Army suspends Fort Irwin tortoise relocation plans after deaths of 90 animals
The U.S. Army has suspended plans to relocate more than 1,000 desert tortoises from Fort Irwin expansion areas this fall and next spring because at least 15 percent of the tortoises moved earlier this year have died.
About 90 of the 556 tortoises moved in the spring are dead, mostly as a result of coyote attacks.
Army and federal wildlife officials said this week that a timeout is needed to determine how many of the tortoises, a threatened species, would have died anyway and how many deaths should be attributed to the relocation effort.
"We didn't foresee this amount of coyote predation," said Roy Averill-Murray, desert tortoise recovery coordinator for the U.S. Fish and Wildlife Service, in a phone interview Thursday.
Fish and Wildlife granted the permit that allows the tortoises to be moved and has the power to stop the relocation or require changes to ensure the species is not jeopardized.
Biologists tracking relocated tortoises began noticing the deaths within a few weeks after the moves started, according to weekly status reports released by the Army under the federal Freedom of Information Act.
Kristin Berry, a biologist with the U.S. Geological Survey, was tracking 159 of the tortoises in mid-April when she noted that five had been killed by predators and one apparently had been attacked by a predator and then run over by a vehicle. A predator tore off the front leg of another, leaving its femur exposed.
The mortality rate "is extraordinarily high for a three-week period," Berry wrote in her April 15 report.
New Training on Hold
The military wants to move tortoises from 118,674 acres the Army acquired for training maneuvers with faster-moving tanks and longer-range weaponry. About 5,000 troops rotate through the National Training Center at Fort Irwin near Barstow every month.
The Army has an $8.5 million budget to move nearly 2,000 tortoises and track their movements and health for five years.
With the relocation on hold indefinitely, the military's training plans for the new territory also are on hold. No maneuvers will take place on the land until the tortoises are removed, said Fort Irwin spokesman John Wagstaffe.
Coyote attacks on tortoises typically are rare. But ongoing drought has reduced the coyote's normal prey -- cottontails, jackrabbits and small rodents -- so the predators are hunting tortoises throughout their California and Nevada habitats, Averill-Murray said.
Federal wildlife officials will analyze whether relocating the tortoises made them more likely to be eaten. The wildlife service will produce an official "biological opinion" before the relocations resume, Roy Averill-Murray said.
The Army training center is expanding into tortoise habitat to the south and west of the existing 1,100-square-mile base.
Of the total of more than 1,900 tortoises to be moved, Fish and Wildlife officials had expected no more that 136 to die.
About 75 percent of the 556 animals relocated a few miles south of their home range in March and April had radio transmitters that allowed biologists to determine what happened to them, Averill-Murray said. Of those, at least 90 have died. The fate of the 100-plus tortoises without transmitters is unknown.
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, a biologist with the Center for Biological Diversity, said Thursday 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.
Averill-Murray said the relocated tortoises appear to be dying at a rate similar to resident tortoises. He agreed, though, that transplanted tortoises try to return to their original homes. A few have found their way back to the future training area, despite a fence meant to keep them out.
Wagstaffe said the relocation didn't cause all the deaths.
"If a tortoise died of natural causes, it should not be counted against the relocation," he said.
But Anderson characterized the 90 deaths as "a huge hit" on the Mojave Desert tortoise population.
The animals' populations have been shrinking because of habitat loss, disease, predation, crushing by vehicles and people taking them for pets.
The federal government considers the species threatened.
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