These animals can stay under water for as long as 15 minutes because of their specially adapted lungs. Beavers have wide, hairless, flat tails. Their tails are not only used for steering but also for balance, warning signals, and fat storage. When beavers chew on trees they use their tail like a kick stand to give them support. When a beaver feels threatened by danger it will slap its tail on the water as a warning to the predator.
Beavers also store fat in their tails for the long, cold winters.
Beaver dams and lodges are two easily identifiable clues of beaver activity. Another clue is to look at the trees along the shoreline to see any signs of gnawed trees. Beavers have a dramatic effect on the land. The dams they create provide new habitat for fish, plants, otters, and other underwater creatures. The new ponds also provide new water sources for moose and wolves.