The Heat is On: Desert Tortoises and Survival

Though the Mojave Desert tortoise has thrived in the southwestern United States for thousands of years, its population has severely declined over the last four decades. A new USGS documentary, titled The Heat is On: Desert Tortoises and Survival, explains why this important indicator of desert ecosystem health is declining and what scientists are doing to save them. Mojave tortoises were first listed as a threatened species in 1990. Widespread and rapid declines in tortoise numbers have made them a top priority for federal research and are driving efforts to recover the species. The desert tortoise will not be removed from the endangered species list until its population stabilizes or increases over 25 years. “Scientific research about the tortoise population across the entire Mojave Desert allows us to put together a more complete picture of the tortoise’s habitat needs and reasons for its decline,” said Todd Esque, USGS research ecologist, who is featured in the documentary. “Researching the decline of this reptile can tell us a lot about the overall health of the desert.” Declines are due to habitat loss associated with urban development, utility corridors, highway mortality, off-road vehicle use and recreational activities. Also, populations of predators like coyotes and ravens have grown exponentially, subsidized by human food sources. Power lines provide artificial nesting perches for ravens, and invasive plant species compete for scarce resources and fuel fires that destroy the habitat. Diseases, such as upper respiratory tract disease, have also played a major role in tortoise declines...read more