What it means
The desert tortoise is the slowest celebrity in the Sonoran Desert: a high-domed, sand-colored land turtle the size of a mixing bowl, eight to ten pounds when grown, that spends most of its life underground and comes out to graze after rain. In Arizona it is a distinct species, the Sonoran desert tortoise, and it lives on rocky slopes and in boulder piles, the kind of ground the McDowell Sonoran Preserve is made of.
Locals use the word in two quite different situations. One is the trail, where a tortoise crossing in front of you in August is a lucky, quiet moment you should not interrupt. The other is the backyard: plenty of Scottsdale families have a state-owned tortoise living under the oleanders, adopted from Arizona Game and Fish, and the kids have named it something like Speedy. The desert wildlife field guide puts the rule for the first case simply: you are the visitor.
Where you’ll meet it
On rocky Preserve slopes after summer storms, from the monsoon into fall; and in neighborhood yards, where adopted tortoises dig in for winter and reappear in spring. The kids guide has the family outings where a sighting is a bonus.
Where the word came from
“Desert tortoise” is plain description, and for almost 150 years it covered every tortoise in the Mojave and Sonoran deserts as one species, Gopherus agassizii, named for the naturalist Louis Agassiz. Genetic work changed that in 2011, when Robert Murphy and five colleagues described the tortoises south and east of the Colorado River as a separate species, Gopherus morafkai. The name honors David Joseph Morafka, a California State University, Dominguez Hills professor who spent his career on the genus. The Mojave animal kept the old name and is now Agassiz’s desert tortoise; Arizona’s is Morafka’s, or simply the Sonoran desert tortoise.
The split matters because the two live differently. Mojave tortoises are spring animals of open valley flats. Sonoran tortoises live on steep, rocky slopes among palo verde and saguaro, often on grades over 40 percent, and do most of their living in late summer and fall when the monsoon greens up the annuals they eat. A tortoise in a Scottsdale wash in August is behaving exactly as its species should.
What it is not
Not a box turtle and not a pond turtle; it is a strictly land animal of dry, rocky ground. And not the African sulcata, the big pet-store tortoise that grows far larger than any native; if a “desert tortoise” is the size of an ottoman, it is a sulcata.
The fine print
The law is strict. Arizona has protected wild desert tortoises since 1987: they may not be collected from the wild, imported or exported without specific permission from Game and Fish. The species is not federally listed under the Endangered Species Act, but the state treats it as a species of concern, and the IUCN lists it as vulnerable. The Forest Service names its threats: fire, invasive buffelgrass, illegal collection, habitat fragmentation and disease carried by captive tortoises released into wild populations.
That last threat is why the Tortoise Adoption Program exists. Captive tortoises, many of them the offspring of illegal backyard breeding, cannot be released, so Game and Fish places them with Arizona residents. Adopters get one tortoise per household, with a second of the same sex allowed in a separate enclosure, and the animal remains a ward of the state; move out of Arizona and it goes back, because federal law bars carrying the species across state lines. The program’s manager has said more desert tortoises now live in captivity than in the wild. In Tucson, the Arizona-Sonora Desert Museum runs a sanctioned program of its own.
Biology explains the patience required. Sonoran females mature at about 15 or 16 years and lay a single clutch of roughly four to six eggs a year. Game and Fish says a desert tortoise can live more than 80 years, which makes an adoption less like getting a pet and more like inheriting a relative. The McDowell Sonoran Conservancy’s survey found the species among 35 reptiles and amphibians on the Preserve, alongside the Gila monster.