The threatened desert tortoise (Gopherus agassizzi), which had thrived for more than three million years and is the California State Reptile, is on the ropes, battered by incursions into its ancient habitat and a respiratory disease connected to human contact. Now, a translocation program at Fort Irwin, moving long-established tortoise populations out of newly designated combat training grounds and onto other public lands, has encountered grave morbidity as at least 15% of the tortoises have already died after just a few months. The military has suspended the relocation program for now.
Coyote predation at an unusually high rate has been blamed.
Biologists theorize the problem may be connected to severe drought conditions, which have killed off plants and triggered a crash in rodent populations. As a result, coyotes, which normally thrive on kangaroo rats and rabbits, are turning to tortoises for sustenance.They also point out that translocated tortoises tend to wander, sometimes for miles, making them lumbering targets for hungry predators.
Gashes and tooth marks in the shell of one translocated tortoise discovered in April by federal biologists indicated that it had been ripped out of the front of its carapace.
Other threats include vehicle traffic and an infectious respiratory disease. The disease was prevalent in the relocation area, and now the newcomers are catching it. - Los Angeles Times
Translocation is a highly controversial mitigation practice that has been rejected on previous occasions. Ileene Anderson, a biologist with the Center for Biological Diversity, said in a prepared statement quoted in the Times: "We predicted that the translocation of tortoises from Ft. Irwin's expansion would be disastrous and, unfortunately, we were proven right....This whole debacle needs to be significantly rethought. The loss of so many tortoises is certainly not helping this threatened population."
Two environmental groups, the Center for Biological Diversity and Desert Survivors, sued the Army and the Bureau of Land Management in July, contending that the move exposed healthy tortoises to diseased animals and placed them in a poorer-quality habitat.
Ileene Anderson...said...that the relocated tortoises are more vulnerable to coyotes and other predators because, once they are dropped off, they try to return to their homes. Under normal circumstances, they would seek refuge in their burrows, she said.
"It makes them more visible on the landscape, and it makes it easier for coyotes and other predators to spot them and kill them," Anderson said. - Press-Enterprise
Read more in the Press-Enterprise and the Los Angeles Times.
PE.com columnist Cassie McDuff reviews these issues and questions the potential of more "unintended consequences" in a military expansion closer to home:
Now the tortoises face another threat. The Marine Corps wants to expand the Twentynine Palms Air Ground Combat Center onto an off-road recreation area. If displaced off-roaders push the government to open desert land now closed to off-roading, more tortoise habitat could be lost.
If that happens, creatures that coexist with them including burrowing owls could be lost, too. That must not happen.
Efforts to educate a new generation about the tortoise and its desert world continue, however, in the selection of a new "Mojave Max." Per the Las Vegas Sun:
A 10-pound successor to the Mojave Max legacy at the Red Rock Canyon National Conservation Area has been selected to carry on educating people about their role and responsibility in the health of the Mojave Desert.
[snip]
On June 30, the first Mojave Max died of natural causes at an estimated age of 65 years old at the Red Rock Canyon National Conservation Area.
The Mojave Max Emergence Contest encourages students to study the conditions of the Mojave Desert and the behaviors of desert species and then predict when the live Mojave Max will emerge from his burrow each spring. The original Mojave Max emerged as early as Feb. 14 and as late as April 14 during his nine-year tenure.
FOR MORE INFO ON THIS TOPIC: See the Desert Tortoise and Education pages on the MBCA Website. Previous blog posts: Wildlife, Marine Base.
