One study found that 68 percent of the beaver colonies recorded in Colorado were in valleys with a stream gradient of less than 6 percent. No beaver colonies were recorded in streams with a gradient of 15 percent or more. Marshes, ponds, and lakes are often occupied by beavers when an adequate supply of food is available. The lodge is the major source of escape, resting, thermal, and reproductive cover for beavers. Lodges may be surrounded by water or constructed against a bank.
Beavers are herbivores.
Beavers appear to prefer herbaceous vegetation over woody vegetation during all seasons if it is available. Woody vegetation may be consumed during any season, although its highest utilization occurs from late fall through early spring when herbaceous vegetation is not available. Winter is a critical period, especially for colonies on streams because they must subsist solely on their winter food caches. One study reported that trees of all size classes were felled close to the water's edge, while only smaller diameter trees were felled farther from the shore. Beavers have few natural predators.