U.S. Fish & Wildlife Service -
Wichita Mountains National Wildlife Refuge
Site excerpt: Established in 1901, Wichita Mountains National Wildlife Refuge is one of more than 567 refuges throughout the United States managed by the U.S. Fish & Wildlife Service. The 59,020 acre Refuge hosts a rare piece of the past - a remnant mixed grass prairie, an island where the natural grasslands escaped destruction because the rocks underfoot defeated the plow.
Volunteer.gov
Opportunities to volunteer throughout the government
U.S. Fish & Wildlife Volunteer Website
What volunteers are doing throughout the system
National Wildlife Refuge Association
Non-profit support program for Refuges and Friends groups