Keystone Species II – Wolves by Joan Slottow

Since their first introduction in Yellowstone in 1995, wolves have proven to be a keystone species, a species critical to maintaining a healthy environment.  After the last wolves were killed in the Yellowstone region in 1926, woody plants suffered from overgrazing and died off and the whole environment became degraded.  Because wolves kill herbivores such as elk and deer, after their reintroduction, stands of willows, no longer devoured, grew back along the stream banks.  This halted stream erosion and created habitat for the return of birds and beavers.  Scavengers such as ravens, coyotes and bears grew to depend on wolf-killed elk, especially in winter.  Because wolves are now present, other species thrive.