|
Federal
Status:
|
Threatened |
|
Date
Listed:
|
43
FR 34479; August 4, 1978. |
|
Description:
|
Longer
fangs than other rattlesnakes. Upturned or "pinched" internasal
and canthal scales which form a ridge around the front
of the snout. Relatively small body sixe. Dorsal coloration:
pale cross-bands with dark edges in a grayish tan background.
Resembles an oak branch. |
|
Population:
|
Entire
|
|
Range:
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U.S.A.
(NM, AZ), Mexico. Sierra de San Luis (Sonora and Chihuahua),
Animas Mountain (New Mexico), and the Peloncillo Mountains
(Arizona and New Mexico). Less than 30 individuals have
been documented in the Peloncillo Mtns. |
|
Habitat:
|
Mountainous
terrain at moderate elevations. Pine-Oak vegetation in
sheltered canyon bottoms in NM & AZ with rocks, leaf litter,
and mesic conditions. In Mexico in the central and southern
parts of its range it is found on elevated plateaus. |
|
Behavior:
|
Exhibits
arboreal behavior occasionally. |
|
Life
Cycle:
|
Active
from July through September. Ovoviviparous (female gives
birth to live young which are hatched inside her oviduct).
C. willardi is biennial (females mate in one summer, give
birth in the next). Gestation is 13 months and young are
born between August 1 and October 15. Newborns share the
same space with the mother and leave within a few days.
Mortality of newborns is caused by predation, lack of
food and freezing. Active from late March through early
October, with increased surface activity through early
October. Gestation is around 5 months. Litter size averages
5-6 young. (Gestation is fetilization to birth.) Female
willardi probably store male sperm until spring (late
March?) when they ovulate. Birth is in August. |
|
Predation:
|
Hawks/owls. |
|
Forage:
|
Adults
prey primarily on small mammals and lizards, and occassionally
consume birds. Juveniles prey primarily on lizards and
giant centipedes. |
|
Threats:
|
Collecting.
Alteration of habitat: type conversion via fire, cattle
grazing, mining, and deforestation through logging. Predation,
starvation, and disease.
Freezing may not be a real big source of martality. Probably
more wothy of mention is desication due to low surface
area/volume ratio combined with late or absentee monsoon
rains. |
