Beavers have a great passion for dams and thanks to their strong front teeth they are able to gnaw through tree branches to build ingenious current-proof and climate change-proof works. But why do they do it?
Safety ZoneLet’s start from the beginning. Beavers are semiaquatic rodents that live on the banks of rivers, streams, lakes and ponds throughout Europe and North America. Being destined for this habitat, their instinct to build dams allows them to “stay safe”, although it is particularly demanding considering the shape of their body and their legs, which are really short but very skilled at manipulating objects and digging. When on land, they are very clumsy and vulnerable. But when they are in the water, they are almost invincible because they are excellent swimmers and can hold their breath for up to 15 minutes. Thus, by building a dam, they create a deep enough water shelter in which to hide, a sort of “comfort zone” in which to relax away from predators.
Fort on the waterWhat we may not know is that to create their aquatic refuge they don’t only use tree trunks and branches, but also bark, leaves and aquatic plants such as water lilies. In short, everything they find in their habitat within reach. In addition, beavers dig vast networks of canals behind their dams to spread the water, creating escape routes for them to safely reach trees to obtain and hide food. But while dams protect beavers, they don’t dwell within these structures. The beaver families indeed live in a mud, grass and moss den that is located on the shore of the aquatic shelter but with an underwater entrance.
Green oasisThanks to their dams that slow down the water, much of it is stored in the ground, where plant roots can access it even in times of drought. This helps keep the vegetation thriving, creating a fire-proof den. In addition, the scientists observed that the vegetation around beaver dams extracts significantly more greenhouse gases from the air and reduces flood damage. All this means that beavers are not only more likely to survive climate change, but play a valuable role in protecting the environment. That’s why beavers are called ecosystem engineers and are a key species due to the great positive impact they have on the landscape and biodiversity of an area.
Iron teethAs we have said, beavers have very strong and robust teeth. And if their enamel is yellow, almost orange, it is because it contains particles of iron which also protects them from acid attacks and tooth decay. When chewing on a tree, beavers start biting from the left side and work their way up to the right. Tree branches are cut and carried to their destination with the powerful jaw and neck muscles. Other building materials, such as mud and rocks, are held by the forelimbs and tucked between the chin and chest. But despite hard work, beavers’ teeth don’t wear down like ours because they’re constantly growing, which allows them to chew indefinitely (or at least for their average ten years of life).
Waterproof hearingBut what drives a beaver’s instinct? Years of evolution have led this species to perfect the engineering techniques, which are handed down from parents to children, which they also use airflow and temperature to adapt their architecture. But it seems that their hearing activates their “sensor”: every time they hear water flowing, they start a dam to “limit” the leaks. Indeed, a study has shown that if they hear a loudspeaker playing the sound of running water, a beaver will activate to build a dam over it, even if there is actually no water. But the activation mechanism is a little more complex than that, and remains a mystery, since it seems that every beaver also knows its limits and does not start a work unless it is able to complete it.