The danger of extinction now seems remote, after the depredations of the 19th century which were halted by legislation. In 1600 there were 60 to 100 million beaver in North America. Whitemen exported 50,000 skins annually until, by 1800, the beaver was extinct east of the Mississippi. Legislation has protected the beaver and today 175,000 pelts are harvested annually. In some places the beaver has re-established itself to nuisance proportions.
Beavers are active usually in morning and evening.
Their main activities are cutting trees for building or repairing lodges and dams, or for winter food. They use their upper incisors to cut a ring around the trunk at the height of their mouth when standing on their hind feet and tail. They sink their lower incisors into the trunk below the ring and lever out a large chip. Trees are trimmed and either dragged to the building site, cut into logs or even floated in a canal dug by the beaver. The site for a lodge must be in water deep enough to provide room for storage of food and to keep the entrances under water.