Beavers & Climate Change

Beavers: Furry wetlands residents with buck teeth and a paddle tail. Also, New York State’s official mammal since 1975! Once in a while they pop up cutely on social media, or make news when a dam is associated with inconvenient flooding, but other than that, do you think about beavers much? Beavers are an important species in several ways, so it’s time we give them their due. Let’s talk about their role and their impact on the environment.

From the time the earliest settlers, beavers were sought for their pelts. Beaver skin was traded heavily into the 19^th Century thanks to the European fashion industry. At the same time, New York’s timber, on which beavers rely, was also in high demand. Demand for both the fur and timber was so high, in fact that the species was almost eradicated from the Adirondacks by 1840. With restoration of forests in the 20^th Century and beaver fur going out of fashion, beaver populations rebounded. So much so, in fact, they had become a $5.5 million nuisance by the 1940s. Since then both management and protection policies have been established to ensure healthy population numbers. There are an estimated 10-15 million beavers in North America today. According to the United States Department of Agriculture, there were once between 60 million and 400 million beavers in North America before European settlers arrived.

Now let’s talk about how beavers shape their environments. Though large rodents that swim very quickly, beavers have adapted to avoid predators by shaping the environment to their advantage. Damming a river or stream to the ideal depth allows them to build multi-generational lodges that have only underwater entrances and an opening just large enough on top for ventilation–they stay cool in summer and warm in winter. When beavers dam a stream or river, it diffuses concentrated streams of water into wider bands of slower-moving water which reduces erosion, and supports wetland conditions around a pond or marsh. And wetlands are very good things in many cases.

What’s so great about wetlands?

Wetlands purify polluted run-off water from artificial surfaces. Reduced flow of water in beaver dam areas allows nutrients that have washed away from other areas to collect. Those nutrients break down contaminants like pesticides and herbicides, preventing them from traveling downstream and collecting in water bodies where they can harm fish and other wildlife, and impact vegetation living there.

Beaver ponds and wetland areas increase biodiversity. Thousands of terrestrial and aquatic species of plants, animals, and organisms call these areas home. In fact, the beaver dam itself often serves as home to other animals such as muskrats, mink, and river otters. Waterfowl, such as ducks, fare much better in beaver-active areas than in other bodies of water. Swans and geese prefer to nest on beaver lodges, which are stable and protected from many predators. Amphibians and fish do exceptionally well in beaver-altered environments too. According to Cornell University, 25% of wetland species rely on beavers to survive. For all that beavers do for to support biodiverse communities of species and the environment, they are considered a keystone species.

Wetlands reduce flooding by absorbing influxes of water, and slowing the flow of excess water. By contrast, areas that are normally dry don’t absorb water as readily, which allows fast moving runoff, erosion, and flooding. Wetlands act as reserves for water tables, replenishing them during dry spells. Wetlands are also resistant to the ravages of wildfires. These latter two characteristics of wetlands will prove increasingly important as temperature fluctuations and extreme weather incidents accelerate due to climate change.

Ecosystem engineers.

Speaking of climate change, beavers combat climate change directly, too, by sequestering carbon. A 2018 ScienceDaily article estimates that beaver ponds and meadows can sink as much as 470,000 tons of carbon annually. The work of beavers has been likened to coral reefs and rainforests in their environmental impact in North America by the Beaver Institute. It’s no wonder beavers are so frequently referred to as the engineers of ecosystems, second only to humans in their ability to transform the character of landscapes.

So the next time you see evidence of beaver activity, or hear about beaver dam construction, before you think about the inconvenience there may be from flooding, consider what this little marvel of nature is trying to do, and everything that could be lost in the future if he is prevented from doing his good work.