Busy beavers making a comeback

RODENT lovers are over the moon – beavers are breeding again in Scotland.

Three families from Norway were released into lochs at Knapdale Forest in Kintyre last year. Now, two of the families have at least one new cub each. Captive beavers have bred elsewhere in Britain but these are the first wild ones to be born there in almost five hundred years. The species was last seen in 1527.

The beaver, one of the world’s most remarkable animals, is the largest rodent in Europe and the second largest in the world. This chubby overweight relative of the guinea-pig has prominent whiskers and a paddle-shaped tail. The swimming-aid doubles as a warning device: parents alert the family to danger by slapping the water surface.

This rodent’s hydro-engineering skills are legendary. The dams and river channels it makes are the animal equivalents of Dutch dykes. They stem the flow of water, creating deep pools in which beavers construct lodges, island mounds of stones mud and vegetation.

Birds, bees and spiders are renowned for their constructions. Nests honeycombs and webs, however, are instinctively created rather than planned. Move a strand of a web, while it’s under construction, and the spider won’t spot the error; it will continue building even though the resulting web becomes a total mess. Beavers, however, take account of local geography and water fluctuations. Their dams and channels vary so much in design that the builders must have at least a crude plan of the final structure in their heads when they start work. Dams in Europe may be up to 150 metres long.

The snug den inside the beaver mound, with its underwater entrance, is the perfect defence against hungry wolves and bears. Kittens, born and raised in the chamber, remain close to their birthplace for two years. Family groups will, therefore, have both one- and two-year-old youngsters.

Grasses, leaves and twigs are the mainstay of the diet; underwater stores support the family through the winter. Vegetation decays very slowly in cold wet conditions; caches are virtual refrigerators and the family can survive even if the river freezes over for weeks.

The story of the beaver in Europe is not a happy one. Coats made from their fur were fashionable with the great and the good until recently.

The animal’s scent glands contain an aromatic oil called castoreum, once thought to have medicinal properties. Widely used in making perfumes, the contents of a single animal’s glands could cost the equivalent of a worker’s monthly wage. The demand for skins and oil led to hunting pressure and populations everywhere were decimated. Beavers, once common throughout the continent, managed to survive only in a few remote locations of Scandinavia, eastern Germany and Russia. The last English and Welsh ones were killed in the 12th Century. There’s no evidence that the species was ever in Ireland.

The remains of ancient beaver dams can be seen in the Swedish landscape, but the rodent was rendered extinct in 1871.

Re-introductions from Norway proved highly successful; there are now about 100,000 beavers in Sweden. A similar experiment in France restored the species to tributaries of the Loire. Releasing Canadian beavers in Finland was not a good idea; the foreigners now outnumber the natives by 30 to one.

If all goes well in Kintyre, introductions are envisaged for England and Wales. The proposal, however, is not to everyone’s liking. Foresters worry about the destruction of trees. Beavers don’t eat fish, but their dams alter water levels. These increase the flooding risk on low-lying farmland and paths along river banks can be inundated. Beaver defenders, however, claim that, by slowing water flow with their dams, the animals improve the holding capacity of rivers and so reduce the flooding risk.

The enthusiasts also maintain the rodents add to biodiversity, increasing the range and numbers of invertebrate and fish species.