Tortoises in the Mojave Desert (CA)
A Head Start for an Endangered Species
The cryptic lives of tortoises—spent predominantly in underground burrows— and the many years that it takes for them to reach sexual maturity and to reproduce, have made it difficult for conservation biologists to conduct field studies.
So, the National Park Service, together with the U.S. Fish and Wildlife Service, Chevron Corp., Molycorp Inc., and two universities have partnered to create a working facility to try to gain a better understanding of tortoise behavior that affects their survival. The Ivanpah Desert Research Facility is staffed by a small team of faculty and Ph.D. candidates from the Savannah River Ecology Laboratory of the University of Georgia and from the University of California, Davis. For this long-term research project, juvenile tortoises are being “recruited” over a 20-year period and nurtured in this facility until they are capable of joining the Ivanpah Valley’s population with a reasonable chance for survival. The idea for this experiment in wildlife management, entitled Desert Tortoise Juvenile Survivorship at Mojave National Preserve—or Head Start to researchers—is similar to the principle underlying children’s nursery schooling: giving kids a head start in life.
In the case of the tortoise, the goal is to gain time for the reptile’s shell to develop and harden to make the young reptiles safe from predators. Adult tortoises with hardened shells have few predators, but juveniles are extremely vulnerable for the first four or five years of life.
“It’s all about the predation,” says Debra Hughson, the Preserve’s chief of science and resource stewardship. “The purpose of Head Start is to allow them to survive.” How many tortoises are there in the Preserve? “Nobody knows exactly, but only a small percentage make it to adulthood,” Hughson said.
This, coupled with the late maturity of the tortoise, which can take 18 to 20 years to reach breeding age, makes for long odds in the game of survival in the desert.
Once numerous in the Mojave, the desert tortoise began experiencing loss of natural habitat from a variety of sources by the late 1980s:
Tortoise of the Mojave