Hunting big game typically requires a "tag" for each animal harvested. Tags must be purchased in addition to the hunting license, and the number of tags issued to an individual is typically limited. In cases where there are more prospective hunters than the quota for that species, tags are usually assigned by lottery. Tags may be further restricted to a specific area, or wildlife management unit. Hunting migratory waterfowl requires a duck stamp from the Fish and Wildlife Service in addition to the appropriate state hunting license.