Keystone Species

A keystone species is an animal whose actions shape its ecosystem to the benefit of other species too. Without its keystone species, an ecosystem might not survive. Examples include:

• The beaver, above, which builds dams that create wetlands.
• The prairie dog, whose vast networks of burrows provide habitat for other animals also.
• The wolf, which keeps deer and elk populations in check, which in turn prevents overgrazing of woodlands.