Two baby endangered bolson tortoises hatched at the Zoo earlier this year have been sent to the Turner Endangered Species Fund (TESF) in New Mexico. For many years the Zoo has supported TESF efforts to reintroduce bolson tortoises to desert areas in southern New Mexico. Our baby tortoises will be allowed to grow large enough to have the best chance to survive in the wild and then be released to support the overall conservation program.
The El Paso Zoo has been home to bolson tortoises for many years. According to the TESF website the population decline and contraction of the bolson tortoise range is due to climate change; habitat fragmentation, degradation and loss; and collection for food. Recent estimates suggest that fewer than 2,000 bolson tortoises remain in the wild. The Fund’s bolson tortoise recovery efforts have produced ~500 new bolson tortoises to date, thus contributing a significant boost to worldwide bolson tortoise numbers.
The overall goal is to establish independent, free-living, minimally managed bolson tortoise populations in the northern portion of the Chihuahuan Desert, which constitutes their prehistoric range. To this end, the aim is to increase bolson tortoise population size through robust captive breeding and head-start programs that protect juveniles until they reach a predator-resistant size. Juvenile bolson tortoises will be released on the Ladder and Armendaris Ranches to establish wild populations.
Wild Population Objectives
TESF will use the captive population to establish up to four wild bolson tortoise colonies on suitable private and/or public lands in the U.S. Each colony will have at least 250 adults and exhibit a male to female ratio of around 1:1, stable or positive population growth, and evidence of reproduction.
The starting point for the northern Chihuahuan Desert bolson tortoise reintroduction project was a group of 30 bolson tortoises that were collected and bred over a period of nearly 40 years by a private individual from Arizona. Successful breeding programs on the Armendaris Ranch in southern New Mexico and at the Living Desert Zoo and Gardens in Carlsbad have hatched over 400 juvenile tortoises since 2006.
Above – Hatchlings and juveniles are being kept on native forage in outdoor, predator-proof enclosures until they are large enough to be released.
Source – Turner Endangered Species Fund