The Bolson tortoise (Gopherus flavomarginatus), also called the Mexican giant tortoise or yellow-margined tortoise, is a species of tortoise from North America. Of the six North American tortoise species, it is the largest, having a carapace length of about . It lives in a region of the Chihuahuan Desert known as the Bolsón de Mapimí, which is located in north-central Mexico. Discovery The Bolson tortoise was discovered only in 1959. The legend is that a group of biologists working in the Bolsón de Mapimí were at a ranch and saw chickens eating out of a large tortoise shell. They inquired about the origin of the shell and the locals responded by saying that it was, "la tortuga grande del desierto", the big turtle of the desert. In 1979 the 340,000 hectare Mapimi Biosphere Reserve was created to protect the Bolson tortoise and other unique flora and fauna of the Bolsón de Mapimí. Despite this designation, cattle ranching and mining still occur in the reserve. Whether this is detrimental to the tortoise is not known. Declining population The most recent research, published in 1991 from data collected in 1983, estimates that fewer than 10,000 tortoises remain in the wild. Populations have declined mostly due to overcollecting for food and the pet trade. Incursion of roads, railroads and agricultural development have accelerated the decline of the species in the last 40 years. In the central portion of its range locals are keenly aware of the tortoise's protected status and aid in its conservation. However, in the northeastern portion of its range, near La Sierra Mojada, populations of the tortoise are low. It is believed that tortoises are still collected and eaten in this area. Additionally, extensive brush clearing operations are being conducted to make way for cattle grazing. In 2008, following the construction of federally subsidized ethanol plants, extensive corn farming operations began within the Mapimi Biosphere Reserve. Farms have been tilled in tortoise habitat, despite its protected status. In 2018, the IUCN Tortoise and Freshwater Turtle Specialist Group recommended a re-assessment and re-classification of all six Gopherus species. This reclassification would move G. flavomarginatus from Vulnerable (VU) to Critically Endangered (CR) Appleton tortoises In the fall of 2006, 26 Bolson tortoises were translocated from the Audubon Appleton-Whittell Research Ranch in Elgin, Arizona to Ted Turner's Armendaris Ranch in south-central New Mexico, a Chihuahuan desert environment within the prehistoric range of this