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Rewilding the Bolson Tortoise to the American Southwest

Project Details:

Beneath the sun-baked deserts of New Mexico, the Turner Endangered Species Fund (TESF) is bringing back a prehistoric relic—the Bolson Tortoise (Gopherus flavomarginatus). Once, these gentle giants lumbered across desert grasslands from the American Southwest into Mexico. Climate shifts and human pressure led to its vanishing from its United States range over 10,000 years ago. Today, the Bolson tortoise is listed as Critically Endangered, with a global wild population numbering less than 2,500 animals. Since 2006, TESF has been leading managed breeding and headstarting efforts, raising the first U.S.-born Bolson tortoise in 10,000 years, and begun releasing young tortoises onto vast, predator-managed grasslands.

In Partnership With

Every year, countless species and ecosystems disappear. In 1997, Ted Turner, his family, and Mike Phillips created the Turner Endangered Species Fund (TESF) and Turner Biodiversity Divisions (TBD) to fight this loss. TESF focuses on legally protected species; TBD supports those at lower risk. Together, they work to restore and sustain wildlife—especially on private lands—through partnerships with agencies, universities, and NGOs. Their goal: self-sustaining populations that reflect healthy, functioning ecosystems. Despite challenges, they remain a committed force against extinction.

Why the Bolson Tortoise Matters

The Bolson tortoise is a living fossil and a keystone engineer: its deep burrows trap moisture, moderate soil temperatures, and create shelter for countless desert reptiles, mammals, insects, and plants. Restoring this ancient herbivore jump-starts ecosystem functions lost since the late Pleistocene.

Progress So Far

TESF’s efforts have already made history. The project has successfully bred and released the first U.S.-born Bolson tortoises in over 10,000 years. Over 150 tortoises are now roaming free on Turner’s ranches in New Mexico. These successes prompted the U.S. Fish and Wildlife Service to launch a formal recovery program—a rare step for endangered species. The project’s focus on private lands highlights TESF’s critical role in conservation, while its Pleistocene rewilding approach is reshaping how we think about ecological restoration.

How the Species Reintroduction Fund is Helping

With support from the Colossal Foundation, the project will take critical steps in 2025:

  • Juvenile Release – Rewild 40 juvenile tortoises from breeding programs to bolster wild populations.

  • Monitoring – Track over 150 free-ranging tortoises to gather vital data on movement, growth, and survival.

  • Shared Science – Publish rewilding protocols and data that guide U.S.–Mexico recovery planning and inform global herpetofauna reintroductions.

  • Long-Term Vision: Lay groundwork for five viable populations by 2035 to ensure species’ survival.