THE DESERT TORTOISE Gopherus agassazii

1. THE DESERTTORTOISEGopherus agassazii By Karen Bernstein

2. Introduction • State reptile of Nevada & California • The largest reptile in Mojave Desert • K-selected species • Endangered species • Conflicting data about if & why endangered

3. Characteristics • Shell is yellow-brownish to dark brown • Shell averages 15-37 cm in length • Avg weight: male=20 kg, female=13 kg

4. Habitat • Found in NV, CA, UT, AZ & Mexico • Bajadas, alluvial fans, flats, & rocky terrain near scrub communities • Soil is determinant factor • Usually found between 1000-3000 feet

5. Eating Habits • Herbivores • Diet largely depends on food availability • In spring, consume winter annuals • In summer, consume annual grasses (galleta grass)

6. Reproduction • Mating period: March-June, Aug-Sept • Clutch size varies from 2-14 eggs • Incubation period highly variable

7. Hatchling success commonly < 60% • Reach sexual maturity between 14-20 years of age • Lifespan estimated 60-100 years

8. Estivation & Hibernation • Dig underground burrows • Summer burrows generally shorter than winter burrows

9. Physiological Ecology & Adaptations • Do not maintain a daily internal homeostasis • Can tolerate large imbalances of water, energy, & salt • Mobile limbs & claws to dig burrows • Dig depressions in soil to catch rain

10. Biogeography • 3 main populations: Sonoran Desert, Western Mojave Desert, & Eastern Mojave Desert

11. Population Trends • Tortoise population has dropped 90% in the last 50 years • US Fish & Wildlife has challenged these estimates • no concrete evidence to support the idea of a major reduction throughout their range

12. Endangered Species • First listed as threatened in 1990 • Need a permit to kill or collect them

13. Environmental Stresses • Urbanization: habitat loss, vandalism, construction of roads • Off-Road Vehicles (ORVs) • Upper Respiratory Tract Disease (URTD) • Raven Predation • Grazing • Habitat Fragmentation

14. Source: http://www.cnn.com/EARTH/9704/23/tortoise/ Researchers voice hope for desert tortoiseFrom Correspondent Jim Hill

15. Solutions • Relocation Potential • Habitat Conservation Planning (HCPs) • Desert Tortoise National Area (DTNA)

16. Desert Tortoise in the Rain His shell glistens with the moisture of a early winter rain. Small drops have drawn him from his earth-dug bed beneath porch steps- all that remains of a house washed away by fire. The backyard fence, which once kept him from the sight ocean or winding canyon, has also been returned to ash. The chirr of a wren can now be heard from camelia branches which survived, somehow, the red flow of flame to hold new blossoms, fluttering purple and red as perfect as Chinese silk. The tortoise, his head like a lump of lava, takes one club foot step after another, bumps his way across heaved red bricks. He opens his mouth to let his almost human tongue loll out to lap up drops of moisture dark as his eyes.

17. The End Thanks to Tom Stein!