"Sherri has educated herself, and she truly knows what she's doing," says Delia Malone, an ecologist with Colorado State University's Natural Heritage Program who's worked with Tippie on a few relocation missions. "A lot of professional wildlife biologists get a bit removed from their job. Sherri loves what she does, and she does it because she loves it. She doesn't have a strictly objective approach. She's very subjective, which I think is wonderful."
That subjective approach is in full swing as our ATV reaches the top of the ridge and our destination: a large, well-shaded pond. Eager as she is to release her captives, Tippie first gives the area a careful inspection, like a mom sizing up the dorm where her darling child is going to spend the next four years. Beaver are vegetarians and have been known to consume all sorts of shoots, fruit and tree bark, but they prefer willow, aspen and cottonwood trees. The willow supply is a little further from the pond than Tippie would like, but there seem to be enough young aspen in the area to compensate, and more than enough trees for the beaver to start building a dam and a lodge and stashing caches of food for the winter.
Tippie and the ranch manager carry the cages to the edge of the pond and open them. The beaver waddle eagerly into the water. "Go, babies! Go!" Tippie urges.
Connie Harvey watches with a grin as they swim off. A prominent environmental activist and the owner of the ranch, Harvey's been aiming to get beaver into this pond for some time. She's seen what they can do at her house outside of Aspen, on Maroon Creek. She's had to fence some mature aspen she wants to protect from their teeth, and she once had to wear hip waders to cross her yard, but having beaver as neighbors has made the area much more interesting.
"We're not trying to have a manicured place," she says. "I like a little wilderness, and the beavers like it, too. They make it so nice and cool there, even on the hottest summer days. They're amazing."
Harvey and Tippie watch the six new arrivals explore the pond, checking out its possibilities. After a few minutes, one of the adults climbs out on the opposite bank and engages in some quick freshening up, wielding a special claw on the webbed back foot that's used for grooming as well as picking splinters from between chisel-shaped incisors.
"I think they're going to like it here," Harvey says.
"They're loving it," Tippie says. "They're in heaven."
Two centuries ago, before the arrival of the trappers and the miners, Colorado's mountain streams and rivers looked quite different from the way they look today. They were not in such a hurry to scour out everything in their path. Their velocity was slowed by a seemingly endless series of terraced ponds and dams, serene pools that attracted a tremendous diversity of waterfowl and fish. Their channels were deeper, their flow more uniform, with greater stability in drought and flood years. They were surrounded by lush grasses, wetlands and trees rather than skimpy, sun-baked vegetation and rocks.
One of the key factors in the change is the removal of beaver from the area, Colorado State University professor Ellen Wohl notes in Virtual Rivers, her book about the state's altered waterways. Without beaver, she writes, "the rivers have become more efficient conveyors of sediment but less-diverse ecosystems."
"Even very large rivers, like the Colorado, had beaver on them," adds ecologist Malone. "There's been a dramatic decline in our riparian wetlands, for a lot of reasons, but one of them is clearly the lack of beaver. In the long term, they're essential to the health of the ecological system."
Prior to European settlement, an estimated 60 million beaver were at work in North America; researchers believe there may be just a tenth that number today. In major river systems such as the Upper Mississippi and Missouri River basins, the reduction has been even more drastic, with beaver ponds now found in barely 1 percent of the acreage they covered in 1600.
In Colorado, trappers and settlers waged a ferocious war against the critters for more than a century. Dams were torn out, creeks diverted for irrigation, mining and other industries, food sources turned into fuel and housing. The beaver themselves were turned into hats and wraps.
In recent decades, the beaver population has recovered to some extent — but only in areas where there's still adequate habitat. Even today, people who want to reintroduce beaver to their historic range are often confronted by neighbors exhibiting what Sherri Tippie calls "the golf course mentality," people who don't want beaver messing with trees or well-regulated waterways.