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FE ATURE Testing the Waters in the Desert: Establishing a Bolson Tortoise Colony Where Bolson Tortoises Haven’t Tread in over 10,000 Years Their scientific name, flavomarginatus, meaning “yellow-margined”, describes how Bolson Tortoises have yellow marginal scutes with most individuals also displaying yellow toenails. Known as the “Tortuga Grande” and the “Running Tortoise”, their propensity for a running take off to the nearest burrow distinguishes them from other tortoises who are more likely to stay put and retreat into their shells. Adult male Bolson tortoises like the one shown here are generally smaller than the adult females (by ~15%). The largest of the males in our colony have shell lengths of ~325 mm, the largest females reach ~390 mm. PHOTO CREDIT: SCOTT HILLARD In 2006, the Turner Endangered Species Fund (TESF) accepted responsibility for a group of tortoises collected and bred since the early 1970s by the late Ariel Appleton. In the summer and fall of 2006, TESF staff and volunteers rounded up Ariel’s tortoises near Elgin, Arizona, and transferred them to their new home on the Armendaris Ranch in southern New Mexico. The Armendaris, owned by media mogul and Christiane Wiese and Scott Hillard conservationist Ted Turner, lies at the northern tip of the tortoise’s prehistoric range in the Chihuahuan Desert. Largest of the five North American tortoise species, the Bolson Tortoise (Gopherus flavomarginatus) is believed to have once roamed throughout most of the Chihuahuan Desert. The tortoises’ current range is now restricted to the small “Bolson de Mapimi” area in north central Mexico. BREEDING PROGRAM SUCCESS We’ve developed a robust breeding program on the Armendaris Ranch over the last 9 years; resulting in over 500 new Bolson Tortoises. Young tortoises are housed in outdoor holding pens to protect them from predators until they are large enough to fend for themselves. What it precisely means scientifically for them to be “large enough” is a research question still under investigation. In the fall of 2012, we began outfitting larger juveniles (>100 mm shell length; between four and seven years old) with transmitters and moving them from the protected pens to large (7.5 hectare) unprotected, predator-accessible enclosures fenced to comply with current permit requirements, but not covered. Because of such releases, over 100 captive born tortoises experience life as wild animals with minimal human interference. We weigh, measure, and assess health twice a year. Beyond that, the tortoises are on their own. Survivorship is an astounding 85 percent. Predators known to eat tortoises, such as ravens, roadrunners, hawks, ground squirrels, ringtails, raccoons, coyotes, mountain lions, bobcats, bears, and snakes are present on the Turner Ranches, but may pass up the Bolson Tortoise ‘tortellinis’ for more accessible prey. Bolsons spend upwards of 90 percent of the time in their burrows, and generally emerge only for basking sessions close december 2015 42 turtle survival
official population count was conducted in the early 1980s. Even then, the wild population was thought to comprise a mere 8,000 to 10,000 animals existing in six separate colonies. One of these colonies was protected inside the Mapimi Biosphere Reserve, but the continued threats of habitat degradation and human consumption are likely to have significantly reduced the number of wild Bolson Tortoises. Fewer than 2,000 adults are estimated to remain in the wild today. There is good news from other quarters. Given the current rates of reproduction of our semi-captive colony on the Turner Ranches, the U.S. population of Bolson Tortoises may soon rival the size of the wild population. Dr. Jim Jarchow watches as a juvenile tortoise with transmitter slowly advances to check out the burrow the tortoise team has chosen for its release in the large unprotected pen. This Bolson Tortoise juvenile was the 100 th tortoise released to live as a wild tortoise in the northern portion of its species’ prehistoric range with minimal human support or interference. PHOTO CREDIT: CHRISTIANE WIESE Coaxing an adult tortoise out of its burrow requires getting up close (or down close, as the case may be) and personal. Here, one of the authors is patiently taking advantage of the tortoise’s natural behavior to defend its burrow by pretending to be an intruder. In most cases, the tortoise’s efforts to evict the intruder will eventually bring it close enough to the burrow entrance to be captured. PHOTO CREDIT: SCOTT HILLARD to the security of the burrow opening. They’re out for relatively brief foraging bouts, so unless it rains, young tortoises are rarely encountered away from their burrows. WILD POPULATION STATUS UNKNOWN Little is known about the current status of the Bolson Tortoise in the wild. The last MOVING BEYOND ASSURANCE COLONIES TESF’s ultimate goal is to move beyond maintaining captive assurance colonies, and establish free-ranging populations in what was the Bolson habitat before early humans greatly reduced their range, and modern humans brought them close to the brink of extinction. Monitoring the growth and fecundity of our colony has convinced us that Bolson Tortoises not only survive, but actually thrive in the northern Chihuahuan desert grasslands. About half of our 13 females routinely triple clutch, and clutch size is similar to wild counterparts. Moreover, released juvenile tortoises find enough high quality, native forage to manage normal growth rates. What remains to be established is whether nests and hatchlings in unmanaged or minimally managed populations can survive at rates high enough to maintain and increase the population. Concerns about future landscapes, in the face of inevitable climate change, prompt careful consideration of potential reintroduction sites. In addition to establishing free ranging, minimally managed Bolson Tortoise populations on Turner lands, we envision them once again roaming the desert shrublands of places like Big Bend National Park. Many thoughtful conversations will need to take place to fully address lingering concerns about reintroducing a species not present in a region since before the time of Christopher Columbus. But hopes are that truly wild Bolson Tortoises will once again tread on northern, public Chihuahuan Desert lands. Contacts: Christiane Wiese, Turner Endangered Species Fund, Ladder Ranch, HC 31 Box 95, Caballo, NM 87931, Chris.Wiese@retranches.com; Scott Hillard, Department of Ecology and Evolutionary Biology, 621 Young Drive South, UCLA, Los Angeles, CA, USA 90095-1606, hillard@earthlink.net See also www.tesf.org. Acknowledgements: We thank our partners for their support: Living Desert Zoo and Gardens State Park (Carlsbad, NM), El Paso Zoo (El Paso, TX), and San Antonio Zoo (San Antonio, TX). We are grateful to the many volunteers who have helped over the years, especially our trusted provider of veterinary care, Dr. James Jarchow, DVM (Tucson, AZ). a publication of the turtle survival alliance 43 visit us online at www.turtlesurvival.org
Page 1 and 2: Turtle Survival A PUBLICATION OF TH
Page 3 and 4: TURTLE SURVIVAL ALLIANCE Board of D
Page 5 and 6: ANIMAL MANAGEMENT TURTLE SURVIVAL C
Page 7 and 8: KEEPING TRACK OF RESIDENTS AND NEW
Page 9 and 10: ANIMAL MANAGEMENT Making Connection
Page 11 and 12: The Hatchling Room received a much-
Page 13 and 14: GENEROSITY IN THE LOW COUNTRY Natha
Page 15 and 16: The Turtle Survival Center (TSC) pr
Page 17 and 18: CONSERVATION NOTES Turtle Biology a
Page 19 and 20: Dina workshops in two districts: Ts
Page 21 and 22: Winning Hearts - and Respect for Ra
Page 23 and 24: RANGE COUNTRY UPDATE INDIA througho
Page 25 and 26: Adult male Northern River Terrapins
Page 27 and 28: were marked and released at the pre
Page 29 and 30: The large pond in the foreground wa
Page 31 and 32: in captivity, we initiated an exper
Page 33 and 34: lax to non-existent for many years.
Page 35 and 36: RANGE COUNTRY UPDATE INDONESIA more
Page 37 and 38: needed to facilitate egg fertilizat
Page 39 and 40: Announcing the 2nd Hicatee Conserva
Page 41 and 42: Additionally, a survey determined o
Page 43: In the field, water filtration usin
Page 47 and 48: although very low levels of illegal
Page 49 and 50: measures since 2006. In 2007, KFI
Page 51 and 52: FE ATURE TSA Develops Blueprint for
Page 53 and 54: Table 1. Species chosen by the TSA
Page 55 and 56: TSA PARTNER NEWS TURTLE CONSERVATIO
Page 57 and 58: TSA EUROPE Cuc Phuong National Park
Page 59 and 60: TSA EUROPE MUENSTER ZOO Successful
Page 61 and 62: and groups - especially if I feel I
Page 63 and 64: I heard about TSA from Scott Pfaff,
Page 65 and 66: TRYON FUND UPDATE Tryon Bog Turtle
Page 67 and 68: species. Somewhere along the way we
Page 69 and 70: a publication of the turtle surviva
Page 71 and 72: DONOR RECOGNITION Thank you for you

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