Beaver

Beavers (genus Castor) are large semiaquatic rodents that live in the Northern Hemisphere. There are two types: the North American beaver (Castor canadensis) and the Eurasian beaver (C. fiber). They are the second-largest living rodents, after capybaras, and can weigh up to 50 kg (110 lb). Beavers have strong bodies with big heads, long chisel-like incisors, brown or gray fur, hand-like front feet, webbed back feet, and flat, scaly tails.

Beavers are found in many freshwater habitats such as rivers, streams, lakes, and ponds. They eat tree bark, aquatic plants, grasses, and sedges. Beavers are famous for building dams and lodges using tree branches, plants, rocks, and mud. They cut down trees to use as building materials. These dams slow water flow and create ponds, while lodges act as homes. Their building creates wetlands that help many other animals, making beavers important to the ecosystem. They live together in monogamous pairs with their young, who help repair dams and lodges.

In the past, beavers were hunted for their fur, meat, and a special liquid called castoreum, which was used in medicine, perfume, and food flavoring. Their fur was very valuable and drove the fur trade. Sadly, overhunting almost made them disappear, but their numbers have grown again since protections began. Today, beavers are doing well and are considered least concern by the IUCN Red List. In many cultures, beavers are symbols of hard work, especially because of their building skills. They are even the national animal of Canada.

Etymology

The word beaver comes from an old Old English word, beofor or befor. This is related to the German word biber and the Dutch word bever. The original root of the word comes from an ancient Indo-European language and means "brown." Words similar to beaver have inspired many place names in Europe, such as Beverley, Bièvres, and Biberbach. The scientific name for beavers, Castor, comes from the Greek word kástōr, which also means "beaver."

Taxonomy

Carl Linnaeus named the genus Castor and gave the Eurasian species the name fiber. German scientist Heinrich Kuhl named the North American species C. canadensis in 1820. For many years, scientists thought these were the same animal until tests in the 1970s showed they are different. The Eurasian beaver has 48 tiny body parts called chromosomes, while the North American beaver has 40, so they cannot mix their genes.

Today, there are two types of beavers: the North American beaver (Castor canadensis) and the Eurasian beaver (C. fiber). The Eurasian beaver is a bit longer with a pointier skull, triangle-shaped nose areas, lighter fur, and a narrower tail compared to the North American beaver.

Characteristics

Beavers are the second-largest living rodents, after capybaras. They can weigh up to 50 kg (110 lb). Their bodies are built strongly, which helps them pull heavy loads.

Beavers have large teeth that keep growing throughout their lives. They also have special features that help them stay safe and comfortable in water. Their fur is very thick and helps keep them warm and dry. Beavers can swim well and use their webbed hind feet to move through the water. Their tails help them balance, steer while swimming, and store extra food for winter.

Distribution and status

The IUCN Red List of mammals considers both types of beavers to be safe. The North American beaver lives in most of the United States and Canada and can also be found in northern Mexico. This type of beaver was brought to Finland in 1937 and later spread to northwestern Russia and Tierra del Fuego, Patagonia in 1946. By 2019, the North American beavers in Finland were moving closer to where the Eurasian beavers live.

Historically, many North American beavers were caught for their fur, which almost made them disappear. But with protections, their numbers grew to about 6–12 million by the late 20th century, though this is still much less than the original 60–400 million. The introduced group in Tierra del Fuego is thought to be about 35,000–50,000 as of 2016.

The Eurasian beaver used to live across much of Europe and Asia but was greatly reduced by hunting by the early 1900s. In Europe, they were left in small groups in places like the Rhône in France, the Elbe in Germany, and other areas. Thanks to conservation efforts and reintroductions, beavers have returned to many parts of Europe, western Russia, and the Scandinavian Peninsula. Since 2009, beavers have also been brought back to parts of Great Britain. By 2020, the Eurasian beaver population in Europe was over one million. There are also small groups in Mongolia and northwestern China, with estimates of 150 and 700 beavers respectively in 2016. Under New Zealand's Hazardous Substances and New Organisms Act 1996, beavers are not allowed to be brought into the country.

Ecology

Beavers live in freshwater places like rivers, streams, lakes, and ponds. They love water because it helps them hide from animals that might want to hurt them and makes it easier to carry things. Beavers like calm, slow-moving water and usually pick spots with trees nearby for food and building.

Beavers eat plants, mostly leaves and grasses in spring and summer, and tree bark in fall and winter. They build dams from trees and branches to create ponds where they can live safely. These dams change the land around them, helping create wet areas that many other animals need to survive. Their homes, called lodges, are made from sticks and mud, with special doors underwater to keep them safe.

Behavior

Beavers are mostly active at night and during dawn or dusk, staying in their shelters during the day. In the winter, especially in northern areas, they don’t follow the usual day-night pattern and can stay active for up to 29 hours straight. They don’t hibernate and spend a lot of time in their homes, called lodges.

Beaver families are made up of a male and female pair and their babies. These families can have up to ten members and need more than one lodge sometimes. They stay close by grooming each other and playing, and they rarely fight. When a beaver loses its partner, it will wait for a new one. Babies, called kits, are born in the spring or summer after about three to four months. They can open their eyes soon after birth and have fur right away. The mother takes care of them, while the father looks after the area. Older siblings help too. Kits stay in the lodge for the first couple of months, drinking milk but also eating solid food brought by their parents. As they grow, they start exploring outside and eating on their own. After about a year, young beavers help build with their family. They become fully grown around 1.5 to 3 years old and leave home at two years, though sometimes they stay longer if there isn’t enough food or if there are too many beavers in the area.

Interactions with humans

Beavers can sometimes cause problems for people by damaging crops, trees, roads, and gardens. They build dams that can flood areas. In rare cases, they might bite people or pets if they feel threatened, especially if they are sick.

People have many ways to deal with beavers. Special pipes can help manage flooding, and fences can protect trees. Sometimes, beavers need to be moved or their dams removed. Hunting and trapping are also used to control beaver populations. Some places even work to include beavers in parks and green spaces.

Beavers have been important for a long time, especially for their fur, which was valuable in trade. They have also been used in stories and symbols, often representing hard work and nature.