Beavers on the Landscape
- jamesreddoch
- Jul 17
- 3 min read
Updated: Jul 18
By Larry Ely
I’m often startled while hiking near the Androscoggin River by sudden, loud slaps coming from the water. It never fails to surprise, until I remember: it’s just the resident bank beavers that make their home at this turn above the river. I really should expect it by now—after all, I’ve already passed the many chewed stumps that mark their handiwork along the trail.
Beavers have been present in parts of North America for more than 7 million years and helped reshape our local landscape after the retreat of the last glacier some 12,000 years ago. The returning beavers began to alter the glacial-melt stream flows through the new mountain valleys and to a large extent engineered the ecosystems we experience today.
By some estimates, between 60 million and 400 million beavers might have been present over the North American continent before the 18th century fur trade drove them to near extinction. Reintroductions and legal protections have since boosted the population to an estimated 10 million to 15 million today. In New Hampshire, there were an estimated 240 beavers present and only in Coos County in 1915, with a rebound to a statewide population of 7,000 by 1940. Beavers have now reached a carrying capacity primarily imposed by conflicts with human development.
Today’s beavers continue to engineer our natural landscape with the benefit of reduced water velocity in streams and rivers, maintenance of in-channel water levels, and enhancement of floodplain storage capacity in the natural systems where they are allowed to exist. Conflicts with humans and our developed infrastructure now limit the beavers’ valuable work. Humans and beavers are the only mammals in our region able to substantially engineer ecosystems for our own benefit.
Beavers are uniquely qualified for the life they lead with an ability to be underwater for up to 15 minutes at a time. They are semi-aquatic with large webbed hind feet, dextrous forepaws for digging, feeding, and gnawing, and they have a thick layer of fat for insulation and a fur waterproofed by the castoreum they secrete. They are able to see underwater due to a nictitating membrane protecting their eyes and also able to seal ears and nostrils while underwater. They are even able to gnaw branches underwater as their lips are sealed behind their front teeth, which are often orange from a protective enamel layer and always growing as they wear away from gnawing of trees and branches. Even the odd shaped paddle tail is especially useful as it acts as a rudder and steering aid in the water and provides balance while on land. The tail also stores fat reserves and communicates danger to the colony by slapping the water.
Better suited to a life in water, beavers are more clumsy on land and must be ever vigilant for predators. They are usually only active outside the den between dusk and dawn. They mate for life and produce one litter of 2 to 6 kits each year, with the kits remaining with the family unit for two years to learn life skills before venturing out on their own and beginning their own eco-engineering.
Beavers make their homes here in the higher elevations by damming streams and building beaver lodges in created ponds, while utilizing bank burrows extending into the riverbank and constructing lodges or burrows in the nearby wetland channels.
Thanks to MLT’s protection of much of the wild Androscoggin River corridor through Shelburne and Gilead, beavers are allowed to thrive there and “be busy” without human conflicts.
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