THE DESERT TORTOISE Gopherus agassazii

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THE DESERTTORTOISEGopherus agassazii
By Karen Bernstein
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Introduction

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

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Characteristics

• Shell is yellow-brownish to dark brown
• Shell averages 15-37 cm in length
• Avg weight male20 kg, female13 kg

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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

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Eating Habits

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

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Reproduction

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

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• Hatchling success commonly lt 60
• Reach sexual maturity between 14-20 years of age
• Lifespan estimated 60-100 years

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Estivation Hibernation

• Dig underground burrows
• Summer burrows generally shorter than winter
  burrows

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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

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Biogeography

• 3 main populations Sonoran Desert, Western
  Mojave Desert, Eastern Mojave Desert

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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

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Endangered Species

• First listed as threatened in 1990
• Need a permit to kill or collect them

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Environmental Stresses

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

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Source http//www.cnn.com/EARTH/9704/23/tortoise/
Researchers voice hope for desert tortoise
From Correspondent Jim Hill
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Solutions

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

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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.
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The End
Thanks to Tom Stein!