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.

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.