A flourishing beaver population on the banks of the Spokane River, stretching east from the 100-acre park in the city’s downtown to the shores behind Gonzaga University at least, is being blamed for gashes in the trunks of shoreline trees.

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Gnawing nocturnal visitors to Spokane’s Riverfront Park had officials scrambling to save towering cottonwoods from a watery grave this winter.

A flourishing beaver population along the banks of the Spokane River, stretching east from the 100-acre park in the city’s downtown to the shores behind Gonzaga University at least, is being blamed for gashes in the trunks of shoreline trees. The targets are not only those in the willow and cedar families that are staples of the beaver’s diet, but also pine and hawthorn trees that don’t have the type of bark the creatures prefer.

The activity is puzzling experts and drawing the attention of a sleuthing class of preschoolers.

Joe Cannon, a restoration ecologist with the Lands Council in Spokane, said this is the most active he’s ever seen the semiaquatic rodents that have often crossed paths with urban dwellers in the city by the falls.

“They’re always here, they’re just having a bigger presence this year than they’ve had,” said Cannon, standing last week amid a row of trees, near Lake Arthur on Gonzaga’s campus, that showed the telltale signs of beaver chewing.

Cannon studied at Oregon State University in Corvallis and eventually became a member of the Land Council’s beaver project. His work includes consulting about tree damage with property owners, including the owners of the Spokane Convention Center and condominiums on the river’s southern edge. There, too, beaver colonies are believed to be responsible for stripping the bark from several shoreline tree trunks and shrubs.

Jeff Perry, arborist for the city of Spokane, said there’s always been beaver activity in Riverfront Park, but now it’s stretched to areas previously untouched. A row of about a half-dozen cottonwoods near the Forestry Shelter, across the river from the Red Lion Hotel and near Avista’s upper dam, have been wrapped with wire in an attempt to prevent further damage. That was after willows near the Lilac Bowl had been targeted earlier in the winter, leading to the felling of at least one tree into the water, said Perry.

“The big thing is there’s been a lot more activity in the park. We usually see it in the north channel, but now we’re seeing it in the south channel,” Perry said.

It’s that activity that caught the attention of Chelsea Inman’s preschool students at the Community Building Children’s Center. Groups of a half-dozen children, between the ages of 3 and 5, take routine tours through the park and began spotting beaver activity in late November, Inman said.

“We’ve been bringing students to the park for years and never seen beaver activity before,” Inman said.

After finding some downed saplings near the upper dam, kids followed the wood scraps “Scooby Doo-like,” Inman said, to the damaged trees to the west. The trail included some trail-marking posts on the bridge leading between Havermale Island and the river’s north bank. The beavers apparently became confused and started gnawing the wooden markers, believing them to be tree trunks, she said.

On Monday afternoon, Inman’s students gathered in a circle, as they do twice a day, to talk about their investigation and what they learned about the eager animal.

“I think it’s a good idea to let everyone know that beavers were chewing our trees,” said Olivia, 4, who also said her favorite animal was a beaver.

Nelson, 5, said it was important for beavers to have a source of food in the park so they don’t venture into other, more dangerous parts of town.

“They can only eat the park trees, and not the other trees in our city,” Nelson said. “We couldn’t have any fruit, or apple trees, or any pears, or any cherries to eat.”

Nelson’s not far off. The pages of The Spokesman-Review throughout the years show that beavers have made their way into urban areas of Spokane. In October 1937, the city’s utilities director discovered the patriarch of a beaver family sleeping under a steam pipe beneath Howard Street downtown. And in January 1956, the newspaper published an obituary for a beaver that was shot by a police captain on the Post Street bridge, believed to be one of a colony “that has been chewing down trees on the Gonzaga campus.”

“Who knows, perhaps the little monster decided to go on to greater things than the trees. Maybe he was eying the bridge,” the newspaper quotes one “passing patrolman” as saying.

The children in Inman’s class haven’t yet actually spotted a beaver. The creatures are nocturnal, doing most of their feeding and work at night. Inman said she’d love to have her students don some headlamps and continue their detective work at night, but planning that might be too difficult.

“We’re mostly studying what we see,” Inman said.

That’s also what Cannon’s been doing, consulting with the city and owners of the convention center about what to do. Cannon has decided against trying to live-trap the beavers because the traps could be a safety risk.

“It’s kind of big clamshell thing that closes on them,” Cannon said. “If somebody steps in it, it’s bad news.”

The beavers are unlikely to try building a dam with the wood they’ve targeted along the river banks, Cannon said. The creatures will dam still waters, but along the banks of the Spokane they usually build lodges and dens with concealed entrances beneath the water’s surface.

Near Gonzaga, Cannon pointed to some stark white branches stuck in a shallow cove of the Spokane River last week as a likely food source, as well as another sign the animals are nearby.

“That’s a good indication there’s a den there,” he said, pointing beneath the surface of the slowly moving river. “They can comfortably feed there.”

Inman’s class has their own theories about the increased beaver activity. Construction has shuttered the U.S. Pavilion and closed large swathes of meadow and prairie areas, and less human foot traffic could be an explanation for more beavers.

“But it could also be a sign of the health of the river, and that’s a good thing,” she said.

To replant the damaged cottonwoods, the city would need approval from a committee overseeing shoreline landscaping work, Perry said, but there is a permit exemption for environmental restoration.

Cannon thinks the river’s seasonal turbulence could explain all the signs of beavers this spring, along with an expanding population that can live free of natural predators along the banks of the Spokane.

“I think they kind of get trapped a little bit, between the dam and that serious whitewater,” Cannon said. “It’s kind of the conclusion I make. Every year, they get there and eat those trees. But during the summer, they’ve moved on to greener pastures.”