RED IMPORTED FIRE ANTS (HYMENOPTERA: FORMICIDAE) AT GOPHER TORTOISE (TESTUDINES: TESTUDINIDAE) BURROWS

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.