FOR IMMEDIATE RELEASE
CONTACT:
San Diego Zoo Wildlife Alliance
PublicRelations@sdzwa.org
sdzwa.org
Erin Scott
EScott@LivingDesert.org
livingdesert.org
NEWS RELEASE
San Diego Zoo Wildlife Alliance and The Living Desert Zoo and Gardens Report Juvenile Desert Tortoises are Thriving After Rescue from Heat Wave
To Improve Prospects for Survival, Young Tortoises Will Be Reared in Human Care Before Being Reintroduced into Native Habitat
SAN DIEGO and PALM DESERT, CALIF. (Sept. 30, 2022) – As a changing climate impacts wildlife around the globe, one keystone species in the Southwest United States serves as a prime example of the dangers of rising temperatures and habitat loss. This year, new hatchlings and eggs of desert tortoises—a species well adapted for harsh, high desert summers—were given an emergency evacuation when a recent intense heat wave in the region was putting them at risk. San Diego Zoo Wildlife Alliance transferred the juvenile tortoises from their outdoor headstarting habitats at Edwards Air Force Base to an indoor facility at The Living Desert Zoo and Gardens, where they will have a chance to grow before being reintroduced into native habitat.
Once common throughout the Mojave and Sonoran deserts of California, Nevada and Arizona, desert tortoise populations have declined by an estimated 90% in the last 20 years. California’s Mojave Desert tortoise, federally protected in the United States since 1989, is categorized as Critically Endangered on the International Union for Conservation of Nature (IUCN) Red List of Threatened Species, and faces threats including habitat loss and fragmentation, disease, human-subsidized predators and climate change. The U.S. Fish and Wildlife Service’s evaluation of population trends from 2018 indicate that the species is on a path to extinction under current conditions. The persistence of threats in combination with these trends indicates continued status deterioration in the absence of meaningful progress. San Diego Zoo Wildlife Alliance and The Living Desert are working in partnership with Edwards Air Force Base, the U.S. Fish and Wildlife Service and the U.S. Geological Survey, using headstart techniques designed to increase the survival rate for young tortoises. By tracking gravid (egg-carrying) desert tortoises, monitoring the adult females as they lay eggs in human care, and rearing hatchlings for one to two years in sheltered facilities, to be reintroduced to native habitat when they are no longer at their most vulnerable, conservationists are giving juvenile tortoises a fighting chance at survival.
“We are very fortunate to have the skill, the resources and the space to be able to care for these juvenile desert tortoises, and help them grow at a much faster rate than they would in the wild,” said James Danoff-Burg, Ph.D., director of conservation at The Living Desert Zoo and Gardens. “By rearing hatchlings safely inside and in human care, we’re reducing the risk of mortality during their most vulnerable stage, and ultimately giving these young tortoises a fighting chance when they are reintroduced into the wild.”
The desert tortoise hatchlings were scheduled to be moved to The Living Desert in October 2022, where they would stay indoors for several months before being transported back to the outdoor headstarting habitats at Edwards Air Force Base. The transfer took place a month earlier than expected because of emergency circumstances, caused by unrelenting heat. Young desert tortoises are unable to develop normally at nest burrow temperatures above 95.5 degrees Fahrenheit. Temperatures of 109.4 degrees Fahrenheit cause physiological impairment, and can be lethal to hatchlings. Upon emergence, hatchlings are still learning about the world, and may take some time to find preferred burrows. Because of their small size, their body temperatures quickly match environmental temperatures. Outdoor temperatures approached or exceeded 109.4 degrees Fahrenheit for more than 12 days in a row during the recent heat wave, and teams recorded temperatures in the shade approaching lethal range for hatchlings. It’s important to understand that this headstart facility is within the native range of desert tortoises, so tortoises in their original habitats likely face the same challenges.
Prior to making the move, extensive measures were taken to protect eggs and newly hatched tortoises, including shading nest burrows, misting water around burrow entrances to cool the substrate and adding many extra burrows. Ultimately, because the heat wave coincided with such a sensitive time in the desert tortoise life cycle, these efforts were not enough. In the face of the extreme temperatures, the partners made a collective decision to intervene. The eggs and hatchlings were excavated from their nests overnight when the weather was cooler. Eggs that were unhatched or in the process of hatching were placed in incubators at The Living Desert to ensure successful emergence.
Conserving this long-lived species is critical work, but climate change continues to create new challenges. San Diego Zoo Wildlife Alliance, The Living Desert, Edwards Air Force Base, the U.S. Fish and Wildlife Service and the U.S. Geological Survey are working to address the thermal ecology of desert tortoises, especially the youngest age groups, to better understand how a changing climate will impact the tortoises, and identify strategies to mitigate. For thermal preference studies, each individual hatchling needs to be exposed to the same thermal gradient, which is very difficult to do outdoors in the field.
“This collaboration with The Living Desert is especially important, because we have the opportunity to learn more about the thermal ecology of the youngest age class of desert tortoises while they are in an environment where the temperature is controlled,” said Melissa Merrick, Ph.D., associate director of recovery ecology at San Diego Zoo Wildlife Alliance. “Heat waves are a normal part of life in the desert, but their frequency, duration and severity are projected to increase with climate change. We need to know how this age class will be impacted, especially when they are at their most sensitive.”
Research led by San Diego Zoo Wildlife Alliance since 2009 has identified key factors influencing successful reintroduction of tortoises, including important natural resources and habitat features, predator evasion strategies, foraging behavior, individual characteristics and more, ultimately helping to improve reintroduction protocols. Long-term monitoring of released tortoises is underway using transmitters to track their behavior over time, as well as new projects that identify critical habitat features. Gaining a better understanding of the relationship between tortoises and their habitats allows conservationists to prioritize areas for preservation and set goals for restoration of degraded lands.
Desert Tortoise Week 2022, hosted by the U.S. Fish and Wildlife Service, will take place the first week of October. The Living Desert, joined by San Diego Zoo Wildlife Alliance, will hold a free webinar on Monday, Oct. 3 at 11 a.m. PT to discuss their collaborative desert tortoise conservation work and provide attendees with a special look at the rescued hatchlings. Tune in: https://us02web.zoom.us/webinar/register/WN_FLp8t71KTiaTARpMtrMUbQ
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About San Diego Zoo Wildlife Alliance
San Diego Zoo Wildlife Alliance is a nonprofit international conservation leader, committed to inspiring a passion for nature and creating a world where all life thrives. The Alliance empowers people from around the globe to support their mission to conserve wildlife through innovation and partnerships. San Diego Zoo Wildlife Alliance supports cutting-edge conservation and brings the stories of their work back to the San Diego Zoo and San Diego Zoo Safari Park—giving millions of guests, in person and virtually, the opportunity to experience conservation in action. The work of San Diego Zoo Wildlife Alliance extends from San Diego to strategic and regional conservation “hubs” across the globe, where their strengths—including the renowned Wildlife Biodiversity Bank—are able to effectively align with hundreds of regional partners to improve outcomes for wildlife in more coordinated efforts. By leveraging these tools in wildlife care and conservation science, and through collaboration with hundreds of partners, San Diego Zoo Wildlife Alliance has reintroduced more than 44 endangered species to native habitats. Each year, San Diego Zoo Wildlife Alliance’s work reaches over 1 billion people in 150 countries via news media, social media, their websites, educational resources and San Diego Zoo Wildlife Explorers television programming, which is in children’s hospitals in 13 countries. Success is made possible by the support of members, donors and guests to the San Diego Zoo and San Diego Zoo Safari Park, who are Wildlife Allies committed to ensuring all life thrives.
About The Living Desert Zoo and Gardens
The Living Desert Zoo and Gardens is a nonprofit, accredited member of the Association of Zoos and Aquariums, ensuring the highest standards of all aspects of animal care, education, conservation, public service, and operations. The Zoo is active in conservation research, habitat protection, breeding programs and education initiatives around the world, as well as in its own community. The Zoo has been a top destination in the Palm Springs area for more than 50 years. The Living Desert is located at 47900 Portola Ave, Palm Desert, CA 92260. For more information: (760) 346-5694 or visit livingdesert.org.
