All of the tortoises are being tracked with a VHF radio transmitter roughly the size of a $3 stack of quarters, and 24 of them are also sporting GPS tracking units double the height of a deck of cards but not as wide or long.
The San Diego Zoo placed the tortoises in the wild after they were nurtured at the Desert Tortoise Conservation Center, a partnership between the zoo and federal and state agencies. The portable technology carried by the tortoises will make it easier for the zoo’s workers to learn about the creatures’ movement patterns and habitat conditions.
Last year, the center released 100 tortoises into the desert. In 2009, the San Diego Zoo began partnering with the U.S. Fish and Wildlife Service, which oversaw the Desert Tortoise Conservation Center.
“Our mission is to aid in the recovery of the desert tortoise,” said Paula Kahn, conservation program manager with the San Diego Zoo Institute for Conservation Research. “We are using science to refine translocation methods that we can use to ensure desert tortoises have the greatest chance for survival.”
In addition, data-collection devices have been set up in and around burrows in the desert to monitor temperatures. The conservation center’s staff will regularly check the tortoises so the GPS tracking devices can be recharged, said Yadira Galindo, a spokeswoman for the zoo.
The desert tortoise is on the federal list of imperiled species because of factors such as development reducing their natural habitat, increasing fire hazards and invasive plant species competing with native vegetation that tortoises eat, Galindo said. The herbivores, which weigh four to 11 pounds, eat small grasses, cactus flowers and other vegetation.
The conservation enter is home to about 3,000 tortoises, Galindo said. The animals are taken to the facility when they are sick, injured or found in unexpected places such as cities and backyards. Pets are often relinquished at the center and hatchlings that were born in urban areas, on private property or in public parks also are given to the center.