From PBS - The fascinating story of beavers in North America - their history, their near extinction, and their current comeback, as a growing number of scientists, conservationists and grass-roots environmentalists have come to regard beavers as overlooked tools when it comes to reversing the disastrous effects of global warming and world-wide water shortages. Once valued for their fur or hunted as pests, these industrious rodents are seen in a new light through the eyes of this novel assembly of beaver enthusiasts and "employers" who reveal the ways in which the presence of beavers can transform and revive landscapes. Using their skills as natural builders and brilliant hydro-engineers, beavers are being recruited to accomplish everything from re-establishing water sources in bone-dry deserts to supporting whole communities of wildlife drawn to the revitalizing aquatic ecosystems their ponds provide.