The Cause There doesn't seem to be a single answer to explain the cause of this phenomenal snow goose population growth.
Much evidence suggests changes in winter food availability is a primary factor.
Historically, snow geese migrated across extensive grasslands and wintered in coastal marshes where they fed on roots and tubers of aquatic plants. This food source has increased overwinter survival and possibly even productivity. Other factors may also be involved. Changes in long-term weather patterns in the arctic have been correlated with increases in production. Humans have provided countless refuges and management areas where migratory birds can feed and rest all across the continent.