Don’t Fear The Beaver
Tree-cutting, Paddle-thumping Rodents Are Thriving in Denver’s Waterways
Story and photos by Reid Neureiter
For the GPHN

Concerned about global warming? Out of control wildfires? Soil erosion? Water quality? Loss of species? One part of the solution may be that busy nocturnal rodent of legend—the North American beaver, castor canadensis. Once trapped to near extinction, the species today is thriving in Denver’s urban waterways.
According to Denver beaver advocate Sherri Tippie, by harvesting trees, building its dams and digging canals, these 50 to 80-pound animals with paddle-shaped tails can transform otherwise barren landscapes into flourishing wetlands. In doing so they create environments for dozens of species of fish, reptiles, birds and larger mammals.
National Geographic’s September 2020 issue contained an extensive article titled, “How beavers became North America’s best firefighter,” explaining that the animal “creates fireproof refuges for many species, suggesting wildlife managers should protect beaver habitat as the U.S. West burns.”
Tippie, an expert in humane beaver relocation and author of the pamphlet Working with Beaver for Better Habitat Naturally, says that most all of Denver’s area waterways have beavers, including the South Platte, Bear Creek, Cherry Creek, Sand Creek, and Tollgate Creek in Aurora.
One does not have to go very far or look very hard to see evidence of Denver’s beavers. There are at least three beaver dams along Cherry Creek between University Boulevard and South Monaco Parkway.
And along the South Platte River, just west of the National Western Complex, over the months of September and October, a very busy beaver (or family of beavers) took down a number of cottonwood trees adjacent to the bike trail, working just feet from the path of oblivious cyclists. One tree was so large (with an 18-inch diameter trunk) that the Denver parks department had to send out a crew with chainsaws to clear the downed log.
Trees that are targets of beaver activity are obvious on close inspection. They have stripped bark and characteristic gnawing marks a foot or two from the ground, with the trunks surrounded by wood-chips. Actual beaver lodges are harder to find. Tippie says that many beavers build “bank dens” or “bank lodges.” These are burrows in the side of streambeds hidden by layers of sticks and branches, which are harder to find than the traditional teepee-like domed lodges seen in a mountain pond. Tippie says that late fall is a very active time for beavers, as they are busy building caches of food before winter arrives.
An ecosystem for everybody
The City of Denver supports co-existence with beavers. Vicki Vargas-Madrid, wildlife program administrator for Denver Parks and Recreation, says the city’s beaver management objectives include minimizing potential conflicts related to beaver activity, and supporting the animals’ role in the urban environment.
Educating Denver city-dwellers about the importance of beavers to the ecosystem, she says, is most important. People sometimes get upset when they see a fallen tree, says Vargas-Madrid, “but we have lots of trees … and beavers take only what they need.” Vargas-Madrid described a conflict last winter when bicycle path users were upset a beaver dam had flooded part of the Cherry Creek trail, which then iced over. “We started to get complaints. Riders did not want to take another path,” she said.
Denver’s beaver management program includes tree and vegetation assessments. For trees that are deemed worth protecting, such as certain cottonwoods, willow, ash, or newly-planted landscaping trees, city officials may fence their bases with heavy gauge steel wire mesh. They also paint bases of some tree trunks with a 50/50 mixture of paint and sand, and leave other undesirable trees and vegetation for the beavers.
At some beaver-dammed waterways, Denver installs water flow control devices to prevent excess flooding. One successful trademarked flow device is called the “Beaver Deceiver,” the website of which advocates against trapping or killing nuisance beavers. “Because wetlands are so important,” notes the website, “beavers might create more value for other wildlife and society than any other animal on Earth.” Vargas-Madrid agreed that trapping and re-location of beavers is not a preferred option. Beavers are territorial, and removal of one beaver means another will just come along to replace it.
The secret life of beavers
A visit to a stretch of Cherry Creek three miles south of Park Hill reveals the remarkable environmental transformation that a thriving beaver family can bring. It’s a prime example of what environmental journalist Ben Goldfarb chronicled in his 2018 book, Eager: The Surprising Secret Life of Beavers and Why They Matter, where he described beavers as the ultimate keystone species: “that rare organism that likewise supports an entire biological community.”
The area lies between Place Bridge Academy at 7125 N. Cherry Creek Dr. and Cook Park to the south. Just below the pedestrian bridge that crosses Cherry Creek is a four-foot high beaver dam, built from August to October. The normally sandy, inches-deep creek bed has been transformed into a placid, several foot deep, 200-yard-long pond with a water level that has risen and widened to create several islands of grass and inundated a number of trees. During a recent visit, numerous ducks were feeding in the calm waters and a belted kingfisher perched above, looking for a meal.
Beavers are nocturnal and crepuscular, meaning they are most active at twilight and at dawn. This can make seeing an actual live beaver harder than seeing evidence of its work in the daytime. Tippie recommends going to a location of obvious beaver activity near a creek or stream after dusk or before dawn, and sitting quietly. After dark in October, this reporter saw and photographed two busy beavers maintaining their dam on Cherry Creek, swimming back and forth under the pedestrian bridge. Vargas-Madrid identified Westerly Creek, just east of Park Hill, as another location for beavers in Denver.
Beavers can be surprisingly large, between 50 and 80 pounds fully grown. But, according to Tippie, they are not dangerous. A beaver will slap its paddle-like tail loudly in the water as a warning if startled, but will generally flee from people.
So, stay up late, or get up very early. and visit a local Denver creek. You might be rewarded with the sight of North America’s largest and most industrious rodent.