Nearly 40% of mammal species are rodents, and they are found on every continent except Antarctica. Rodents include mice, rats, squirrels, chipmunks and beavers, among others.
Why do beavers build dams?
Environmentalists agree that beaver dams help the environment by creating wetlands but why are some landowners and farm owners getting riled up? How could these dams be hazardous to roads, bridges and levees?