Beavers on the rampage

Beavers: Lords of the rivers

Timber!

A beaver will only fell a tree for a particular reason - be it a larger mature tree to form a dam, or a young tree for food. They are herbivores and eat mainly leaves, bark and twigs, as well as aquatic plants. A single beaver needs just five minutes to fell an 8-foot (2.4-meter) tree.

Beavers: Lords of the rivers

Ready for the elements

Beavers have their own kind of swimming goggles, in the form of a set of transparent eyelids that enable them to see underwater. There are two species of beaver: the European beaver and the North American beaver. Although they look and behave similarly, they are not genetically compatible.

Beavers: Lords of the rivers

Formidable swimmers

Beavers use their broad tails like rudders to steer underwater, and can swim at speeds of up to 5 miles per hour (8 kilometers per hour). They also use their tails to slap the water as a warning of danger, or as a warning signal to alert others to keep away. Beavers can remain underwater for 15 minutes without surfacing.

Beavers: Lords of the rivers

Home sweet home

Beaver homes are called lodges, and are built in the form of domes made of branches and mud. They are located in open water for protection from predators, and have underwater entrance holes. Beavers are active throughout winter and use their ponds even when they are covered with ice.

Beavers: Lords of the rivers

Good houseguests

Beaver lodges usually contain two dens, one for drying off after entering the lodge underwater, along with a second, dryer den where the family will live and socialize. There are usually between two and 12 beavers in a colony, and three baby beavers, or kits, born per litter to a beaver couple each year.

Beavers: Lords of the rivers

Stemming the flow

Beavers create their dams - large log, branch, and mud structures - to block streams, turning fields and forests into the large ponds they love. Beaver dams can be vast - the largest is in Wood Buffalo National Park, Alberta, Canada - it stretches for 850 meters, and is visible from space.

Beavers: Lords of the rivers

Regulating ecosystems

It is this ability to transform the landscape that causes particularly farmers to consider them as pests: beaver dams can cause floods and block irrigation. They also fell trees that humans might want to leave standing. But beavers play an important role in ecosystems, helping to regulate water flows and humidifying the land.

Beavers were almost completely wiped out of Germany by the early 20th century. Now, they've made a comeback. But their busy construction work is causing tensions with human neighbors.

Few animals create such impressive structures or alter their environment so dramatically as the beaver. Few, except for humankind.

Nature and Environment | 07.04.2017

"Beavers are like the architects of our waterways," says of Iris Barthel of German conservation group Nabu. "They build dams, burrow, gnaw and fell trees and shrubs. In this way, beavers have shaped our riverscapes for millions of years."

But despite - and sometimes because of - a shared propensity for reshaping the landscape, humans and beavers don’t always make good neighbors.

By the early 20th century, humans had hunted the Eurasian beaver - prized for its meat and warm, dense pelt - almost to extinction. In Germany, a few animals survived in pockets on the Elbe river.

Environment | 19.12.2014

More recently, protection of the species and reintroduction programs have seen beaver numbers bounce back. Today there are around 30,000 in Germany, with strongholds in east Germany, as well as parts of Bavaria, on the Upper Rhine and the southwest of North-Rhine Westphalia.

After a long absence, the hefty rodents - with their unmistakable flat tails and blunt snouts . became, if not a common sight, at least something you might be lucky enough to glimpse on a German riverbank.

Still, beavers are shy, and anyone looking for signs of their presence along the Rhine or Elbe might do better to look out for a beaver's dam, or the stumps of trees felled by gnawing.

Beaver dams are hard to miss

Beaver-made flooding

Some riverside residents, however, don't have to go out looking for traces of beaver activity. Just as manmade dams can be disaster for the habitat of other animals, so some Germans have found their own homes flooded by beaver-made reservoirs.

One homeowner who found the foundations of his house in German city of Jülich threatened by rising water levels from a beaver dam told local broadcaster Westdeutscher Rundfunk: "They don’t belong here in the middle of the city. We’re not an open-air zoo."

Nabu says conflict usually occurs when farms or gardens extend right up to the river bank or where the natural floodplain is altered.

"The beavers aren’t aware of property ownership. They see the riverbank as a place they can dig their burrow," says Barthel. "They see tasty food in fields or orchards. So it can happen that a tractor breaks a beaver lodge or a beaver fells a favorite apple tree."

She adds that beavers have been accused of burrowing into dams and dikes, disrupting manmade flood defences, but says there are well-practiced defenses against this kind of damage.

"If beavers are pilloried by politicians, it’s primarily to distract from their own failures in flood prevention," says Barthel.

Beavers are landscape architects - something humans hold against them

Warming beaver-human relations

Biologist Jessica Dieckmann told DW that part of her role as newly-appointed commissioner on beavers for the German city of Hamm was to help deal with conflicts arising between homeowners and their beaver neighbors.

She explained that because injuring or killing beavers or damaging their dams and burrows is forbidden in German, “a solution has to be found tactfully.”

"A solution could be that landowners sell a 20-meter-wide (66-foot-wide) riparian strip and make it available for nature protection," says Dieckmann.

Her other tasks as beaver commissioner include finding out whereabouts beavers are in Hamm and how many there are, to know how best to deal with the creatures in the future.

Beavers usually live in burrows in the river bank accessed by an underwater tunnel. The dam ensures the water is deep enough to hide the entrance to their "lodge" beneath the surface.

But while human construction often runs at complete odds with the needs of other living species, beaver dams bring benefits to a whole host of other species.

"They create small ponds, deadwood, marsh areas or open up areas of soil," says Barthel. These provide habitats for dragonflies, amphibians and reptiles, for fish and birds. "Where humans have to spend a lot of money on preserving biodiversity, the beaver helps out for free."

"At the same time, it contributes to the cleanliness of water, re-natures rivers and supports natural flood prevention."