 |
Gopher tortoise (Gopherus polyphemus)
|
Gopher tortoises - listed as
threatened in Florida - are candidates for federally endangered status.
According to the Florida Fish and Wildlife Commission, the gopher tortoise
(Gopherus polyphemus) is the only land tortoise native to the U.S. east of the
Mississippi, and its population is rapidly declining. Critical research shows
that the gopher tortoise is falling victim to over harvesting, disease, loss of
habitat from human encroachment and humans relocating them away from their
preferred home base. Another threat is humans running over the lumbering
tortoises as they attempt to cross roadways.
Their decline could present a
greater problem because the gopher tortoise is a keystone species in the
ecosystem in which they reside, meaning that their endangerment would likely
have an adverse effect on other plants and animals within their natural
communities. The tortoise grazes on vegetation and thus disperses seeds that
help the plant community thrive. They are also prolific diggers, burrowing as
deep as 10 feet or more and laterally anywhere from 15 to 48 feet. These
extensive burrows allow for a number of other species to drop in on their
obliging hosts for a brief respite from predators or foul weather, while a few
will stay for life. Research shows that over 350 or more commensal species have
been recorded utilizing gopher tortoise burrows at one time or another.
“The burrow is particularly
important as shelter for the endangered eastern indigo snake and two species of
special concern, the Florida mouse, and the gopher frog,” says Jaime Pawelek, a
biologist at the Guana Tolomato Matanzas National Estuarine Research Reserve. Pawelek
conducts research in coastal northeast Florida within the GTM Research Reserve.
She is currently publishing a paper on gopher tortoise ecology in coastal
habitats with Matthew E. Kimball. Kimball serves as both GTM Research Reserve’s
Research Coordinator and University of North Florida Assistant Professor of
Biology.
 |
| Gopher
toroise burrow at the GTM Research Reserve |
A GTM Research Reserve
comprehensive survey of gopher tortoise burrows began in 2005 on the Guana
peninsula, roughly 950 acres of upland mixed habitat. A second survey in 2007
included the Guana peninsula, as well as a 115-acre stretch of undeveloped
coastal beach dunes. Researchers conducted a third survey in 2011 on both Guana
peninsula and beach dunes.
Because gopher tortoises spend most
of their time inside their burrows, they can be hard for the surveyors to find.
Some even camouflage their digs under vegetation. To discover burrows, a team
of researchers and volunteers systematically traverses the ground in search of
an “apron,” a telltale mound made of excavated soil and sand in front of a
burrow entrance. Once located, records are made of the burrow site via GPS.
Other data collected includes tortoise class size (e.g. adult, sub-adult, or
juvenile) and burrow status (active, inactive, or abandoned).
Results from the three surveys show
burrow numbers remaining stable on the Guana peninsula and increasing on the
beach dunes. While Pawelek says these numbers could possibly result from
differences in survey efforts, she adds that they are hopeful that the increase
is due to a growing population.
To monitor activity of burrow
commensals, Pawelek recently set up motion activated cameras in front of both
active and inactive adult burrows. She positioned each camera facing a burrow
so that it records 30-second video clips whenever it detects animal movement.
The system has recorded an Eastern coachwhip, Southern toad, and several mice
and rats utilizing burrows. Mammals observed near entrances or going in and out
of burrows include Virginia opossums, bobcats, armadillos, marsh rabbits and
raccoons. To see video clips, visit the
GTM Research Reserve’s YouTube channel.
Pawelek reports that data collected
from the trail cameras show that all initially selected inactive burrows have
either collapsed or become active again. She notes that, “Monitoring inactive
burrows through the use of trail cameras has shown how quickly burrow status
changes, thus stressing that these are very dynamic systems.”
To help rescue and rehabilitate the
declining gopher tortoise population, researchers are not just looking at the
burrows and who uses them. They gather facts concerning gopher tortoise habits:
what they prefer to eat, where they reproduce and live, how much terrain an
individual stakes out as their own territory and how they manage to keep rivals
at bay. Published and pooled data will help provide a more thorough picture of
the overall needs of the gopher tortoise. Pawelek believes that by monitoring
the Reserve’s tortoises over time, management decisions can be influenced to
better protect and improve their habitat, which not only benefits the
tortoises, but their burrow commensals as well.
The public is generally not aware
that as the law stands it is illegal to damage a gopher tortoise burrow.
Permits are required to move gopher tortoises from their home territory for
clearing land or for development, in which case the law states, “The gopher
tortoise must be protected, or relocated to a safer area.” The only exception
to needing a permit is for wildlife management to improve habitat.
Anyone seeing an injured gopher
tortoise or any other wildlife species in trouble should report it to the
Florida FWC Hotline at (888) 404-3922. For more information on the research,
restoration, education, and conservation programs at the GTM Research Reserve,
to attend public lectures or join guided trail hikes, call (904) 823-4500 or
visit the
website.
 |
Gopher
tortoise at the GTM Research Reserve
|
GTM Research Reserve
Background
Coastal and Aquatic Managed Areas (CAMA) manages the GTM
Research Reserve along with 41 aquatic preserves, the Florida National Marine
Sanctuary, and the Coral Reef Conservation Program. CAMA’s programs and
activities are designed to help Floridians better understand the state’s
resources by research and education activities and by conserving, restoring,
and protecting Florida’s coastal aquatic resources for the benefit of people
and the environment.
The GTM Research Reserve was established as a partnership
between the state of Florida and the National Oceanic and Atmospheric
Administration. The reserve is one of 28 research reserves operating across the
nation and one of three in Florida. For more information on the GTM Research
Reserve, visit the
GTM Research Reserve website or
http://www.dep.state.fl.us./coastal/sites/gtm. For more information on the DEP
CAMA office, visit their
website.
Author: Susan van
Hoek, GTM Research Reserve Environmental Educator
Sources: Jaime
Pawelek, GTM Research Reserve biologist; Florida Fish and Wildlife
Commission;Gopher Tortoise Facts and Information; and Laws on Gopher Tortoises
in the State of Florida.
SIDEBAR: Question: Why does a gopher tortoise cross the
road? Answer: To get to the other side, which is precisely why Good Samaritans
should never assist a tortoise in the road by putting it back where it came
from. According to scientific studies, the animal really wants to go wherever
it is heading. If returned to its starting point, it will turn around and head
right back into the traffic, still determined to get to the other side.
