COMMISSION

cross through Ocotillo Wells SVRA, originating in Anza-Borrego Desert State Park in the
north and west. These washes fill and flow with water during large rain events that typically
occur in the summer months or intense winter storms and are occasionally subject to flash
flooding. Ocotillo Wells SVRA is in the rain shadow of the Santa Rosa Mountains of the
Peninsular Range. The average annual rainfall is 3.45 inches. Temperatures range from 70
to 115 degrees Fahrenheit in the summer and from near freezing to 80 degrees Fahrenheit
during the day in the winter.
Due to variability found in elevation, terrain, soils, and many other factors, a wide variety
of Colorado Desert vegetative communities is present in the park. These include creosote
bush scrub and creosote white burr sage scrub, mesquite, Palo Verde woodlands,
brittlebush scrub, and woody aster badland wash benches.
Flat-Tail Horned Lizard Monitoring Program
Since 1994, Ocotillo Wells SVRA has been a partner in the ICC whose responsibility is
to determine state and federal policy on the flat-tailed horned lizard (FTHL) (Phrynosoma
mcallii) management, research protocols, and protection status. As part of the cooperative
agreement among members of the ICC, Ocotillo Wells SVRA conducts annual FTHL
population surveys and research to bolster understanding of its unique ecology.
Ocotillo Wells SVRA utilizes occupancy and demography studies to collect data. Occupancy
surveys help park staff gain a broad perspective on population trends so that Ocotillo Wells
SVRA may identify extinction or extirpation events as they happen. Demography surveys
paint a detailed portrait providing information on immigration, emigration, recruitment, birth
rate, and mortality. The Ocotillo Wells SVRA resource team conducts occupancy surveys
on 80 plots from June through August each year. Demography surveys occur over the
course of two weeks in September at a few select plots. In 2016, the resource team had
nine people dedicated to conducting these surveys.
Ocotillo Wells SVRA submits annual survey data to
the ICC, whose statisticians analyze the information
for modeling and projection of lizard populations
throughout its range.
CDWF currently list the flat-tailed horned lizard as a
Species of Special Concern; however, the California
Fish and Game Commission is in the process of
making a ruling on changing the species conservation
status. The OHIMVR Division developed an interim
Flat-tailed horned lizard
management plan that will be followed during the period the lizard is under consideration
for state listing as endangered. The OHMVR Division is also developing an Incidental Take
2017 Program Report 107