Exploring with Beavers, Nature’s Ecosystem Engineers

Beavers don’t often go exploring. Perhaps only once a lifetime, when they disperse as juveniles and search for a new home and mate, do they really explore the boundaries of their world. But one beaver family recently went on quite the adventure. That family of nine beavers was captured earlier that week in the north part of Denver. Their final destination, and their new family home, was a crystal clear mountain stream about an hour south of Denver.

Beavers used to live in almost every stream in North America (except in the arid southwest), and number 100-200 million. But as demand for their fur skyrocketed between American colonization and the early 20th century, they were trapped almost to extinction. Today there are about 10-15 million in North America. Despite reintroductions and natural expansion, beavers have still yet to return to many places where they used to live.

A Species That Shapes Its Environment

Beaver are nature’s ecosystem engineers, felling trees and building dams, and changing waterways for their own benefit. But they also benefit other species in the process, including humans as well as many species that are now in jeopardy at least in part due to the historic loss of beavers. Their dams help to control the quantity and quality of water downstream, which both humans and animals use. Their ponds and flooded areas create habitat for many plants and animals, such as fish, birds, insects, and amphibians. In fact, some species only live near beaver ponds. Beavers dramatically change their environment, and those changes can last for hundreds of years, even after the beaver have moved on.

This specific beaver family’s former home, a stream on the north of Denver, is slated for re-alignment this winter. The stream engineering will destroy the beaver’s home and habitat. But officials knew it would be a shame to lose the natural engineering benefits that these beavers can provide. So, Denver’s Department of Parks and Recreation contacted Wildlife2000, a local non-profit organization focused exclusively on beaver relocation, and Defenders to live-trap and relocate the beavers to a place where they would be safe and could help create important habitat for other species.

Helping a Beaver Family to a New Home

First, we secured approval from Colorado Parks and Wildlife, an essential step for any wild animal relocation. Then we went to work. For three days in a row, live-traps were set out in the late afternoon, hidden along the shoreline within the vegetation, and baited with a lure that beavers find irresistible. To humans, it smells like a musty, organic, woodsy scent. Not unpleasant, but probably not destined to become a bestselling fragrance. At daybreak, staff and volunteers with Wildlife2000 and Defenders checked the traps, hoping to see movement. The first night we caught four beavers: one adult, two juveniles, and one kit. The second night, even though three of our four traps were tripped intentionally by a passerby, we still caught a juvenile in the only trap hidden enough to be missed. The third night, we caught four more beavers, including the matriarch, a mature 40-45 pound beaver.

On the day of relocation, we got an early start moving and packing the beavers into large cages for transport: two adults per cage, and all three kits in their own little cage. We loaded them into the back of two trucks, and hit the road. Just an hour later, we were unloading the cages from the trucks, and loading them onto the back of an ATV. We secured our passengers with an army’s worth of straps and bungees, making sure our precious cargo was safe and secure. The whole time we were loading, the beavers seemed more curious than anything, taking in their new surroundings and crisp mountain air. Then, we were off down the mountain, our destination a clear stream in the valley below, accessed by miles of tight trails hugging the side of the mountain. It was slow going, but the ATV, the trails, and the beavers cooperated, and finally, we arrived.

We unloaded the cages and placed them in the stream. When the moment came to release the family, they slowly and cautiously moved out into the water. They explored, found the other members of their family, munched on some vegetation, and explored some more. Despite the long journey, they behaved exactly how beavers are supposed to do. After an hour, we left the family in their new home.

The family will probably move a little bit upstream or down, but eventually they will find the ideal spot. They will start to build a dam, creating a deeper pool for themselves where they can build a lodge, and creating habitat for other plants and animals as well. Within a year, the area around their home will be quite different; within five years, even more changed. New plants and animals will move in and take advantage of the beavers and all their hard work. Defenders will return regularly to monitor the results and learn lessons for future beaver restoration efforts. Relocating this family was a definitive win-win, for them and for all wildlife where they are making their new home.