Big Branch Marsh NWR was established in 1994. The Refuge wetlands support fresh water and marine fish, shore birds, wading birds, neotropical song birds, and 17 species of migratory waterfowl. The pine savannah supports the endangered Red-cockaded Woodpecker and an abundance of waterfowl, raptors, wading birds, shorebirds, and alligators. The Refuge was one of the first partners to join the Gulf Coast Phenology Trail in 2016 and includes the Bog and Azalea Trails at the Holy Redeemer Unit. Gulf Coast Phenology Trail core plants include red maple, yaupon holly, red bay, and wax myrtle. Additional species are Chinese tallow, American beauty berry, southern magnolia, and black cherry. Monarch and Gulf fritillary butterflies are also observed. Citizen scientists, who include refuge volunteers, retirees and students, use Nature's Notebook for phenology observation, giving them the opportunity to be outdoors.