It was a balmy February morning when Lee Martin loaded his gear on a small plane for his monthly flight over Audubon’s Corkscrew Swamp Sanctuary. The goal: determine nesting status and count nests of one of the most unique species that call this region home. With 13,000 acres, Audubon has been protecting Wood Storks and their wetland habitats at Corkscrew for more than a century.
As Research Technician, Martin was excited to check in on the Wood Storks, which historically began nesting in Southwest Florida by the end of December. Unfortunately, as he scanned the trees he didn’t spot any of their signature black and white silhouettes. Rather, from his vantage point 500-ft above the sanctuary, he saw less standing water in the marsh and swamp than he had just a month ago- a good sign since storks rely on falling water levels to improve foraging conditions.
The timing of the rise and fall of water is key to Wood Storks' success in South Florida. Receding water levels concentrate wading bird prey: small fish and crayfish. But too much or too little of a good thing is never good. When wetlands dry completely, the small fish are forced into dry season refuges where they’re often consumed by large fish, alligators, or other predators. But too much water disperses fish across the landscape, spreading them out and making it more difficult for birds to find food. Without consistent access to prey items throughout the breeding season, Wood Storks cannot feed and fledge their young.
Over the past 20 years, water levels at the Sanctuary have been anything but consistent. The research team has determined the changing hydrology is likely due to some combination of increased demand for water across the watershed, water management activities necessitated by flood control, and changes in plant communities that increase evapotranspiration rates.
In the 2018 nesting season, 250 Wood Storks nested at the sanctuary. In 2019, there were only two chicks that fledged. While Wood Storks have been seen foraging in the swamp and some nesting activity has been reported by research partners monitoring colony sites in Everglades National Park, there is still no sign that Wood Storks are nesting at Corkscrew or any other Southwest Florida colonies so far this year.
It isn’t necessarily too late for them to start, but, cautions Martin, if they wait too long, their feeding grounds could become inundated with early summer rains before their chicks successfully fledge. He is anxiously awaiting his next flight, scheduled for the first week in March.
The Wood Storks’ battle for survival is heavily dependent on how we divide this water pie. By reducing water use in the dry season (winter-spring) and advocating loudly for wetland preservation, residents and visitors can help ensure Wood Storks can continue to find the habitat they need at Corkscrew Swamp Sanctuary.