Celebrating Beavers this International Beaver Day

*SLAP* *SLAP* *SLAP* What’s that!? Oh, is it the tail slapping that beavers use to tell each other to watch out for something nearby? That must mean it’s almost International Beaver Day! Every April 7th,  we get a chance to reflect on what these hard-working mammals mean to us! 

The American Beaver (Castor canadensis) is a key player in NY State Parks— so key, in fact, that it is considered a keystone species of its wetland ecosystems, playing a major role in keeping ecosystems healthy. This is because beavers are one of the few animals that truly modify their habitats to better suit their needs, which has given them the title of “ecosystem engineers!”  

Most people associate beavers with their dams, which are certainly their most influential construction projects, but they build other structures too. Beavers don’t hibernate, instead opting to spend the winter in a cozy, dome-like lodge in the middle of their pond with a passageway that provides easy access to water below the ice. A lodge houses a family (colony) of beavers, including a pair of parent beavers and their young (kits). Beavers mate for life and have 3-6 kits a year. Those lodges must get quite snug! 

Beavers also store food caches near the entrance to their lodges, which helps get them through long, cold New York winters. In these caches, the herbivorous beaver stores things like branches, leaves, and green stems that are crucial food sources in winter months.

Diagram of beaver structures. Photo credit: Jennifer Rees, Washington Department of Fish and Wildlife

Their big, watertight dams—made of logs, sticks, mud, and sometimes stone— block running water, creating their own beaver ponds with rich, surrounding wetlands. Beavers constantly work to maintain their dams and build new ones where they hear running water. Beaver colonies can maintain several dams at once, sourcing wood from the forest around their pond. They use their sharp, orange teeth to cut down trees, leaving chewed stumps that can be seen up to 165 feet from bodies of water. Have you ever seen one of these stumps in a State Park? Beavers live in and modify almost any forested body of freshwater from Canada to Northern Mexico, so that’s quite a few waterbodies they may impact.

Living with Beavers

State Parks can be centers of beaver activity, which comes with its own set of challenges between beaver habitation and park infrastructure. Damage to property caused by flooding, plugging culverts, and damage to trees are of particular concern. For instance, Seneca Lake State Park recently wrapped the bases of important trees with chicken wire to prevent beavers from gnawing on them, which worked well.

Other efforts in parks across the state include using devices such as beaver deceivers, culvert protection fencing, and pond levelling devices. Beaver deceivers are a very handy way to keep beavers in our parks while also reducing the risk of flooding for trails, roads, and other amenities we enjoy.

Interpretive programs also play an important role in promoting education and public knowledge of beavers and good beaver stewardship. Trail cameras can allow State Park Biologists to monitor beaver populations and observe their behaviors – and the photos can be used in educational programs too. The Beaver Walk and Talk at Moreau Lake State Park is a very popular educational program that shows off the major beaver lodge at the park. The Bear Mountain Trailside Museum and Zoo is also a wonderful place to brush up on beaver knowledge. Environmental stewardship in NY State Parks is vital to balancing the work of two major ecosystem engineers: beavers and humans. Good stewardship allows for the many environmental benefits of beaver-created wetlands, while also minimizing impacts to park infrastructure. 

Beaver Wetlands

Prime wetland habitat is incredibly beneficial to all sorts of organisms and even the land itself. In terms of why beavers make dams, the resulting pond and wetlands foster growth of aquatic plants like water lilies—some of the beaver’s favorite summertime snacks. Wetlands also protect beaver colonies from predators such as coyotes and fishers. For other animals, beaver-created wetlands are highly productive environments. Amphibians, fish, invertebrates, large herbivores, and waterfowl flourish in these wetlands, supporting predator populations higher up the food chain like raptors, bears, other semi-aquatic mammals like otters, and more.

As for the landscape, wetlands act like a sponge. Wetlands store water in wet periods and release water as the landscape dries, helping to regulate the water table. They also work to filter sediment and more harmful chemicals, which benefits any animal or person using the water downstream. From the wealth of biodiversity to the maintenance of healthy landscapes, beavers can help make the environment strong and resilient, which is necessary to adapt to climate change now more than ever.

Beaver History

Beavers and their wetlands were once much more abundant than they are today, seeing a massive decline in numbers due to the colonial and post-colonial fur trade. Over the course of the fur trade in New York, beavers were sadly on the brink of extirpation (regional extinction) across the Northeast United States and beyond. Beaver populations dropped so low due to unregulated, commercialized trapping for their fur, which was often made into fancy hats. New York was a center of the fur trade as trapping flourished with widespread and abundant beaver populations upstate, coupled with the easy access to navigable waterways, including the Hudson River, Lake Champlain, and the Great Lakes. At the height of the North American fur trade between 1860 and 1870, trading companies reported buying 150,000 beaver pelts per year.

An old, whimsical illustration of beavers hard at work near Niagara Falls from the early 1700s. Photo Credit: Nicolas De Fer, from L’Amerique Divisee Selon Letendue de ses Principales Parties, 1713

From the 1600s to late 1800s, the fur trade grew together with cities like Albany and New York City at the expense of beaver populations. Beavers are displayed on the seals of both of those cities as symbols honoring their fur trading past and allude to values such as diligence and hard work. Likewise, the history of the beaver is tightly linked with the entire state of New York, as shown by the beaver’s status as state mammal. We’re lucky today that beaver populations persist and are not just symbols of fur trade history, unregulated trapping, and all that caused their decline.

Rebounding beaver populations are, fortunately, a great conservation success story. Trapping regulations in the United States and Canada around the turn of the 20th century started the end of the decline. Reintroduction programs (moving animals back to habitats where they once lived) along with perseverant beavers hidden away in high mountains, like the Adirondacks, provided seeds for the growth of new beaver populations across New York and elsewhere. In the 1920s, the Palisades Interstate Park Commission even reintroduced three breeding pairs of beavers back to Harriman State Park!  

Beavers Today

Across their range, beavers number between 10 and 15 million, which is an incredible recovery! But that is only a conservatively estimated 10% of their pre-colonial population. There is much to celebrate about the beaver, but there is still much work to be done. There have been and will continue to be growing pains between beaver populations and people, but if we keep supporting the beaver, then they will help safeguard the natural places we cherish. 

This International Beaver Day, let’s reframe our understanding of the beaver. Beavers may be seen as ignoble rodents, pelts for hats, mere symbols on city seals, or unredeemable nuisances, but let’s try seeing them as wetland restorationists— stewards working toward resilient wetland networks and precolonial environments. There is a lot of work to be done to foster harmony between people and beavers, which will require continual human stewardship, but their own current recovery is a testament to how much good conservation work can be achieved over time. So be eager to get out there and explore your local State Park for dams, lodges, and the beavers that built them! 

A beaver dragging twigs at Allegany State Park. Photo Credit: Michael Head (CC BY-NC-SA 2.0)

More Beaver Facts!

  • Beavers are very large rodents. They can grow anywhere from 26 to 65 pounds and be almost 3 feet long with almost another foot of length from their broad tail.
  • Beavers communicate with each other in a variety of ways. Adults will grunt and young beavers will use high pitched whines. Beavers will even use their big, flat tails to make a loud, slapping noise to warn other beavers in the colony of nearby danger.
  • Beavers have orange teeth. Their teeth are very hard and contain high amounts of iron, which looks orange to us. It’s not just because they forgot to brush!
  • Like other rodents, a beaver’s front teeth (incisors) never stop growing. The length of their teeth is kept in check by being worn down when gnawing wood and are adapted to always stay sharp.
  • Beavers have very special, flat tails. They use their scaly tails to help them swim, communicate, and pat down their dams. A beaver’s tail also helps to store fat and steady their body temperature (thermoregulation).
  • Beavers have webbed back paws that help them swim better, and the second back toes have split nails they use to comb waterproofing oils into their fur.
  • So water doesn’t get into awkward places, a beaver’s nose and ears can close completely underwater.
  • Beavers also have a special membrane for their eyes that they can close to keep the water out called a nictitating membrane, almost like a clear second eyelid.
  • A beaver’s lips close behind their front teeth so they can chew sticks and other plant material underwater.
  • Beavers are also known for what’s called a castor sac (hence their genus name Castor), which holds oil that has a strong smell and is used to make a substance called castoreum. Castoreum has been used as a perfume ingredient, food flavoring with a taste like vanilla, and a traditional medicine. Beavers also groom themselves with the castor oil to keep their fur waterproof. The strong scent of the castor oil makes it great for marking beaver territories, too.
  • Beavers don’t hibernate in the winter and their lodges stay quite a bit warmer than the cold temperatures outside.
  • Beavers are most active at dawn and dusk (crepuscular) and at night (nocturnal), so keep an ear out for tail slaps after the sun goes down.
  • Beaver lodges are so well-built and cozy that other semi-aquatic mammals, like otters or muskrat, might adopt them if the beavers ever move out.
  • Beavers are pregnant with kits from the middle of winter to late spring, so be on the lookout around then for furry, little beaver babies on your adventures in State Parks.

Post by Daniel Fleischman, NYS Parks and Student Conservation Association

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