Beavers are semi-aquatic rodents. There are two species – the Eurasian and the North American which cannot interbreed but display similar characteristics and behaviours. They are excellent swimmers and divers, can swim underwater for ½ mile, and hold their breath for up to 15 minutes. Beavers are best known for their natural trait of building dams in rivers and streams, and building their homes (known as beaver lodges)by the resulting pond. They are the second-largest rodent in the world.
Beavers always work at night carrying mud and stones with their fore-paws and timber between their teeth. The largest known dam was discovered by satellite imagery in Northern Alberta in 2007, approximately 850 meters (2,790ft) long. Dam building is extremely beneficial in restoring wetlands and providing habitat for many rare and common species.
The ponds created by well-maintained dams help protect the entrance of the beavers’ lodge from predators. The lodge is also created from severed branches and mud. The beavers cover their lodges with fresh mud every autumn, which freezes when the frost sets in. The mud becomes almost as hard as stone. The lodge has underwater entrances to make entry nearly impossible for any other animal. Contrary to popular belief, beavers create the entrance after they finish building the dam and lodge structure. There are typically two chambers within the lodge, one for drying off after exiting the water, and another, drier one where the family actually lives.
Beavers usually live in family groups. As many as 12 beavers may make up a family, but generally there are 6 or fewer. The group includes the adult male and female, the young born the year before, and the newborn. A female beaver carries her young inside her body for about three months before they are born. She has two to four babies at a time. Most young beavers, called kits or pups, are born in April or May. Beavers live as long as 12 years.
Beavers eat the inner bark, twigs, leaves, and roots of trees and shrubs. Poplar trees, especially aspens, cottonwoods, and willow trees are among their favorites. They also eat water plants, and especially like the roots and tender sprouts of water lilies. Beavers store food for winter use. They anchor branches and logs in a cache under the water near their lodges. In winter, they swim under the ice and eat the bark.
Campaign to Save the Tay Beavers
The Ramsays at Bamff were active in the campaign for the Tay Beavers – a population of wild beavers in the catchment of the Tay originating from escapes from enclosures in various parts of the catchment. They were first spotted in 2001. The official estimate in Nov 2012 was 145 and in 2018 a second survey estimated that the number had grown to 450.
The charity that was formed in the course of the campaign – Scottish Wild Beaver Group – works with the Scottish Beaver Forum, the stakeholder committee chaired by SNH which brings together the various organisation with an interest in beavers in Scotland. On 1st May 2019 beavers were given European Protected Status under Scottish law.