Beaver Dam at Dial Pond, Adirondack, NY.

From "Hiking the Adirondacks" by Lisa Densmore: Few animals have had as much impact on region as the beaver (Castor canadensis) has on the Adirondacks. Easily identified by its black, flat, scaly tail, the beaver is the largest rodent in the park, and they're widespread. Beavers can be found along most waterways here. New York's state mammal, the average beaver is about 40 inches long and weighs about 45 pounds. Historically, they were prized for their fur. Trapping beavers was among the first reasons Europeans ventured into the Adirondacks. In the early 1600s fur traders had decimated the beaver populations elsewhere in the state, so they began to venture into this remote region. By 1900 most of the beavers in the Adirondacks had been trapped as well. In 1903 the state legislature appropriated $500 to bring back the beaver. About fifty were released into the Adirondack Park, and they flourished. Today there are between 50,000 and 75,000 beavers in the Adirondacks. Their dams, lodges, burrows, stumps, and trails leave an unmistakable mark on the landscape. For hikers, these flat-tailed rodents are both a blessing and a curse. They create expansive wetlands that range from open ponds to grassy marshes, which are interesting to observe and break up the monotony of a woodland walk. Yet often they are the cause of flooding, which can lead to problems as minor damp feet or as serious as an impassable trail.