Head to head
Sonoran Desert Tortoise vs Desert Tortoise
A Sonoran desert tortoise and a desert tortoise, often called the Mojave desert tortoise, were long treated as a single species until genetic and physical studies published around 2011 revealed enough separate evolutionary history to split them apart.
| Sonoran Desert Tortoise | Desert Tortoise | |
|---|---|---|
| Scientific name | Gopherus morafkai | Gopherus agassizii |
| Preferred terrain | Rocky desert slopes, bajadas | Flat desert basins, washes |
| Shelter type | Natural rock crevices | Self-dug burrows, several metres long |
| Range | Sonoran Desert, Arizona, NW Mexico | Mojave Desert, CA, NV, UT, AZ |
| Peak activity | Summer monsoon season | Spring, after seasonal rain |
| Conservation status | Vulnerable | Critically Endangered |
| Population trend | Decreasing | Down roughly 90% since the 1980s |
| Species split | Recognised as distinct in 2011 | Recognised as distinct in 2011 |
Sonoran Desert Tortoise vs Desert Tortoise: common questions
Why were the Sonoran desert tortoise and desert tortoise once considered the same species?
The two populations look broadly similar and were long treated as a single species, but genetic and physical studies conducted in the years leading up to 2011 revealed enough long-term evolutionary separation between them, reflected in differences like shelter behaviour and preferred terrain, to justify formally splitting them into the Sonoran desert tortoise and the Mojave desert tortoise.
Why is the desert tortoise so much more endangered than the Sonoran desert tortoise?
The Mojave desert tortoise has faced especially severe habitat loss from urban and solar-farm development, road mortality, disease spread partly by released pet tortoises, and a surge in raven predation on hatchlings fuelled by human food and structures, driving an estimated 90 percent decline since the 1980s, pressures that have hit the Sonoran desert tortoise's more rugged, less developed range somewhat less severely, though it remains a species of real conservation concern in its own right.
How do these two tortoises find shelter differently?
The Sonoran desert tortoise relies mainly on natural rock crevices and shelters within its rocky, mountainous terrain, while the desert tortoise digs its own extensive burrows, some several metres long, into the looser soil of the flatter desert basins it inhabits, a difference in shelter strategy that reflects the different terrain each species evolved in.