accessible only by water. Unlike the nearby Boundary Waters Canoe Area Wilderness, Voyageurs is open to motorized boat and snowmobile traffic in many areas.

If you go:

The Secret Lives of Wolves in the Northwoods

Wolf researchers report on their findings so far in the ongoing Voyageurs Wolf Project.

Hosted by Voyageurs National Park Association and Voyageurs Wolf Project

Monday, 7 to 8 p.m.

Kabetogama Town Hall, off U.S. Highway 53 at 9707 Gamma Road, Kabetogama.

Free and open to the public.

Big trees, too

On their way to work every day — either driving back roads, hiking through the woods or boating on the water’s of big Voyageurs National Park lakes — wildlife researchers Tom Gable and Austin Homkes see a lot of trees, including doing some really big ones.

Occasionally they stop and measure them. And over the past few years they have found some of the oldest, largest trees in Minnesota.

While wolves and beaver are their main research effort, the duo has found the largest jack pine alive in the United States, the national champion of the species, on the shore of Namakan Lake.

They also have confirmed the new state champion red pine and the state champion black spruce (visible from the Ash River Trail highway.)

“It’s just something we do,’’ Gable said. “It’s kind of fun.”

Not so big wolves

Ask some Northlanders who have seen wolves up close and they often describe a big, burly animal, much bigger than most dogs, weighing 100 pounds or more. Ask them how many wolves they saw run by their deer stand one evening and they might say a dozen or more.

But in years of research and dozens of trapped animals, and hundreds of wolves captured on camera, researchers in the Voyageurs Wolf Project have never seen an animal top 100 pounds. Not once. And the average pack size is only about 5-7 animals, a fact verified by many other wolf studies as well.

In reality, northern Minnesota wolves might be taller and lankier than your average Labrador retriever, but they aren’t any heavier.

“We keep hearing about all these giant wolves, 100 or 120 pounds, that people say they shot when there was a season (in Minnesota) and we have to shake our heads,’’ Austin Homkes said. “Our average female is about 57 pounds, the average male about 69 pounds.”