Restoration

Not long ago the beaver was absent from the state. In fact, it was absent from the late 1700s to the early 1900s. Intensive unregulated hunting and trapping, combined with deforestation to clear land for agriculture, led to the disappearance of beaver habitat and the beaver. 

In the early 1900's, forested habitat started to recover when many farmers abandoned their farms in order to take jobs in cities or to start new farms in the more fertile Midwestern United States. With the forests able to retake the landscape, the beaver was able to return. 

In 1928, beavers were found in West Stockbridge. This was the first recorded occurrence of beaver in the state since 1750! The return of beaver was greeted with enthusiasm by the public and efforts to restore a beaver population were undertaken. Specific actions taken included the acquisition of three additional beaver from New York which were released in Lenox in 1932. 

In 1946 there were some 300 beavers in 45 colonies all located west of the Connecticut River. By 1951 the beaver population was such that the legislature authorized the establishment of a beaver trapping season. Consequently, in 1952 regulations were put in place to allow the regulated harvest of beaver. The regulations were designed conservatively to insure the perpetuation and continued growth of the beaver population.

Habitat

Our forests continue to provide excellent beaver habitat, and by now beavers have been fully restored to the Commonwealth. Beavers are both common and abundant throughout most of Massachusetts. They are still uncommon in southeastern Massachusetts, and absent from Cape Cod and the islands.

Beavers are semi-aquatic mammals spending approximately 80% of their time in water. They are unique among mammals in that they alter their habitat to meet their needs, primarily by damming up small rivers and streams to form ponds. These ponds allow beavers to have access to food, protection from terrestrial predators, and shelter in winter. 

Dams are structures built out of sticks and mud, with the base of the dam consisting of mud and stones. Beavers are constantly on the look-out for leaks or breaches in the dam; they are tipped off by the sound of escaping water. 

Lodges, like dams, are also built out of sticks and mud, and are usually built in the deepest part of the newly formed pond. They can be 15-40 feet across at the base and 3-8 feet above the water line. The inside of the lodge is kept clean and provides a warm shelter for the beaver during the winter months. Studies have shown that even if the outside temperature is -40° F, the inside of the lodge remains above freezing. The lodge also provides a secure place for the female to give birth to her kits.

Beavers favor habitats containing shrubs and softwood trees, flat terrain, and perennial streams that can be dammed to create ponds. Beavers are generally associated with rivers, ponds, lakes, and areas that can be converted to beaver ponds. The water must be deep enough to provide suitable aquatic habitat under winter ice.

Offspring

Adult beavers have few predators and may live up to 20 years or more. 

Beavers stay with the same mate for life and breed during winter (January through March). The females give birth to 1-9 kits (4 kits is the average) inside a lodge between April and June. The kits spend most of their time in the lodge, where they can develop and stay relatively safe from predators. 

Within a week of being born, the kits learn to swim, and by three months of age, the kits are weaned. The kits stay with their parents through two winters before dispersing the following spring. A single family unit is called a colony, and is typically made up of 6-8 individuals that consists of two adults, that year's kits, and the young from the previous year. 

Beavers are semi-aquatic mammals spending approximately 80% of their time in water. They are unique among mammals in that they alter their habitat to meet their needs, primarily by damming up small rivers and streams to form ponds. These ponds allow beavers to have access to food, protection from terrestrial predators, and shelter in winter. Dams are structures built out of sticks and mud, with the base of the dam consisting of mud and stones. Beavers are constantly on the look-out for leaks or breaches in the dam; they are tipped off by the sound of escaping water. Lodges, like dams, are also built out of sticks and mud, and are usually built in the deepest part of the newly formed pond. They can be 15-40 feet across at the base and 3-8 feet above the water line. The inside of the lodge is kept clean and provides a warm shelter for the beaver during the winter months. Studies have shown that even if the outside temperature is -40° F, the inside of the lodge remains above freezing. The lodge also provides a secure place for the female to give birth to her kits.

Food

Beavers are strict vegetarians, also known as herbivores. They feed on a variety of aquatic plants (especially water lilies) and the shoots, twigs, leaves, roots, and bark of woody plants. The bark, particularly the inner bark, of trees and shrubs are important foods, especially in winter. Aspen, birch, alder, and willow are favored food plants.

Beneficial Aspects

While many people think about beaver only when they are causing problems, it is important to remember the beneficial aspects of beavers. Beavers have played an active role in New England's ecology for thousands of years. 

Since European settlement, more than half of the wetlands in the lower 48 states have been lost. By damming streams and forming shallow ponds, beavers create wetlands. These wetlands provide habitat for a tremendous diversity of plants, invertebrates, and wildlife, such as deer, bats, otter, herons, waterfowl, songbirds, raptors, salamanders, turtles, frogs, and fish. 

But it is not just wildlife that benefits from beaver-created wetlands; people benefit too. Wetlands control downstream flooding by storing and slowly releasing floodwater. They also improve water quality by removing or transforming excess nutrients, trapping silt, binding and removing toxic chemicals, and removing sediment. Flooded areas can also recharge groundwater.