Endangered Species Recovery Program

Utility of 10-day censuses to estimate population size
of blunt-nosed leopard lizards

Published in:
California Fish and Game, 83:144-152

by

David J. Germano
Dept. of Biology
California State Univ., Bakersfield
Bakersfield, CA 93311

Daniel F. Williams
San Joaquin Valley Endangered Species Recovery Program

and

Larry R. Saslaw
Bureau of Land Management
3801 Pegasus Drive
Bakersfield, CA 93308

Abstract

The blunt-nosed leopard lizard, Gambelia sila, is an endangered species that increasingly is losing habitat within its range in the San Joaquin Valley of California. Determining local population size of this species sometimes is necessary for its conservation. Measuring population size from short-duration censuses can save time and money compared to total counts or mark-recapture methods, but the census must be shown to be accurate. From 1990 to 1994, we completed full-season censuses of blunt-nosed leopard lizards that were marked and recaptured on two plots on the Elkhorn Plain, California. We compared estimates of population size for full-season censuses (considered a true estimate of abundance) to 10-day counts of adult/yearling cohort (active April-July) and hatchling cohort (active July-October). We found that 10-day censuses can be used to accurately index population size of blunt-nosed leopard lizards, at least in foothill habitat.