BIOLOGICAL DATA AND HABITAT REQUIREMENTS
WILDLIFE SPECIES: Gopherus agassizii | Desert Tortoise 



TIMING OF MAJOR LIFE HISTORY EVENTS : 
Mating -  Begins in May and continues at various intervals until autumn
Breeding age -  15 to 20 years
Nesting -  Typically May through July; may nest in autumn
Incubation -  118 days
Clutch size -  4 to 13 eggs; may lay more than one clutch per season
Life span -  50 to 100 years
Hibernation -  October through April; may estivate in shallow burrows 
              during the hot, dry summer months [2,7,13,17,19,22].


PREFERRED HABITAT : 
Desert tortoises live in hot, dry desert shrub areas.  They seek shade
under rocks or shrubs during intense heat [7].  In California, tortoises
frequent areas with high annual bloom potential and a diverse array of
perennials and cactus scrub.  They are found at elevations between 1,000
and 3,000 feet (300-920 m) [13].  In the Mojave and Sonoran deserts
tortoise frequent steep, rocky slopes [6].


COVER REQUIREMENTS : 
Desert tortoises dig burrows for winter hibernation and shallow holes
for summer estivation.  The soil must be a fine gravelly and/or sandy
loam, with some clay for burrow stability [13,22].  Burrows are dug in
the open or under shrubs and rocks.  They can also be found in the banks
of gullies and washes [2].  In addition to burrows, tortoises sometimes
rely on shrubs for cover during the day.  In Arizona tortoises use rock
outcrops for burrows [16].


FOOD HABITS : 
Desert tortoises are primarily herbivorous; they eat forbs, grasses, and
a few shrubs.  The bulk of their diet consists of annual wildflowers,
annual and perennial grasses, perennial shrubs, and cacti.  Some genera
include Astragalus, Camissonia, Coreopsis, Cryptantha, Erodium,
Euphorbia, Gilia, Lupinus, Malacothrix, Mentzelia, Phacelia, Plantago,
Bouteloua, Bromus, Festuca, Schismus, Sphaeralcea, and Opuntia
[2,10,22].


PREDATORS : 
Desert tortoise populations suffer from a wide variety of predators,
most notably man.  Grazing livestock can trample young and adult
tortoises both in and out of their burrows [2,19,21].  New hatchlings
are frequently taken by common ravens (Corvus corex) [1,6].  Other
animal predators include the desert bobcat (Lynx rufus baileyi), desert
coyote (Canis latrans estor), desert kit fox (Vulpes macrotis arsipus),
gray fox (Urocyon cinereoargenteus), badger (Taxidea taxus), western
spotted skunk (Spilogale gracilis), Nevada ringtail (Bassariscus astutus
nevadensis), and the golden eagle (Aquila chrysaetos) [22].


MANAGEMENT CONSIDERATIONS : 
Desert tortoises can suffer from a highly contagious upper respiratory
disease which is capable of destroying entire populations.  The disease
is thought to be contracted from tortoises kept as pets whose owners
have released to the wild [19].


REFERENCES : 
NO-ENTRY

Related categories for Wildlife Species: Gopherus agassizii | Desert Tortoise