Download - Wildlife Ecology and Conservation

Gopher Tortoise
Gopherus polyphemus
Photo courtesy of Joan Berish
•Identification
•Natural History
•Habitat
•Status
•Threats to Species
•Importance of Species
•Management and Conservation
Photo courtesy of Camp Blanding
Identification
• Domed shell and stumpy
feet
• Shovel like front feet
adapted for digging
Photo courtesy of Joan Berish
• Long-lived
• Average adult size is 9-11 inches
• Related species in U.S.: Texas tortoise and desert tortoise,
both in genus Gopherus
Identification
• Gopher tortoise has unhinged plastron and
carapace is generally unmarked
• Gopher tortoise lives in dry upland habitats
Photo courtesy of Joan Berish
Gopher Tortoise
Florida Box Turtle
Photo from Jamie Barichivich
Hatchling Identification
Photo courtesy of Lora Smith
Yellowish orange in color
Approximately 1.7 inches in length
Age Determination in Tortoises
Photo courtesy of Lora Smith
Close up of adult scute
Hatchling tortoise without growth rings
Sexual Dimorphism
Males:
– slightly smaller than females
– have projection on plastron (underside of shell)
– plastron is concave (indented)
Photo courtesy of Joan Berish
Natural History
•Distribution
•Diet
•Activity
•Reproduction
•Hatchling Growth & Survival
•Burrows
Distribution
photo from Joan Berish
Diet
• Grasses and other grass-like plants
• Legumes (plants with beans or pods)
• Fruits, including blackberries and fruit of the prickly
pear cactus
• Legumes seem to be a favorite of juveniles
photo from Joan Berish
Activity
Photo courtesy of Camp Blanding
• Active during warmest part of day, except in summer
• Spends most of its time in burrow, however most of its
time above ground is spent basking, followed by walking
and feeding
• Activity reduced during winter, especially in northern
parts of range
Reproduction
• Female tortoises take 10-21 years to reach reproductive
maturity, males take about 9-16 years.
• Mating occurs in early spring and nesting occurs in
summer.
• Females lay clutch of about 6 eggs.
photo from Joan Berish
Reproduction
Photo courtesy of Lora Smith
Photo courtesy of Lora Smith
• Nests are sometimes dug in apron of burrow. The
nest site must be in a sunny area.
• Predation on eggs is high, especially during first
week of deposition.
• Predators on nest are raccoons, opossums, and
armadillos.
Photo courtesy of Lora Smith
Hatchling Growth & Survival
Photo courtesy of Joan Berish
• Incubation time depends on climate; eggs take longer to
hatch in northern part of range
• Eggs hatch in about 80-90 days
Photo courtesy of Lora Smith
Young may construct small burrows, or bury themselves in
leaf litter or sand
Hatchling Growth & Survival
The lowest survival rate of a gopher tortoise’s life
occurs during the first few months
Photo courtesy of Lora Smith
Growth & Survival
• Only predators on
adult tortoises are
humans and dogs
• Defensive position
• Expulsion of waste
Photo courtesy of Joan Berish
Burrows
• Average 15 feet long and 6.5 feet deep
• Provide refuge from weather, predators, environmental
disturbances
• Apron makes burrow easily recognizable
Photo courtesy of Joan Berish
Burrows
• Remain at relatively
constant temperature and
humidity year-round
• Burrows are at center of
home range activity
• One tortoise may use more
than one burrow during the
active season
Photo courtesy of Lora Smith
Habitat
Photo courtesy of Joan Berish
Habitat
Photo courtesy of Lora Smith
Necessary Components
• Well drained loose soils
• Sufficient low-lying
herbaceous vegetation
• Sunlit sites
Sandhill Habitat
Habitat
• Primarily inhabit sandhills
• Sand pine scrub, live oak hammocks, dry prairies, and
mixed hardwood pine communities
photo courtesy of Joan Berish
Coastal Strand
• Disturbed areas, such as roadsides and old fields
• Also found in coastal dunes
Status
• Species of Special
Concern in FL
• Protected to some extent
across all its range
• Unlawful to take, harm,
harass or possess tortoises
photo from Joan Berish
Threats
• Direct threats from humans
• Habitat destruction
• Fire suppression
• Road mortality
• Disease
Photo courtesy of Mark Hostetler
Direct Threats
• Molestation from
humans
• Predation from dogs is
common, but its effects
on tortoise populations
unknown
photo courtesy of Lora Smith
Direct Threats
• Major food source during the Depression
• Collection for tortoise races
Photo courtesy of Lora Smith
Habitat destruction
Loss and/or destruction of upland habitat caused by:
Photo courtesy of Camp Blanding
• urbanization
• mining activities
• pine plantations
Tortoise Habitat
Habitat Destruction
Why aren’t sand pine plantations suitable tortoise habitat?
• Pine plantations are monocultures dominated by pine
trees with low plant diversity
• Monocultures prevent:
–Growth of low-lying food plants, such as legumes and cacti
–Adequate sunlight for nesting sites
• Some clear-cutting and site prep practices may harm
tortoises
Fires
• Fires are a natural part of sandhill community
• They keep the habitat suitable for tortoises by:
–stimulating higher yields of tortoise food plants
–preventing community succession
Photo courtesy of Joan Berish
Photo courtesy of Camp Blanding
Photo courtesy of Camp Blanding
Road Mortality
Photo courtesy of Lora Smith
Tortoise road mortality is even high in rural areas.
Disease
Upper respiratory tract disease, (URTD),
caused by a naturally occurring bacterium
known as a mycoplasma
infected
healthy
Photo courtesy of Joan Berish
Photo courtesy of Joan Berish
Disease
• Disease probably made worse by stress put on tortoise
populations by humans
• Disease may be spread into uninfected population by
tortoise pet releases and tortoise relocation
• Spread by close contact
• Seemingly healthy tortoise may be a carrier
• Tortoise may get “sicker quicker” upon secondary
infection
Disease
Complications of URTD:
• Blood tests only report
exposure, not infection of disease
• Mycoplasmal infection known
to cause die-offs in western
Gopherus species
• Effects on gopher tortoise not
fully understood
photo courtesy of Joan Berish
• URTD may be spread through
tortoise relocation projects
Disease
Currently populations of infected tortoises
are being monitored to learn about URTD’s
effects on the species
Photo courtesy of Joan Berish
Importance of Species
Burrows are important refuges for many
organisms in the tortoise’s community
Gopher Frog
Photo courtesy of Camp Blanding
Importance of Species
Burrow Occupants
Gopher Frog
Photo from Camp Blanding
Hognose Snake
Indigo Snake Photo from Camp Blanding
Photo by Jamie Barichivich
Importance of Species
Photo courtesy of Camp Blanding
• Keystone species: Removal of the species from
its community would have a harmful effect on many
other organisms in the community
• Protection of tortoises and their burrows helps all
organisms that use the tortoise burrows
Importance of Species
Gopher tortoises inhabit two declining ecosystems:
• scrub habitat, home to the threatened scrub jay
• old longleaf pine communities, home to the endangered
red-cockaded woodpecker
Photo courtesy of Camp Blanding
Importance of Species
• Tortoises are seed dispersers
• Burrowing returns leached
nutrients to the surface
• Burrow mounds provide a
foothold to young plants
• Aprons provide suitable sand for
“swimming” skinks
Photo courtesy of Lora Smith
Sand Skink
photo by Jamie Barichivich
Mitigation
• Tortoise mitigation
and conservation is a
controversial issue
between biologists and
land developers
photo courtesy of Camp Blanding
• Developers have
several options when
building on land with
active burrows
Mitigation
Developer’s Options
• Do not develop on site with
active burrows
• Avoid burrows
• Tortoise captured, released
on-site
• Mitigation banking
• Tortoise relocation off-site
photo courtesy of Joan Berish
Mitigation banking
• Highly controversial
• Allows developer to
entomb tortoises
• Suitable habitat
purchased elsewhere
Photo courtesy of Lora Smith
Relocation
• An environmental consultant is hired to capture and
relocate tortoises
• Potentially harmful to existing population
• Low site fidelity
photo courtesy of Camp Blanding
Conservation Strategies
• Habitat management
• Establishment of
preserves
• Protection from
poaching
• Public education
photo courtesy of Alan Long
Conservation Strategies
photo courtesy of Camp Blanding
• Restock populations in areas tortoises once lived
• Nest enclosures to increase hatching rate and and provide
head start for hatchlings
Summary
• Gopher tortoises are protected throughout their range,
listed as Species of Special Concern in Florida
• Must have well drained soil, low-lying herbacious
plants, and enough sunlight for nests
• Habitat loss is the major threat on tortoises today
• URTD threat increased due to stress on populations
Summary
• Burrows provide refuge for over 350 animals
• Protection of tortoise habitat provides protection
for other listed species
• Relocation option is least effective because it does
not provide permanent solution
• Controlled fires, habitat preservation, and plans to
increase survivorship of eggs and young are all
conservation strategies
What you can do to help:
• Notify Florida Fish and Wildlife Conservation Commission
(FWC) if land with active burrows is slated for development.
http://wld.fwc.state.fl.us/fwc_dir/offices.htm
• Report harassing, collecting, or killing of tortoises to
FWC.
• Do not attempt to relocate tortoises yourself.
• Join the Gopher Tortoise Council. Visit their website at
• www.gophertortoisecouncil.org
Photo courtesy of Camp Blanding
For More Information
To find out more about gopher tortoises
in Florida, visit the UF/IFAS extension
website at:
www.ifas.ufl.edu/extension
www.floridaconservation.org
Acknowledgments
• Created by Audrey Owens and Dr.Mark
Hostetler, Department of Wildlife Ecology
and Conservation, IFAS, University of
Florida
• In conjunction with: Joan Diemer-Berish,
Florida Fish and Wildlife Conservation;
Lora Smith, Gopher Tortoise Council
• Photo credits: Camp Blanding