The American beaver (beaver canadensis) is a keystone species whose ponds and wetlands help replenish groundwater, serve as buffers against forest fires, and provide habitat for a wide variety of wildlife. Once trapped almost to extinction, these industrious animals have since made a remarkable comeback. However, tens of thousands of beavers continue to be killed each year, often in response to damage caused when they fell trees or build dams that flood roads or nearby agricultural fields. Fortunately, non-lethal measures such as chain-link fences, flexible pond levelers, and culvert guards can be used to protect property while allowing beavers and other species to thrive. For these reasons, AWI is working to support and expand the use of these methods nationwide.
Beavers are skilled engineers, well known for their ability to build dams to create ponds that provide refuge from predators and serve as larders to store food. They also build large pavilions that provide shelter and a safe place to raise their young. Beavers form monogamous pairs and usually live in family groups of up to eight related individuals, called colonies, consisting of parents, their young from the previous year, and, in the spring, their young from the current year. The older siblings help with infant care, food collection, dam construction, and lodge cleanup. Beavers are well adapted to their aquatic lifestyle, having large webbed hind feet, transparent membranes over their eyes that function like goggles underwater, and extremely dense fur that repels water and insulates against the cold. And beavers are famous for their large, flat, scaly tails, which store fat during the winter and can be used to warn family members of danger with a powerful slap against the surface of the water.
It is believed that between 60 and 400 million beavers once inhabited the waterways of North America. With the exception of southern Florida and the more arid regions of Nevada and southern California, beavers historically occupied most rivers, streams, and lakes from coast to coast, from the border US-Mexican line to above the Arctic Circle.
Beginning in the 1500s, however, Europeans began trapping beavers for their fur, particularly the prized underfur widely used at the time to make felt hats. By the end of the 19th century, commercial trapping had decimated the population. Across the continent, only 100,000 beavers remained. Since then, the population has rebounded to about 10–15 million, and beavers now occupy much of their former range, although in far fewer numbers and at lower densities than ‘previously.
Although no longer threatened with extinction, beavers continue to be killed in staggering numbers. Every year, tens of thousands of animals are trapped, trapped and slaughtered in almost every corner of the country. Recreational trappers catch beavers for the few dollars that their fur and castoreum (a secretion that beavers use to mark their territory and humans use to flavor and flavor food) might fetch. Wildlife Services – a US Department of Agriculture program that operates largely under the radar – kills beavers in response to the damage they sometimes cause by cutting down trees and flooding roads, railroads and farmland . Most of these killings, however, are cruel, environmentally degrading and unnecessary.
It’s cruel because beavers are often ambushed with steel jaw traps, the jaws of which clamp with bone-breaking force on their limbs, causing excruciating pain. Beavers are also frequently strangled in snares and crushed in body grab traps (Conibear) – large rectangular devices with metal bars designed to close over an animal’s body. Some traps are set specifically to hold beavers underwater until they drown. Because they are physiologically adapted to hold their breath while diving for long periods, however, death by drowning is a slow process for beavers.
Killing beavers is also ecologically detrimental. Beaver ponds and lodges provide shelter and food for dozens of species of fish, birds, amphibians, reptiles and mammals, including some listed as threatened or endangered under of the Endangered Species Act. Beaver ponds also produce an assortment of aquatic insects and lush riparian vegetation, which provide food and shelter for dozens of species of waterfowl and migratory birds. Flood-killed trees attract woodpeckers and provide excellent nesting habitat for many types of birds. Salamanders, frogs, newts and toads use beaver ponds as breeding habitat. Dozens of fish species have been documented in beaver ponds. Moose are attracted to the willows that bloom in the wetlands created by the beavers.
In addition to creating wildlife habitat, beaver-modified landscapes provide other important ecosystem services. Studies indicate that areas riparian to beaver dams are three times more fire resistant than surrounding areas and can provide refuges for wildlife during and immediately after wildfires. Beaver ponds help mitigate the negative effects of climate change by lowering the overall temperature of waterways and storing water accessible to animals and vegetation during times of drought. Beaver dams can also improve water quality by reducing sedimentation and removing toxins from the water column.
The central role of beavers in building and maintaining the wetland ecosystems that serve so many other species, including humans, is why they are so commonly recognized as ‘keystone species’ and ‘ecosystem engineers’.
Killing beavers not only raises welfare and ecological concerns, but is also rarely, if ever, necessary. First, fur trapping today is primarily a hobby, not a livelihood. In a 2015 national survey by the Association of Fish and Wildlife Agencies, 78% of trappers said it was “not important at all” as a source of income.
Second, beavers do not need to be killed or dams destroyed to protect property. Trees can be protected by surrounding them with a wire mesh fence or by coating their trunks with a mixture of paint and sand that deters chewing beavers. Roads, cultivated fields and other human property can be protected from flooding caused by beaver dams through the use of flow devices – systems of pipes and fences that allow a certain amount of water to flow through the dam, thus maintaining the pond at an acceptable level for humans but still beneficial to beavers and the myriad of species that use the habitat created by beavers.
Flow devices can also prevent beavers from clogging culverts (pipes that carry water under roads and railways). Culvert protection fencing has proven effective time and time again in preventing blockages caused by beavers. Several studies indicate that a heavy-duty wire mesh fence installed in a rectangular or trapezoidal configuration upstream of the culvert provides a durable solution.
These measures are not only reliable, but also more effective in the long term because, inevitably, the beavers come back. As the Oregon Department of Fish and Wildlife explains, “beaver removal is often a short-term solution, as other beavers will move into the area if suitable habitat is present.” They also rebuild, as the same document notes: “Generally, the removal of the dam is a futile effort because the beavers quickly rebuild the dam, sometimes overnight.
Another advantage of flow devices is that they can be more cost effective than lethal methods. A study in Virginia compared the costs of repairing road damage caused by beavers at 14 sites before and after the use of flow devices. The authors calculated that the “before” costs of preventive road maintenance, damage repair, and deadly beaver removal were over $300,000 per year. In contrast, the report concluded that the installation costs of debit devices involved a one-time expense of less than $45,000 and maintenance costs of only $277 per year. In addition, the flow devices offered more protection: Prior to their installation, flooding and road damage occurred every year; three years after their installation (when the study ended), no flooding or road damage had yet occurred.
To help promote the use of these ethical, environmentally responsible, and affordable solutions, AWI has long supported the efforts of the Beaver Institute, a Massachusetts-based nonprofit that educates the public about how beavers benefit ecosystems, works with landowners and local governments to install flow devices and other preventative measures, and train wildlife professionals how to properly install and maintain them.
The AWI is also working to develop a federal program that would provide states, tribes, agencies, local governments, landowners, conservation organizations and others with resources to implement non-lethal solutions to conflict. with beavers. We envision that such a program would help make flow devices and other mitigation measures easily accessible to rural and urban communities across the country willing to live with, rather than conflict with, their tailed neighbors. flat and dam builders.