Beavers to the rescue. This story reminded me of the re-introduction of wolves in Yellowstone National Park over a decade ago. The re-introduction of the wolves changed the courses of rivers, and re-balanced the ecology of the region. The re-introduction of beavers is doing the same thing in many parts of the world. It was our fault that the wolves and beavers disappeared in the first place by hunting them to extinction. Are we finally learning not to mess with nature’s balance? One can only hope.
Standing at the edge of a precipice, under a scorching sun in eastern Utah, you can see nothing for miles but the State’s towering buttes. There are no trees to offer welcome shade, the only vegetation is dry scrub that clings to the flat, dusty plains, and the sheer cliffs are barren of life. However, if you happen to glance down into the depths of the canyon that lies at the bottom of the desert’s sandstone mountains, you will see a lush oasis, blooming with green vegetation, and the Price River snaking through the rock. If you scramble down, and watch patiently for long enough, you might even spot some beavers – the very architects of this thriving wetland landscape, smack bang in the middle of the desert.
Beavers used to be prevalent worldwide, ranging from Scotland to Spain, Syria to Russia, and Canada to Mexico. The fur trade of the 1500s to 1800s saw them hunted almost to extinction, but a recent resurgence of research and lobbying by conservationists has seen their numbers climb again. One study estimates global numbers of beavers to be around 10 million – still a far cry from times when they numbered 100 million in North America alone.
Beavers are best known for their skill at building dams in rivers. These dams create wetlands and standing ponds. In turn these wetlands and ponds contribute to better stream quality, which leads to healthier fish populations, carbon capture via the shallow ponds, which hold back silt and sequester the gas, increased resistance to wildfires, and provide a habitat for other animals. All this contributes to the beavers’ status as a “keystone” species, essentially defined as an animal that multiple other species rely on, within an ecosystem.
While the beaver dams are being constructed in Utah and Northern California, in the Danube Delta of Central Europe, another kind of dam is being removed to clear the way for beavers.
In late 2019, 10 dams and other manmade structures were removed on the Kogilnik, Kagach and Sarata Rivers, in the upper part of the Sasyk lagoon of the Danube Biosphere Reserve in Ukraine. The project was designed to restore rivers to their former free-flowing state and, hopefully encourage the return of the beaver. The effort appears to have worked. In March this year, a reserve employee found a large number of felled willow trees – one of the species beavers love to gnaw on. He followed the trail of these gnawed trees to discover a beaver’s dam.
The beavers along the Danube may have returned of their own accord but, in other areas of Europe, people have taken a more active approach to reintroduce them to the landscape.
After 400 years of absence, beavers are being reintroduced to counties across the U.K., from Scotland all the way down to Devon. There is particular interest in how beaver dams can decrease the impacts of floods: Experts expect a reduction of up to 60%, as the structures the beavers build, reduce the water flow.
Around 200 wild beavers were discovered on the River Tay in Scotland back in 2001, and since then, scientists have been scrambling to conduct controlled releases throughout the U.K. to study their impact on the environment.
In 2008, a family of beavers was found on the River Otter in East Devon – the first time in 400 years beavers had been spotted in England. When that family gave birth to kits in 2014, the local authorities initially planned to remove them from the river, considering them an invasive species. However, pressure from conservation groups persuaded the government to allow scientists to turn the site into a five-year experiment to monitor the beavers’ effects on the landscape.
The results showed the beavers created 13 ponds along a 183m (600ft) stretch of stream, storing well over 1,000 tons of water. The ponds trapped 15 tons of carbon and one ton of nitrogen – a fertilizer that, in excess, is detrimental to water quality. The water entering the site was heavily polluted with runoff, washed into the stream from farm fields during heavy rains, but the network of dams acted as a filter, cleaning the water.
At the end of the trial, scientists found fish populations were 37% higher in beaver ponds than elsewhere along the river. During flooding events, peak water flows were lower along dammed areas, and other wildlife, including teals and water voles, were doing better than before the trial. The dams slowed the flow of water, significantly reduced the impact of flooding downstream. In addition, the ponds held water, so the stream kept flowing, even when it hadn’t rained for weeks.
Beaver releases are now happening in England and Wales, as well as in Utah, Idaho, and on Indian Reservations in California, Washington and Oregon, the return of the beaver to the world’s stage seems set.
