Modern beavers are renowned for their ability to chew through tree trunks to build their dams and lodges, creating ponds to live in and providing protection from predators and a place to store food.
You might assume that the giant beavers that lived in prehistoric times were also adept at gnawing down trees, thanks to the incredible size of their bodies (between six and seven feet long) and their teeth (six inches). Yet it seems that the members of the genus Castoroides, which lived across much of North America during the Pleistocene epoch, did surprisingly little logging. That might be part of the reason why they died out around 10,000 years ago, while modern beavers (which likely coexisted with Castoroides) survived.
From studying giant beaver bones and teeth found near Old Crow, Yukon, paleontologists at Western University in Ontario, Canada, found that giant beavers ate a diet consisting almost entirely of aquatic plants and didn’t gnaw much on trees. Today’s beavers are generalists that eat a varied mixture of plants, including leaves, roots, ferns, grasses, sedges, and water lilies. Notably, they also eat the bark and cambium of various tree and shrub species.
The dependence of Castoroides on wetland habitats made these giant rodents susceptible to a changing climate, which is exactly what happened at the end of the last ice age, when warmer, drier conditions became the norm. Unlike modern beavers, which are amazingly adept at creating their own ponds, ensuring they always have a safe home and aquatic plants to eat, their giant prehistoric relatives may have simply run out of their favorite food—and their homes.
Gnaw on these facts about (modern) beavers:
- After the capybara, the beaver is the second-largest living rodent. Beavers can weigh up to 110 pounds (50 kg).
- Beavers have long been hunted for their warm, luxurious, water-resistant fur, and it’s not hard to see why. Their coats have around 100,000 hairs per square inch. The North American beaver population was almost hunted to extinction by the end of the 19th century, though it has since rebounded due to the decline of the fur trade and protections against trapping; nevertheless, it is still a fraction of what it was in the precolonial era.
- Beavers are considered a keystone species due to their significant impact on the biodiversity of the territories where they live. They are also ecosystem engineers because of the effects that their dam-building has on the environment. By creating ponds and wetlands, they allow aquatic plants to grow in new areas, which are then colonized by insects, birds, amphibians, fish, and other mammals.
