Design a Shelter

Just like humans, all animals need food, water, space, and shelter to survive. An animal’s shelter or home protects it from weather and predators, and provides it with a safe place to raise its young, to hibernate, or to store food. Each species builds a shelter that is architecturally designed for its special needs. By looking at an animal’s shelter, one can learn a lot about that creature’s needs and behaviour.

Unlike humans, animals can’t use tools or machines for house construction. Instead, they have built-in tools like sharp teeth, beaks, claws, or feet that can manipulate natural building materials such as grass, twigs, mud, bark, or fur. Animals have developed some amazing solutions to the problems of insulation, heat, drain- age, ventilation, and waterproofing. Some native cultures have learned to survive by observing animal shelters and behaviours. For instance, humans have learned to build igloos or quinzhee shelters in snowy landscapes by observing animals that burrow into snow to keep warm.

The beaver is truly a wild construction engineer that routinely rearranges its environment to create the perfect shelter. The beaver uses vegetation for both food and building materials. Its most important tool is its large, curved front incisors. With this built-in axe or saw, a beaver can chisel through trees up to 1.2 metres in diameter. Like our hands, a beaver’s front paws can hold and manipulate objects.

Once a suitable lake, river, or stream has been chosen, the beaver constructs a dam to slow the water flow and control its depth. As deeper water won’t freeze solid in winter, the beaver can remain active year-round. If the water gets too deep, nature’s little engineer will open the dam to lower the water level. Construction begins when the beaver piles brush, branches, and logs across running water. Green wood is used because it is heavier than dry wood and does not float. The ends of branches are jammed into the muddy bottom so they face upstream. That way, the current keeps the wood in place. Gaps and holes are then filled with more wood, mud, and even rocks.

Upstream from the dam, the beaver builds its lodge on an island of branches piled together, or against an embankment. In both cases, logs and branches are piled to form the base until it rises out of the water approximately 15 cm. A firm platform is constructed with more twigs, bark, and mud. Then, a dome is woven from the branches or stems sticking out from the pile. The top of the lodge is usually thinner and composed of looser branches to increase ventilation. One or two entrances are built under water, enabling the beaver to drag branches inside its lodge for food. The interior of the lodge is divided into a central chamber, a winter food cache, and a bathroom area.

When finished, the lodge is usually two to three metres high, and two to six metres wide. It takes about a month to finish a home, which will be used for many years. It may not seem cosy to us, but a beaver lodge can stay well above freezing, even when it’s very cold outside.