SANIBEL-CAPTIVA CONSERVATION FOUNDATION

The Sanibel-Captiva Conservation Foundation reported that it has been conducting annual gopher tortoise burrow surveys on Sanibel preserves since 2000. Frannie’s Preserve and C. R. Johnston Tract surveys began in 2000, while the Dayton Preserve, Walker Preserve and Wulfert Gopher Tortoise Preserve began in 2007.

The average active burrow percentages across all five preserves stayed relatively consistent between 2007-21, with a decrease of 2.3% of active burrows overall. However, Hurricane Ian in September of 2022 changed that consistency.

“Hurricane Ian’s storm surge event drastically altered the landscape with dead overstory trees and shrubby vegetation, flooding that left Gulf soils as the water receded, and many collapsed or filled gopher tortoise burrows,” wildlife biologist Mike Mills said.

Post-Ian, the SCCF documented a 59.2% loss of all active burrows on all sites, with no burrows remaining at all at the Dayton Preserve. Although this year’s survey still found a drop of 5.8% in active burrows, the future is promising for Sanibel’s gopher tortoise population.

“An inactive or abandoned burrow does not necessarily mean the loss of the tortoise, just that the burrow is not being used,” he said.

SANIBEL-CAPTIVA CONSERVATION FOUNDATION A gopher tortoise by its burrow.

Fourteen burrows that were considered inactive or abandoned in 2022 are now actively being used again, while eight new ones were discovered.

A state-threatened and keystone species, gopher tortoises require an open-canopy habitat and an abundance of grasses and ground-level plants. Historically, Sanibel was made up of this type of habitat, but due to the lack of naturally occurring fires and the changing of the island’s hydrology, closed-canopy hardwood hammocks started to dominate the landscape.

“Since Hurricane Ian, SCCF continues to remove a large amount of dead vegetation, opening up areas of the island that haven’t been exposed to sunlight for decades,” Mills said. “This will allow the naturally occurring grassland habitats to return and offer more areas for gopher tortoises to thrive.”

The habitat management team is also thinning out shrubby and woody vegetation in uplands to attract gopher tortoises back to the areas.