The Bolson tortoise (Gopherus flavomarginatus) is the largest of the four North American tortoise species and was first described as a distinct species in 1959 (Legler 1959).  Evidence suggests that this species was distributed throughout the Chihuahuan Desert (Map 1) until the late Pleistocene (Donlan et al. 2006).  Through anthropogenic factors and habitat loss, Bolson tortoises experienced severe population declines and range contraction, with relict populations today restricted to a small area (~10 km²) in north central Mexico.  Population surveys conducted in the 1980’s estimated fewer than 8,000 extant individuals.

In 2004, Drs. Jane and Carl Bock of the University of Colorado enquired whether TESF might accept a group of captive bolson tortoises for the purposes of conservation.  These captives (the "Appleton tortoises") lived at the time in outdoor enclosures at the Appleton Research Ranch in southeaster Arizona (Map 1).  In 2006, 30 captive bolson tortoise adults were transferred to the northernmost portion of the tortoise’s prehistoric range.  26 of these adults were taken to the Armendaris Ranch, NM, and the remaining 4 were housed at the Living Desert Zoo in Carlsbad, NM.  Under the auspices ofTESF, a plan was developed to establish a breeding program and determine whether a self-sustaining population of bolson tortoises could be successfully reintroduced to the New Mexico landscape (Figure 1) in an effort to contribute to the conservation of this species.