THE GOPHER TORTOISE: A SPECIES IN DECLINE A presentation by the Gopher Tortoise Council modified by Nora Demers for the Nature Place, City of Bonita Springs on May 11, 2009 “working to conserve the gopher tortoise and the fascinating world in which it lives” This program was partially funded with grants from the Georgia Department of Natural Resources and the League of Environmental Educators in Florida Acknowledgments The following people generously donated photographs or slides for this presentation: Joan D. Berish, C. Kenneth Dodd, Jr., George L. Heinrich, Sharon Hermann, Joseph W. Jones Ecological Research Center, Lee County Parks & Recreation, Barry Mansell, Henry Mushinsky, Lora L. Smith, Jill Kusba, and Nora Demers Developed by Laura Wewerka and Lora L. Smith The Gopher Tortoise (Gopherus polyphemus) Gopherus polyphemus Chordata- spinal cord and bony vertebrae Reptilia- scales, amniotic eggs, ectothermic Testudines- flattened fused bones, ribs and vertebrae Testidinoidea- clawed elephantine hind feet, no webbing Gopherus- burrower Polyphemus- lives in cave (Greek) Evolution Tortoiselike fossils found from early Triassic (250 mya) originating in North America over 60 million years ago Gophers first seen during Pleistocene (500,000 to 2 mya) Only land turtle remaining in SE US (also only burrowing tortoise – is there a relationship?) Geographic Range of the Gopher Tortoise Legal Status Alabama- state listed as Protected; federally listed as Threatened west of the Tombigbee and Mobile Rivers. Florida- state listed as Threatened (“harm” enters protection terminology) Georgia- state listed as Threatened. Louisiana- state and federally listed as Threatened. Mississippi- state listed as Endangered; federally listed as Threatened. South Carolina- state listed as Endangered. Longleaf Pine Sandhill Scrub Pine Flatwoods Coastal Dunes Disturbed Sites The Ecological Role of Fire Promotes diversity Cycles nutrients Alleviates risk of wildfire Regeneration after fire (tender vittles) Keystone And Indicator Species Gopher tortoises are keystone species. They alter the habitat by constructing and maintaining their burrows, which have over 350 commensals and associates. Tortoises are also considered “indicator” species, used as an indicator of ecosystem health. The Gopher Tortoise Burrow Burrow details Protect from temperature extremes and predators One opening Max. length 13 m (40 feet), depth 3m (10’) Burrow has ledge at end where tortoise rests, nice humidity In SW Florida burrows are usually shorter and shallower (water table primary influence) Adaptations for Burrowing Hind foot Forefoot Burrow Associates Gopher Frog (Rana capito) Spend most of their time in burrows, -species of special concern in FL Eastern Diamondback Rattlesnake (Crotalus adamanteus) CAREFULthere can be venomous snakes in those burrows! Eastern Indigo Snake (Drymarchon corais couperi) Largest (indigenous) snake in N.A. -glassy black with red head and chin Federally protected threatened species Florida Mouse (Podomys floridana) Occurs only in peninsular Fl. -Excavates side tunnels Species of special concern in Fl. Life History of the Gopher Tortoise Average length: 10-12 inches (25-30 cm) Average weight 4 kg (9 lbs) Females slightly larger than males- sexually mature when 15-20 years old Slow growing (depending on environment) Can live more than 60 years Growth in Gopher Tortoises Each annuli represents about 1 year Rates vary by location and environmental conditions Sexual Dimorphism in Gopher Tortoises Maleconcave lower plastron thick gular projection Female- slightly larger Courtship Typically breed April to June Lots of head bobbing and nose rubbing Nesting Average 6 eggs, up to 25! Size of ping pong balls Incubation time 80-110 days (S to Northern range) Lay eggs May to June in apron or sunny sand nearby Single clutch per year (or not at all) Sex Determination The incubation temperature of the nest determines sex If over 30 degrees Celsius, female (80 degrees F); if under 30 degrees, male. Difficult to determine sex of juveniles and sub-adults Males apparently mature sooner than females Nest Predation A female may produce a successful nest no more than every 10 years Nest Predation Also foxes, skunks, fire ants Hatchling Gopher Tortoises Hatchlings are 1-2 inches long (25-30 cm) Use adult burrows or excavate their own Soft shell renders them vulnerable to predators for first 7 years Hatchling predators Domestic dogs, Fire ants, ‘coons, snakes, hawks Food Plants Stinging nettle Prickly pear cactus Wiregrass Home Range Size Range depends on habitat usually stay near a burrow Adult Females: 0.2 – 1.4 ac (0.1 – 0.6 ha) (house lot size) Adult Males: 1.1 – 3.2 ac (0.4 – 1.3 ha) Juveniles (<4 yrs): 0.02 – 0.9 ac (0.01 – 0.4 ha) Most have more than one burrow to call homestructure of burrow unique (left or right turn) Why Gopher Tortoise Populations are in Decline: Problems and a Few Solutions Races Mechanical tortoises in San Antonio Fl. Food “Hoover Chickens” (GTC helped end legal harvest in 1988) Upper Respiratory Tract Disease (URTD) Caused by mycoplasm (obligate intracellular pathogen like t.b.) Transmission by nose rubbing etc Symptoms • Clear or white nasal discharge • Watery eyes • Swollen eyelids The Danger: Asymptomatic Tortoises Or is it a danger? Regulations for testing under review Habitat Loss Development Forestry Practices Mining Agriculture Habitat loss Housing & other developments Citrus groves give way to development in Estero (NDN 3/6/06) Photo by M Forter Daily News Invasive Species Gopher Tortoises and Roads Direct effects: • habitat loss • mortality Indirect effects: • habitat fragmentation • artificial habitat Roads and Parking lots Balance desire of humans to enjoy surroundings with needs of native species Habitat Degradation Mitigation Options in Florida Avoid impacting burrows Set aside on-site preserves/on-site relocation Relocate tortoises off-site Incidental Take/ Mitigation Banking • Protect (and manage) habitat off-site Gopher Tortoise Relocation THE GOOD • Saves individuals • Restocking • Increased knowledge of tortoise movements Gopher Tortoise Relocation THE • • • • • • BAD… AND THE UGLY Net loss of habitat Tortoises often leave relocation site Disruption of resident populations Labor intensive/costly Transmission of disease Diverts conservation funds The Future Current Research Upper Respiratory Tract Disease- distribution and impacts- now believed to have co-evolved with tortoises Investigations into impacts of fire ants on gopher tortoise populations in Federally threatened part of range Studies of other upland species: southern hognose snake; eastern indigo snake; red-cockaded woodpecker Summer of ’04 first low frequency sound communications (Eliz. von Miggenthaler- Prez. of Fauna Communication Society) Land Management: the Use of Prescribed Fire Creative Conservation at Work The Nature Conservancy- habitat acquisition and land stewardship Mitigation Banking County-wide Gopher land conservation measures Tortoise Conservation Initiative Tortoise Reserve Program Local Mitigation options Lee County – Hickey’s Creek Mitigation Park--NOT a relocation center – Persimmon Ridge, Caloosahatchee Regional Park, 10-mile Canal Park relocation for private (developers) mitigation – Gator Hole -20/20 lands (off Corkscrew Rd.) for public improvement (3-oaks expansion) Collier County- Maureen Bonness good contact What You Can Do Landscape with native plant species (many are food plants of gopher tortoises) Become active in conservation organizations that promote habitat protection and management Be a watch dog for tortoises Write to your local politicians about issues that affect tortoises and their habitat Vote! Listing in Florida FWC Draft Biological Status Report (Nov. ’05) Criteria for State Listing (Rule 68A-1.00 F.A.C.) Population size reduction due to habitat loss –note that human population has increased 2,161% since 1910 (2003 figure) and has been doubling every 20 years during the 1990’s - pre-European settlement estimate of habitat: 10 million acres, today: 1.7 million acre Meets criteria for classification as Threatened FWC requesting input What to do if You Find a Stray Tortoise “Hands off” unless: On roads, move tortoise to nearest habitat (preferably in direction it was heading) - BEWARE OF TRAFFIC! If injured, contact your local Game Commission or Department of Natural Resources The Mission of the Gopher Tortoise Council Education Habitat protection Research For More Information: Write to us at the following address: Gopher Tortoise Council c/o Florida Museum of Natural History P.O. Box 117800 University of Florida Gainesville, FL 32611-7800 Visit our web site: www.gophertortoisecouncil.org Now a short quiz images courtesy of Jill Kusba Can you find the tortoise? How big is this tortoise? HINT: It is a one-year old hatchling Can you find the burrow? The Future