1 of 4
Anna Irene
Mojave National Preserve
Mojave National Preserve
2 of 4
Bureau of Land Management
Mojave National Preserve
Desert tortoise
3 of 4
K. Kristina Drake
Mojave National Preserve
Baby tortoise emerging from its shell.
4 of 4
Chuck Abbe
Mojave National Preserve
Mojave National Preserve
By Phillip Gomez
An unpretentious little building surrounded by a security fence just off Ivanpah Road near the northeast entrance to Mojave National Preserve has an ambitious purpose: to improve the chance of baby desert tortoises surviving to maturity to produce vital offspring.
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.
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: urban sprawl, overgrazing by livestock, poaching, invasive plants, development of highways and dirt roads, and expanding use of off-road recreational vehicles. The degradation and fragmentation of habitat create barriers for the slow moving tortoise in its search for food and water, and also bring danger from motorists and off-roaders. Eggs of the unborn are sometimes trampled. Also, the lives of many are cut short by an upper-respiratory disease, possibly introduced into the desert by sick pet tortoises that were turned loose by their owners.
Tortoise numbers have diminished by as much as 90 percent in some areas of the Mojave, according to Hughson. In August 1989, the California Fish and Game Commission listed the desert tortoise (Gopherus agassizii) as a threatened species under the U.S. Endangered Species Act of 1973. The U.S. Fish and Wildlife Service followed suit with federal protection in 1991. The Preserve was created in 1994 under the California Desert Protection Act, federal legislation that was intended to protect remaining California desert wild lands.
The act called for large-scale management of the Mojave bioregion west of the Colorado River in conjunction with Joshua Tree and Death Valley national parks, as well as the Bureau of Land Management (BLM). Also in 1994, the U.S. Fish and Wildlife Service completed its Desert Tortoise Recovery Plan, another milestone in large-scale ecosystem planning. The plan required the National Park Service and BLM to work together in planning for the recovery of the threatened species. In the summer of 1996, Molycorp Inc. (not the company that currently goes by that name), operated an open-pit mine and chemical-processing facility between Clark Mountain and Interstate 15 near the Preserve. The company incurred federal, state, and county liabilities after a wastewater pipeline ruptured at the site, spilling 350,000 gallons of water contaminated with hazardous heavy metals and low-level radioactive waste. The spill represented up to 100 times acceptable levels, according to Eric C. Nystrom in his administrative history of the early years of the Preserve. The cleanup cost the mining company $3.6 million. It also diverted Preserve staff from their regular duties to install 6.4 km (4 mi) of fencing to keep tortoises away from the ground that was polluted with toxic waste.
By the late 1990s, Chevron Corp. had acquired UNOCAL, Molycorp’s owner since 1977, and with that purchase came the liabilities for Molycorp’s spill. Chevron and its subsidiary, Chevron Environmental Management Co., now had to deal with the legacy of the spill. Ordinarily, under the Endangered Species Act, compensation paid to a federal agency for damages to habitat would be settled with the purchase and donation of selected land parcels. Instead, an idea arose for construction of a seven-acre research facility in the Preserve to help the population recover using predator-proof holding pens for young tortoises.
The facility is used to conduct experiments to support the recovery work, including a study that would help identify habitat preferences. In these experiments, researchers attach tiny radio transmitters to tortoises that are then released and tracked. Previous studies discovered their attraction to the shoulders of Preserve roadways, where runoff after rains provides drinking water and lusher vegetation. Unfortunately, this can lead to deadly impacts with passing automobiles.
The new research will arm researchers with additional information about tortoise behavior that endangers their survival. Researchers hope that the benefits of nurturing and studying this new generation of tortoise will have a significant impact. “The idea is to augment the natural population in the wild,” Hughson says. “The baby tortoises are protected from predators in regulated pens, segregated by age.”
Most have minimal interactions with the researchers to maintain their fear of humans—also necessary for their survival. The project is intended to continue indefinitely, addressing new tortoise management issues as they arise.
“It’s not just for the Preserve and other parks administered by the Park Service, but for tortoises found on BLM lands and in Fish and Wildlife reserves, too,” she said. “It’s for the recovery of the species.”