Stinging Ant Species at Gopher Tortoise Burrows Change over Time with Habitat Change

Two invasive ant species known to attack vertebrates are common in South Florida: Solenopsis invicta and Wasmannia auropunctata. These two species have strikingly different habitat preferences: S. invicta colonies occur primarily in open, sunny areas such as pastures, lawns, and cultivated fields, while W. auropunctata colonies are most common in shady areas with thick layers of leaf litter. Here, we examined how habitat change may affect the relative impact of these two ant species on gopher tortoises (Gopherus polyphemus) in South Florida. In 2002, 2008, 2012, and 2021, we surveyed ants at tortoise burrows in a section of the Abacoa Greenway, a preserve in Jupiter, Florida, established, in part, to protect gopher tortoises. In the four surveys, we found S. invicta on 16%–33% of the tortoise burrows, primarily near the edges of forested area, although the locations of these edges changed as the forested areas expanded and forest gaps filled in. In contrast, the occurrence of W. auropunctata on burrows increased with each survey, from 3% in 2002 to 39% in 2021. The increase in W. auropunctata appears to relate to increased forest density and the accumulation of leaf litter due reduction mowing and fire suppression. Similar changes may be expected in other Florida natural areas where fire is suppressed.