Tuesday, August 11, 2009

1,100 Threatened California Desert Tortoises Under Threat From Army

Photo: Desert tortoise. Credit: Rachel Wilson.

The desert tortoise (Gopherus agassizii) is a species of tortoise native to the Mojave and Sonoran deserts of the southwestern United States and northern Mexico.

During the 1920s, there were 1,000 California desert tortoises per square mile in the Mojave Desert. Within only 70 years, in 1990, the desert tortoise was listed as a threatened species through the US Fish and Wildlife Endangered Species Act.

The tortoises' decline is due primarily to loss of habitat caused by uncontrolled cattle grazing on the delicate desert grasses that are the base of the tortoise diet. The desert tortoise is an herbivore. Grasses form the bulk of its diet; but, it also eats herbs, annual wildflowers; and, new growth of cacti, as well as their fruit and flowers.

Much of the tortoise’s water intake comes from moisture in the grasses and wildflowers they consume in the spring. Without an adequate moisture intake in the spring, the tortoise may not live to see the next spring. A large urinary bladder can store over forty percent of the tortoise's body weight and enables the tortoise to go a year without water if they have had adequate access to the moisture-bearing grasses that sustain it over the year.

Currently, the tortoises' main survival danger is raven predation on hatchlings and the upper respiratory disease syndrome (URDS) which is believed to have been introduced into the wild population in the early 1980's.

As it prepares to expand training operations at Ft. Irwin in the Mojave Desert, the U.S. Army is again proposing to move more than 1,100 threatened California desert tortoises -- an unprecedented number of an endangered species that has not fared well during previous relocations.

Moving desert tortoises is not always successful. In fact, it can be downright unsuccessful most of the time. The Army relocated more than 600 of the animals last year; but, had to suspend the $8.7-million program after the first phase. Officials noted high mortality rates among the newly-relocated tortoises.

About 90 animals were found dead from suspected coyote predation. However, Clarence Everly, natural and cultural resources program manager at Ft. Irwin, is quick to point out that only one animal died during the actual physical relocation.

Ninety tortoises dead out of 600 relocated is still approximately a loss of one in seven animals. No matter how they died whether in the actual relocation or as a result of the relocation, one in seven animals is inexcusable in any relocation effort – especially one where the animals are already a threatened species.

The sheer numbers of tortoises proposed to be moved in this latest operation, beginning next spring through 2012, alarms conservationists.

"Nothing's ever been done on this scale before," said Ileene Anderson, a biologist with the Center for Biological Diversity, who says a total of 252 tortoises have died in the translocation area. "Every time the animals recognize that they don’t know where they are, they have some built-in mechanism that tells them to head for home and they make a break for home." Read their press release here.

This homing instinct is so strong that in the last move, some tortoises traveled up to five or six miles to get back to their home range, Anderson said.

In their infinite wisdom, the army wants to relocate the already stressed tortoises to a drought-ravaged area of the western Mojave where even more stress will be placed on these animals.

The desert tortoise population is already declining fast; it doesn't need this new problem. "Desert tortoise populations in some areas have declined by as much as 90% since the 1980s and the Mojave population is listed as threatened. It is unlawful to touch, harm, harass or collect wild desert tortoises." Unless you are the Army, it would seem.

Following is a video of a Desert Tortoise in the wild.

Army-produced video update of relocation:

A video from AnimalResQ (the other side of the story):

Want still more information? Desert Tortoise Survival Alliance

No comments: