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THE GOPHER TORTOISE:

THE GOPHER TORTOISE:. A presentation by the Gopher Tortoise Council modified by Nora Demers for the Nature Place, City of Bonita Springs on May 11, 2009. A SPECIES IN DECLINE. “working to conserve the gopher tortoise and the fascinating world in which it lives”.

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THE GOPHER TORTOISE:

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  1. THE GOPHER TORTOISE: A presentation by the Gopher Tortoise Council modified by Nora Demers for the Nature Place, City of Bonita Springs on May 11, 2009 A SPECIES IN DECLINE “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

  2. 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

  3. The Gopher Tortoise(Gopherus polyphemus)

  4. 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)

  5. 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?)

  6. Geographic Range of theGopher Tortoise

  7. 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.

  8. Longleaf Pine Sandhill

  9. Scrub

  10. Pine Flatwoods

  11. Coastal Dunes

  12. Disturbed Sites

  13. The Ecological Role of Fire Promotes diversity Cycles nutrients Alleviates risk of wildfire Regeneration after fire (tender vittles)

  14. 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.

  15. The Gopher Tortoise Burrow

  16. 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)

  17. Adaptations for Burrowing Hind foot Forefoot

  18. Burrow Associates

  19. Gopher Frog (Rana capito) Spend most of their time in burrows, -species of special concern in FL

  20. Eastern Diamondback Rattlesnake(Crotalus adamanteus) CAREFUL- there can be venomous snakes in those burrows!

  21. Eastern Indigo Snake (Drymarchon corais couperi) Largest (indigenous) snake in N.A. -glassy black with red head and chin Federally protected threatened species

  22. Florida Mouse(Podomys floridana) Occurs only in peninsular Fl. -Excavates side tunnels Species of special concern in Fl.

  23. Life History of theGopher 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

  24. Growth in Gopher Tortoises Each annuli represents about 1 year Rates vary by location and environmental conditions

  25. Sexual Dimorphismin Gopher Tortoises Male- concave lower plastron thick gular projection Female- slightly larger

  26. Courtship Typically breed April to June Lots of head bobbing and nose rubbing

  27. Nesting Lay eggs May to June in apron or sunny sand nearby Single clutch per year (or not at all) Average 6 eggs, up to 25! Size of ping pong balls Incubation time 80-110 days (S to Northern range)

  28. 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

  29. Nest Predation A female may produce a successful nest no more than every 10 years

  30. Nest Predation Also foxes, skunks, fire ants

  31. 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

  32. Hatchling predators Domestic dogs, Fire ants, ‘coons, snakes, hawks

  33. Food Plants Stingingnettle Prickly pear cactus Wiregrass

  34. 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 home- structure of burrow unique (left or right turn)

  35. 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)

  36. Upper RespiratoryTract 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

  37. The Danger: Asymptomatic Tortoises Or is it a danger? Regulations for testing under review

  38. Habitat Loss Development Forestry Practices Mining Agriculture

  39. Habitat loss • Housing & other developments • Citrus groves give way to development in Estero (NDN 3/6/06) Photo by M Forter Daily News

  40. Invasive Species

  41. Gopher Tortoises and Roads • Direct effects: • habitat loss • mortality • Indirect effects: • habitat fragmentation • artificial habitat

  42. Roads and Parking lots • Balance desire of humans to enjoy surroundings with needs of native species

  43. Habitat Degradation

  44. 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

  45. Gopher Tortoise Relocation • THE GOOD • Saves individuals • Restocking • Increased knowledge of tortoise movements

  46. 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

  47. The Future

  48. 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)

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