California’s Mojave desert tortoises move toward extinction. Why saving them is so hard
Mojave desert tortoises have been classified in the federal endangered species list since the 1990s. The Mojave desert tortoise is one of the smallest in the western hemisphere, with a maximum weight of only eight pounds. Photo: Courtesy of the U.S. Fish and Wildlife Service, California Department of Fish and Wildlife
By the numbers
There are several versions of how much the Mojave tortoise population has declined. These figures come from a number of sources, including reports by the U.S. Fish and Wildlife Service, the National Marine Fisheries Service, the Monterey Bay Aquarium Research Institute and the California Department of Fish and Wildlife.
According to the Fish and Wildlife Service, the population in the Mojave has fallen by as much as 75 percent in the first decade of the 21st century, and by about 92 percent in the last decade.
According to the Monterey Bay Aquarium Research Institute, the population has fallen by 95 percent in the first decade of the 21st century, and by about 98 percent in the last two decades.
According to the California Department of Fish and Wildlife, the population has fallen by about 70 percent in the first decade of the 21st century, and by about 90 percent in the last decade. This is the agency’s most recent assessment for the Mojave desert tortoise.
The Fish and Wildlife Service report says the population in the Mojave has declined by 77 percent since 1975. But the agency says there’s disagreement about exactly which years that is, because it counts tortoises found in different parts of the state.
When you add these figures to what the tortoise population has been doing in the 1970s and ’80s, where it was still quite large, then it becomes clear that the decline is quite dramatic. It is the kind of decline that can’t be explained by habitat loss, changes in land use or any other natural phenomena. It’s caused by the intentional destruction of habitat.
This has been a trend since the 1990s. And the decline is expected to continue into the 2020s, perhaps leading to extinction.
But there is one reason the extinction rate, or the number of the animals per unit area, is accelerating. That is because the Mojave desert tortoise is the species most dependent on its habitat. Tortoises don
