Beavers and their dams are so useful to the environment


Beavers and their dams are so useful to the environment that animals including moose, otters and weasels all benefit from their antics

  • Researchers describe them as ‘ecosystem engineers’ because of their dams
  • The semiaquatic rodents boost biodiversity in a number of different ways 
  • Their dams flood large areas, creating shallow ponds that harbour lots of insects 
  • The trees they fell create open spaces in the forest where young trees can grow 

An array of different animal species benefit from having beavers in their environments because they boost biodiversity, researchers claim. 

The semiaquatic rodents were capable of facilitating many groups of organisms to thrive near beaver patches including moose, otters, and weasels.

According to the study, they do this by preventing drought, carbon sequestration, flood management and keeping streams cool. 

The team, from the University of Helsinki in Finland, describe them as ‘ecosystem engineers’ because their dam-building work has such a good effect on habitats.  

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A selection of different animals benefit from having beavers in their environments because they boost biodiversity, researchers claim. The semiaquatic rodents benefit the environment by preventing drought, carbon sequestration, flood management and keeping streams cool

A selection of different animals benefit from having beavers in their environments because they boost biodiversity, researchers claim. The semiaquatic rodents benefit the environment by preventing drought, carbon sequestration, flood management and keeping streams cool

Both the Eurasian beaver and the American beaver were almost driven extinct by hunting in the early 20th century.

In Britain, beavers became extinct around 400 years ago, mainly because of hunting for their fur and meat. 

The researchers argue that promoting facilitative ecosystem engineering by beavers could be very valuable in habitat conservation or restoration, especially in landscapes deficient in wetlands.

The team set up camera traps and looked at tracks in southern Finland where the American beaver was introduced in the 1950s. 

After analysing the footage they compared the composition of mammal fauna of 10 beaver-modified sites with 10 control sites. 

The tracks showed that moose, otters, weasels and pine martens were more active in beaver patches than other sites.

‘The otter is a species of some concern in Europe, so this may be important from that point of view,’ Petri Nummi at the University of Helsinki, Finland told the New Scientist

They found that water from the dams beavers build flood large areas, creating shallow ponds that harbour lots of invertebrates, like insects and crustaceans, the study said.

A team, from the University of Helsinki in Finland describe them as 'ecosystem engineers' because their dam-building work has such a good effect on habitats. Beavers were hunted and disappeared from Britain around 400 years ago

A team, from the University of Helsinki in Finland describe them as ‘ecosystem engineers’ because their dam-building work has such a good effect on habitats. Beavers were hunted and disappeared from Britain around 400 years ago

The trees they fell create open spaces in the forest where young saplings can grow, they said.

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Felled trees, saplings and aquatic plants can all provide food for moose. 

When beavers leave a pond and their dams break, the previously flooded area is rich in nutrients and can become a meadow. 

In forests where beavers have been introduced in Finland, their presence is linked to increased activity of several species, according to  

Beavers have begun to re-establish themselves in Europe, thanks in part to at least 157 reintroduction projects that have taken place in 24 European countries. 

In Scotland, they were first reintroduced in 2009 as part of a trial, and now enjoy protected status. But their appetite for destruction has led to conflict with some farmers and landowners.

A trial in Devon ends next year, when a decision will be made whether or not to extend it to other parts of England.

The research was published in the journal Global Ecology and Conservation

HOW AND WHY DO BEAVERS BUILD DAMS?

Beavers are found across the northern hemisphere and are among planet’s most skilled builders.

This reputation has earnt them the nickname ‘nature’s engineers’.

They fell trees by gnawing at their trunks and use the resulting sticks to construct dams to stop the movement of water in ponds, lakes, rivers and streams – creating a bodies of water with a low current.

The mammals then use sticks and mud to create a second structure – a large dome-shaped island that can reach as high as ten feet (3m) tall and up to 1,600ft (500m) long.

Each island includes two underwater entrances and a living chamber above water where the animals sleep and shelter.

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Beavers often line the walls of this chamber with dry leaves and plants to insulate it during winter. 

It remains unclear exactly why beavers build dams, but scientists speculate the creatures use it for warmth and shelter in the winter and as protection from predators.

Beavers are strong swimmers, and creating a reservoir of water allows the animals to play to their strengths to escape those higher in the food chain.

The biggest beaver dam ever discovered measured 2,790ft (850m) – more than twice the length of the Hoover dam.

The woodland construction, found in the southern edge of Wood Buffalo National Park in Northern Alberta, Canada, was so expansive it could be seen from space.

 



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