Animal Conservation: Technology Tracking Threatened Tortoises
A Mojave desert tortoise set her sights on eating a cactus bloom immediately after being released into the desert by Paula Kahn, Ph.D., a San Diego Zoo Institute for Conservation Research scientist. The tortoise was one of 36 tortoises relocated from the Desert Tortoise Conservation Center to protected desert land south of Las Vegas on Wednesday. Each tortoise wears a VHF transmitter the size of a small stack of quarters. In addition, this and 23 of those animals also carry GPS units that will provide detailed data about the animals' movements and habitat choices. Scientists will track the tortoises to gather detailed data that will be used to refine translocation methods as part of a desert tortoise recovery program. Photo by Ken Bohn, San Diego Zoo.
It was an odd site in the Mojave desert, not just because 36 tortoises were being toted around in clear plastic containers, but because each of these animals carried on its shell a piece of technology that will make it easier for San Diego Zoo Institute for Conservation Research scientists to track their movements. Each tortoise carries on its back a VHF radio transmitter the size of a small stack of quarters. An antenna protrudes from the circular device making it look more like an armored vehicle.
As I walked through the desert alongside the scientists I was roped into helping carry one of the plastic containers. After walking some 500 meters in the heat of the desert just south of Las Vegas, my arm was getting tired, but it was a worthwhile occurrence that not many people are able to experience. The tortoises weighed between 4 to 10 pounds, I’m pretty sure I got the 10 pounder. The animals didn’t move much while we carried them to their final destination, a spot determined by the scientists carrying a GPS unit. Each tortoise had a precise location it would be released in. The only variable was which cactus or shrub to set it under for shade.
Watch the video and listen to Dr. Kahn speak about this program here: http://bcove.me/o00x40th
No tortoise is handled with bare hands. The scientists would place clean surgical gloves on each hand for each tortoise they touched. They were being careful not to transmit any disease to these very important creatures. The 36 tortoises are the subject of a scientific study to gather data about desert tortoise movement and habitat choices. The VHF transmitters will help the team find the tortoises in the desert but the GPS units that 24 of these tortoises also carry on their shells will provide detailed data about the animals’ movements and their preferred environment. In conjunction with data collectors set up inside and outside of burrows that provide the temperature and humidity readings, the Zoo team will be able to determine the best conditions into which the tortoises should be released.
The Mojave desert tortoise is a threatened species. Its population has declined due to habitat degradation and the loss of their home territory. Construction continues to expand into the desert and introduced exotic plant species have replaced native vegetation that the tortoises depend on for food and shelter. In addition, nonnative grasses have increased wildfire risks devastating not just the tortoises but other species. On this day I saw a variety of small reptiles, insects, jack rabbits and squirrels.
The desert tortoise is a protected species under federal and state laws. It is illegal to collect them from the wild and illegal to release them to the wild. People do have them as pets but legally the can only be acquired through an adoption program approved by the U.S. Fish and Wildlife Service. The tortoises released by the San Diego Zoo are part of a collaborative partnership with U.S. Fish and Wildlife Service, the U.S. Bureau of Land Management and the Nevada Department of Wildlife in 2009 to operate the Desert Tortoise Conservation Center. Since joining this partnership, the Zoo added veterinary services to diagnose and treat tortoises on site, modified enclosures to add space for quarantine and create predator-proof hatchling pens, established bio-security and processing protocols, began outreach to surrounding communities and tortoise custodians, doubled its full-time staff, implemented conservation research projects, and is operating the pet desert tortoise pick-up service.
These very special tortoises were released as part of a long-term recovery program aimed at helping the tortoise rebound. Thousands of tortoises live at the Desert Tortoise Conservation Center in Las Vegas. After rehabilitation and some TLC the hope is that most of them will end up back in the desert, but we know that will not happen for all of them. They have to be healthy and strong to make it on their own and some tortoise arrive injured or too sick to ever be released. In addition, the desert must also be healthy to carry the weight of these 10 pound tortoises. It was clear how important the plant life is to the tortoises. The moment one tortoise was set down in her new desert home she headed directly for the bloom of a cactus. The beautiful flower became this tortoise’s first meal as newly wild tortoise.
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