The upside to beavers, a valuable rodent

SALISBURY — Ben Goldfarb, author of “Eager: The Surprising, Secret Life of Beavers and Why They Matter,” told a Zoom audience of more than 150 people that beavers and their activities are highly beneficial to the environment. Goldfarb’s talk, sponsored by the Scoville Memorial Library, was on Saturday, March 6.

The beaver is a rodent, Goldfarb explained. The animals typically weigh between 40 and 50 pounds.

They are semi-aquatic, and can stay underwater for as long as 15 minutes.

The most prominent feature — the large, flat tail — is a “multi-purpose tool,” serving as rudder, fat storage system, “kickstand” and internal climate control mechanism.

Beavers eat almost any deciduous tree, and assorted grasses and other vegetation. Goldfarb said the animals are “choosy generalists.”

And of course beavers use trees as construction material, building lodges and dams.

A beaver lodge houses between two and eight beavers in a family unit. By the second year of their lives, beavers leave home and strike out on their own. Beavers are generally monogamous and mate for life.

Why do beavers build dams? On land, Goldfarb said, a beaver is a “fat, slow, smelly package of meat.”

But in water the beaver moves easily, avoiding predators.

So the dams create ponds and marshy areas, where the beaver is safe.

Beavers are also prolific diggers, creating canals to travel through and get to more trees.

Fur trapping in the Colonial and early United States was an enormously important business. Beaver pelts were especially valuable, so much so that the Oregon Territory issued a coin equal to the value of a beaver pelt.

But the trapping took its toll, and by the end of the 19th century the beaver population plummeted from a pre-Colonial high of perhaps 400 million animals to almost none in the lower 48 states and a relative handful in Canada.

Goldfarb said this near-extirpation had serious environmental ramifications. Describing the beaver as a “keystone species,” he noted that the habitats beavers create also serve waterfowl and fish species, and serve as firebreaks and filtration systems for water.

The importance of beavers was recognized by the early 20th century and beavers were reintroduced across the continental U.S. 

One effort in Idaho, in 1948, saw 76 beavers in special boxes attached to parachutes dropped into remote areas. Of the initial group, 75 survived the experience. (Goldfarb said one beaver, alas, managed to get out of the box a little too early.)

In just a year the beavers had created ponds and wetlands.

“It was very successful,” Goldfarb said.

Coping, not killing

Contemporary beaver management sometimes involves killing them when they cause problems — flooding of roads or yards, for instance.

But there are plenty of non-lethal methods. Goldfarb noted one site in Colorado where landowners installed fencing around trees they wished to protect from beavers, while leaving unwanted, non-native trees unprotected. The beavers obligingly ate the unwanted trees.

There are other methods, such as running pipes through beaver dams, thus “creating a leak” and preventing backups that flood roads and yards.

And beavers are regularly relocated, and the people doing the relocating often build the animals lodges to get started with.

Looking forward, Goldfarb contrasted a photo of a freestone mountain brook “(“looks like something in a fly-fishing catalog”) with a photo of a swampy area, with trees in standing water.

The latter vista doesn’t appeal to people accustomed to thinking of wetlands as undesirable.

“So we have to remember what our lands are supposed to look like.”