While the Hillsborough River is spring fed, springs are not the major contributor to river flow. The river is primarily a blackwater river. Blackwater streams and rivers originate in swampy areas where organic acids stain the water dark brown like the color of tea.

ecology swamp

Natural Communities

As the Hillsborough River forms in the Green Swamp, its watershed contains river floodplain forests, cypress domes, pine flatwoods and sandhills. Additional natural communities in the watershed include oak hammocks, sawgrass marsh, hardwood swamp, a sphagnum bog and more. It’s the decomposing plant material from these natural communities that stains the river’s water dark brown.

The river’s swamp habitat was once home to ancient cypress trees, which were removed by the logging industry in the 18th, 19th and early 20th centuries, changing the ecology of the habitat.

ecology stump

Wood Stork


The watershed is home to hundreds of animal species and most of these species are common to Florida. Some include wood storks, snowy egrets, blue herons, alligators, snakes, turtles, river otters, bobcats, eagles and more. Click here to view other common species in west-central Florida.

Featured Animal: Wood Storks

Wood storks call the Hillsborough River watershed home. There’s a wood stork rookery at the Lower Hillsborough Wilderness Preserve (LHWP). Do you know what a wood stork is? How about a rookery?

A wood stork is a large, long-legged wading bird. It’s white with a distinctive gray-black, featherless head. The birds hold open their large bills and sweep them side to side as they walk through shallow waters and wetlands catching fish. The moment a wood stork feels a fish against its beak, it closes its beak. This is considered one of the fastest movements in the animal kingdom! Wood storks are considered a threatened species by the U.S. Fish & Wildlife Service.

A rookery is a communal breeding ground for birds that may contain just a few nests or hundreds of nests. While parent birds only care for their nestlings, they may join together to defend their young. Preserving the extensive wetland communities in the watershed will help in the protection of habitat for wood storks in this rookery.