Over the past two decades, changes made to the way water flows across the land resulted in water being pulled out of Corkscrew Swamp Sanctuary faster and earlier in the dry season. In this increasingly vulnerable wetland of international significance, nesting birds are paying the price.
Historically, a complete dry-down of the deepest pools along Corkscrew Swamp Sanctuary’s boardwalk occurred only around once every five years. But now, this dry down occurs nearly every year and lasts about two months longer than it once did— spelling bad news for the fish and other animals that birds need wetter conditions to thrive.
As swamp water recedes in the Sanctuary during the dry season, fish, crayfish, and other aquatic prey are concentrated in deep pools, such as the Lettuce Lakes, enticing wading birds to feast on them. Ibis, egrets, and herons crowd the waters first, followed by Roseate Spoonbills and Wood Storks, which seek out these oases when water levels are perfect for their tactile bills to snag fish and other prey easily. The congregation of these birds is a sight to behold, giving Sanctuary visitors amazing opportunities to see and photograph them from the boardwalk until the lakes either dry up or refill from rainfall.
Fish, aquatic insects, snails, worms, and crayfish are adapted to periodic dry downs. In typical years, they survive in the deepest pockets and muddy substrate for short periods until summer rain returns, but many cannot survive when the water table goes below ground for more than a few weeks, as has been the case more frequently in the past two decades.
Some fish species, such as mosquitofish, are capable of quickly swimming long distances to re-populate a wetland, but most of the fish in our system, including sunfish and bowfin, are slow to disperse and need successive years of wet conditions to grow their population and move across the landscape. Each time the Lettuce Lakes dry completely for more than a few weeks, this habitat’s ecological clock is reset, and the aquatic habitat must be repopulated—often by animals in water quite a distance away.
This repopulation takes time, and during this time, the Lettuce Lakes have little food to offer wading birds. At the beginning of the new rainy season, however, shortly after the wetlands refill following a dry down, some animals like crayfish and tadpoles thrive for a few weeks in the absence of fish predators.
Audubon scientists believe the combination of regional wetland loss—tens of thousands of acres over the last 25 years—increased groundwater use, and changes made to the way the water flows across the land led to the relocation of the nesting Wood Stork colony that historically centered around Corkscrew Swamp.
There are other consequences to the lowered water table, including fire. Our changing climate (warmer air temperatures that lead to more evapotranspiration) and changes in rainfall patterns are affecting land managers’ effectiveness in using prescribed fire to reduce fuel loads and protect against catastrophic wildfire.
Luckily, help may be on the way. Since 2018, Audubon has worked closely with the South Florida Water Management District to better understand the problem and seek solutions. The Corkscrew Watershed Initiative, introduced by the District in 2024, includes a public planning process with extensive stakeholder engagement. The initiative aims to identify, evaluate, and prioritize projects to restore historic hydropatterns (the seasonal rise and fall of surface water) in the Sanctuary and other parts of the CREW watershed. Some projects could begin as early as 2026, while other projects will be completed in the following years. The District is planning the second hybrid public meeting for the Corkscrew Watershed Initiative for August.
