by Inger Giuffrida, executive director, WildCare Oklahoma
Before beavers were hunted to the
brink of extinction for their fur, the
North American beaver population was estimated to be 400 million. Extirpated from most states, including Oklahoma, by the early 1900s, beavers have been reintroduced into many areas. Today, the North American beaver population — estimated at nine million to 12 million — is a small fraction of the numbers that existed on the continent before the careless overhunting of European settlers. But the return of the beaver to many areas, including Oklahoma — which reintroduced beavers in 1950 — has not come without controversy.
To understand the situation that faces beavers in Oklahoma and beyond, it’s important to understand exactly what a beaver is and the effects this special animal has on its environment.
What Is a Beaver?
Beavers are the largest rodents in North America. An adult can weigh as much as 65 pounds. The two most notable physical
characteristics of beavers are their big, flat tails and large front teeth. Their incisors are orange tinged because of the ironrich enamel that coats them. That makes beavers’ teeth extra hard, allowing them to chew through trees.
The tail helps to propel the animal gracefully through water, but it is also used in communicating with other beavers by slapping the tail in warning about potential danger. Beavers also use their flat, sturdy tails to help give them balance and leverage when gnawing on trees. Despite
Snow does not deter this beaver from its daily activities at WildCare Oklahoma. Photo by Laura Kintz, WildCare Oklahoma.
January / February 2024 • OKC Pets 27
popular depictions of beavers, they do not use their tails to place mud, sticks, and trees when building lodges and dams. They use their dexterous hands for those tasks.
What Beavers Build
Beavers are known for building dams in the area that they call home. As in human dam building, this is done to control the flow of water. It also ensures that the entrances to beaver homes, called lodges, are underwater to provide extra protection for beaver families.
Beavers are known to be industrious, hence the term “busy as a beaver.” Like any good homeowner, they constantly maintain and in some cases expand their dams and lodges. Commonly, the lodges are islands. Although much of the lodge is below the waterline to accommodate entrances and exits, the living quarters are above the water. Extremely well-insulated, the lodges have ventilation holes to ensure good air quality. Beavers also cover the floors of their lodges with wood shavings that they make themselves, thus creating a warm, dry, and cozy living environment.
Beavers are crepuscular, meaning they are most active with their building activities during dawn and dusk. That is one reason people don’t commonly see beavers.
What Beavers Eat
Beavers are herbivores that eat leaves, stems, aquatic plants, sticks, and even the trees they use for building dams and lodges. They spend the summer gathering food, and they store it in their lodges for winter. Because the stored food is partially submerged in cooling water, the leaves and branches stay fresher longer.
Where Beavers Live
North American beavers live throughout North America, including Oklahoma — in ponds, lakes, streams, and rivers. They are semiaquatic mammals that live equally in water and on land. They can stay underwater for six to eight minutes. Wherever there is a permanent body of water, there is a chance you might find a beaver. And where there is one beaver, there usually are many.
Beaver Families
Beavers live in family groups and are monogamous, meaning they mate for life. Each year, a pair of beavers will have as many as four kits. The youngsters remain with the parents for as long as two years, with the older offspring helping to rear their younger siblings. So a beaver family can have eight to ten members.
Beavers Are a Keystone Species
North American beavers are a keystone species. The term “keystone species” comes from the stone in an arch that prevents the arch from falling — the keystone. Remove the keystone from the arch, and the entire arch collapses. A keystone species is one on which an ecosystem and its inhabitants depend. Remove the keystone species, and just as in the case of a stone arch, the ecosystem collapses or is changed drastically. Many of the species in an environment — including grasses, trees, plants, aquatic species, insects, reptiles, amphibians, birds, and mammals — cannot survive without the keystone species and the ecosystem services it provides.
Some keystones species are predators, such as wolves, which keep populations of elk and deer sustainable. When wolves are extirpated, elk and deer populations increase. Those ungulates need to forage, and overbrowsing of trees and shrubs occurs, resulting in erosion, loss of shade, and loss of habitat.
Keystone species can also be prey such as prairie dogs, plants such as the saguaro cactus, or mutualists — two species with a mutually beneficial relationship that also benefits the broader environment — such as pollinators, as in bees and plants.
North American beavers are a keystone species because they are ecosystem engineers. Beavers create or enhance freshwater habitats, including wetlands, through their building activities. A wide variety of creatures thrives in beaver ponds and their associated wetlands — insects, spiders, frogs, turtles, fish, other aquatic life, ducks, geese, herons, rails, bitterns, songbirds, owls, otters, and others.
Beavers Benefit Humans Too
The habitats that beavers create benefit humans too. Beaver activities help maintain the water table that human
life depends on. Because their dams and lodges slow water flow, they provide time for water to recharge. The slowing of water
flow through beaver-engineered areas also mitigates the effects of catastrophic flooding and wildfires. Areas managed by beavers are shown to sustain significantly less damage.
The wetlands that beavers create help to filter and trap sediment and excess nitrogen and nutrients (caused by fertilizers and pet and yard waste) common in stormwater runoff. If those chemicals are not prevented from flowing into ponds and lakes, they cause algae blooms, which diminish water quality and deplete the supply of oxygen to fish and other aquatic species. This beaver-built filtration system improves the quality of water as it travels through the watershed and prevents the die-off of fish, amphibians, and reptiles that depend on healthy water.
Because of their diversity and abundance of foliage, beaver-engineered areas sequester substantial amounts of carbon from the atmosphere — carbon that causes climate change, leading to extreme weather, including heat waves, out-of-season droughts, floods, and fires.
People’s Intolerance of Beavers
Despite the incredible benefits that beavers provide to the environment and to a wide range of plant and animal species, including humans, beavers often find themselves on the losing end of conflicts with
humans. When beavers were reintroduced into Oklahoma, plans were not created to help landowners manage beaver behavior that was found to be intolerable or destructive. When a property owner does not like the effects of beavers’ ecosystem building, the animals are destroyed.
Commonly trapped in underwater body-grip or torso-hold traps, beavers are simultaneously crushed while being slowly drowned. On land, leg-hold traps are used. These clamp onto the beaver’s leg, holding the animal in agony. Although some people check traps regularly, many allow the animals to languish for days and eventually succumb to starvation. The beaver lodges are indiscriminately bulldozed or blown up.
It is often because of those activities that WildCare Oklahoma receives beavers into care. Orphaned baby beavers are discovered because their parents and older siblings have been killed. In some cases, beavers survive the traps and are maimed and brought to WildCare for medical care. Since 2015, WildCare has admitted nearly 50 beavers for care.
Managing the Effects of Beaver Activities
Many effects of beaver activities can be managed. First, people can choose to avoid living near permanent bodies of water.
Beavers cannot survive without living on ponds, lakes, streams, or rivers. People can.
Beavers need trees to build their lodges and dams. To attempt to protect specific trees from beavers, homeowners and landowners can use caging, electric-shock fencing, metal flashing around the trunks, or a mixture of paint and sand applied directly to the trunks.
Regarding flooding, which often occurs at culverts, flow devices can be installed. Several companies can be hired to do this work, and people can also build do-it-yourself versions of the devices. These have proved to be most cost-effective in the short term and long term.
When a beaver family is eliminated, in all likelihood, another will move in. It’s a constant battle, which results in many dead beavers and frustration for people. Flow devices and tree protection can help people live with beavers in many situations.
With an increasing number of ever hotter days and longer droughts, we will only benefit from the environmental engineering of North American beavers.
In the next year, WildCare will work with others to develop a strategy and resources to help landowners manage some of the initial negative outcomes that beavers bring and live with all the benefits that they provide — improved water quality, consistently maintained water table, mitigation of fires and catastrophic floods, carbon sequestration, and increased biodiversity in beaver-built or beaver-enhanced areas.
WildCare Oklahoma has the only native-wildlife hospital in Oklahoma staffed with a full-time veterinarian, two registered veterinary technicians, and a veterinary assistant. For more information, contact [email protected] or visit the website at www.wildcareoklahoma.org.
