Beaver inhabit rivers, lakes, ponds, marshes, and low-gradient streams, especially those with plentiful trees and shrubs that they can eat and use for dam building.

You might think they wouldn't like to live in urban streams, but the fact is that urban streams often provide ideal habitat for beaver because most streams in cities are low gradient (meaning they have more level stream beds and slower moving water) and there are often ideal narrow sections of streams such as at road crossing, that make building and maintaining a dam easy. From a beaver's perspective, roads are large manmade dams with tiny holes in them called culverts. It's no wonder that undersized culverts are often the first place beaver will build their dams.

Beaver are vegetarians. They eat primarily the cambium of trees (the layer just below the bark), and leaves and twigs from trees and shrubs. They also eat aquatic vegetation, grasses, rushes, sedges, and forbs. Like most herbivores, beaver forage from a broad range of vegetation, selecting different plants during different times of year.

When it comes to trees and shrubs, beaver prefer to eat native species like willow, black cottonwood, Oregon ash, red-osier dogwood, and bigleaf maple. They will also forage on ornamental vegetation and some crop plants if there are not enough of their preferred native species present.

A beaver colony, or family, may include anywhere from two to twelve individuals at any given time. Each colony includes a breeding pair and their offspring from the current year and the previous year. Beaver reproduce only once a year in the spring, and each litter consists of anywhere from one to eight offspring, called kits. Beaver family units are highly territorial and will keep other beaver from moving into their habitat. Offspring leave the family around two years old to seek out their own territories.

Beaver are fast and agile in the water, but slow and vulnerable on land. It is for this reason that you will rarely see beaver venture far from the water's edge, and why beaver build dams and canals. Beaver dams create deep water for protection from predators, access to food supplies, and safe underwater entrances to dens. Often referred to as "nature's engineers," beaver are the only animal besides humans that so significantly alter the landscape to suit their own needs and desires.

Beaver typically build their dams in low lying areas with shallow, moving water during months when rainfall and stream flows are lowest. The sound and feel of flowing water seem to stimulate beaver to build or patch dams. They will utilize natural or manmade objects, such as a stone wall, culvert, natural constriction in the streambed, tree stump, etc. to anchor their dams. Once built, beaver maintain their dams to sustain water levels so that they do not have to travel far on land to gain access to forage and materials to maintain their dam.

No. In areas with plenty of available deep water (like the Willamette River) and adequate forage opportunities, there is no need for dam building. In this instance, beaver will simply dig a den in a high bank or build a lodge if digging a bank den is not feasible.