The gopher tortoise, Gopherus polyphemus Daudin, is endemic to the southeastern US, where its populations are declining primarily due to habitat destruction. Tortoises are preyed upon by many species, including the red imported fire ant, Solenopsis invicta Buren, a destructive exotic species now common throughout the tortoises' entire range. We surveyed ants using tuna bait at 154 G. polyphemus burrows in a greenway reserve established to protect the tortoises in a residential area of southeast Florida. We found S. invicta present, typically recruiting to the bait in very high numbers, on the aprons of 33% of the tortoise burrows. Solenopsis invicta occurred significantly more often at burrows within 30 m of the greenway's outer edge than at burrows in more interior parts of the greenway (57% versus 16%). Among the interior burrows, S. invicta occurred significantly more often at burrows directly on two narrow strips of disturbed habitat, along an old fence line and an old pipeline, than at burrows not on these two strips (46% versus 12%). The greenway interior appears to offer tortoises and other species some refuge from S. invicta. However, the long thin design typical of greenways, the inclusion of walking paths through the greenways, and the policies of prescribed burning and reduction mowing used to maintain open habitat for the tortoises all may increase the tortoises' exposure to S. invicta. Solenopsis invicta is also a grave threat to other native species in these reserves, including the many animals that obligately live inside gopher tortoise burrows.