Beavers build neighborhoods. They are like the urban planners of the natural world. Just like human urban planners, they look for certain characteristics in choosing a good place to design a neighborhood. First of all, they need water. Beavers actually live in two feet of water. Being slow, pudgy and awkward animals (don’t tell them I said so), they make easy pickings for predators and without a quick escape underwater they would be dead in no time. Second, they need plant material to eat and to build with. Turns out that willows, aspens, and cottonwoods (all plants that grow near water) are their favorite. With those crazy strong teeth of theirs, they can actually fell large Aspen trees and then push them down a hillside to build elaborate dams and lodges at the stream. This takes quite a bit of plant material of varied sizes, so the plants in the area have to be growing at a healthy rate.
Turns out there is another mammal scoping out the land in this area. We can think of him like a get-rich-quick real estate speculator, planning to make a profit off the land in the short term with no plan for the future health or long term investment of the area. This mammal is the cow. Cows are permitted to graze most parts of the National Forest land in southern Utah and they are attracted to the same waterways as the beaver. Unfortunately cows think willow and aspen are mighty tasty and they chomp them down before the plants can grow enough to create an eligible lot for the beaver.
Who cares you may be wondering? Why does it matter to me that the urban planner wins out over the land speculator? Well, in the human world we have seen parts of Arizona, Nevada and Florida with neighborhoods full of foreclosures or half built condos or urban decay from areas that were bought to flip for profit rather than to live in. In the natural world, we are left with a loss of water and loss of habitat for a variety of animals. Beavers are not just building a home for themselves, they act like urban planners, building an entire neighborhood, an entire ecosystem. When they fell the trees it opens up the forest so that plants that need more light can grow by the streams and ponds. When they build the dams, it slows the streams and filters the water. This means there is more water held along the way for animals to drink and for plants to thrive. It also means cleaner water downstream for all of us. You might think the Aspen trees wouldn’t be too keen on beaver since they are gnawed on by them, but actually Aspens are adapted to it and are quick to put up new sprouts.
Before this week with the Grand Canyon Trust, hiking to beaver dams and measuring the abundance and health of the Willows and Aspens, I had no idea that beaver were so cool and so important. In fact, beaver are considered by most people to be a “keystone species”, crucial to healthy wetland environments. I wish that had been common knowledge back in the 1800’s when beaver were brought to the brink of extinction by fur trappers responding to the demand for beaver pelt hats. Darn fashion fads wiping out thousands of years of sustainable wetlands!