Blog: Helping Out the Radiated Tortoises in Madagascar

by Maris Brenn-White, DVM, MPVM, Research Fellow, Saint Louis Zoo Institute for Conservation Medicine

May 23 is World Turtle Day — a day to celebrate and commit to protecting the amazing, unique and diverse turtles and tortoises that share our planet. At the Saint Louis Zoo, we work with many colleagues to find and enact conservation solutions for turtles and tortoises around the world. I am excited to tell you about our newest collaboration and recent fieldwork to help the recovery of the critically endangered radiated tortoise (Astrochelys radiata). Saint Louis Zoo participation in this work was made possible through a Saint Louis Zoo WildCare Institute Field Research for Conservation grant and financial support by the Saint Louis Zoo Institute for Conservation Medicine, WildCare Institute Center for Conservation in Madagascar, and Saint Louis Zoo Department of Animal Health.

The Tortoises

The radiated tortoise is an iconic species of Madagascar that lives only in the spiny forest in the southern part of the island. Radiated tortoises were once found in large numbers throughout their range, but their populations have plummeted to such an extent that, without intervention, they could be extinct in the wild within 45 years. Illegal collection for the pet trade and, in smaller quantities, for food, is a main cause of this decline. Roughly 24,000 radiated tortoises destined primarily for the illegal pet trade have been confiscated in recent years and are currently cared for by the Turtle Survival Alliance (TSA). In preparation for the first large scale release of these tortoises back into the wild, I traveled to Madagascar in February 2020 to provide on-the-ground veterinary support for pre-release health assessments and to conduct health research to assist future rescue, rehabilitation, and release efforts.

(Click photos to see slideshow and captions)

Getting to Madagascar

Upon arrival in the capital city of Antananarivo, I met up with Jane Merkel, Saint Louis Zoo Department of Animal Health Zoological Manager and veterinary technician. We wended our way through customs, which is always an interesting experience carrying a liquid nitrogen tank and a large duffel bag full of veterinary supplies. At Turtle Survival Alliance headquarters, we gathered with the rest of the health team: Dr. Ny Aina Tiana Rakotoarisoa (veterinarian, TSA), Dr. Bonnie Raphael (veterinarian, TSA and Wildlife Conservation Society Zoological Health Program), Dalia Ferguson (veterinary technician, Wildlife Conservation Society Zoological Health Program), and Tony Ralivaniaina (veterinary student, TSA). Another plane ride and an 8-hour drive later, we arrived at TSA's Tortoise Conservation Center (TCC) much better acquainted.

Spiny Forest

The Turtle Conservation Center consists of several acres of spiny forest and is home to roughly 9,000 confiscated radiated tortoises. It would also be our home, office and laboratory for the next 16 days. Just as with the radiated tortoise, the spiny forest only exists in southern Madagascar. It is beautiful, mesmerizing, and is, itself, endangered. In February, it was also hot. After a few moments of taking in our new surroundings, we got to work setting up a lab in the on-site veterinary clinic and gathered with Christel Griffioen (TCC Manager), Riana Rakotondrainy (Lead Keeper), and TCC staff to strategize for the coming days.

Veterinary Work

To ensure that healthy tortoises are selected for release, we needed to provide veterinary exams to over 1,000 tortoises and process a suite of biological samples from a subset of these. We started work in the enclosures at 6 a.m. each morning to make the most of the cool hours of the day. With help from Tony, animal keepers Vontsoa and Mena did the hard work of gathering tortoises from throughout the expansive enclosures. Every tortoise received a physical exam by one of the veterinarians on the team, which grew to include Dr. Paul Calle (veterinarian, Wildlife Conservation Society Zoological Health Program) partway through the trip. Roughly 140 of tortoises also had blood drawn for standard bloodwork, oral and cloacal swabs taken for infectious disease testing, and feces collected to look for parasites, if a tortoise was kind enough to offer it. Taking our cues from the tortoises, when they started to take shelter from the heat of the day, we returned to the shade of the clinic to process samples.

Field Lab

Back at the clinic, Jane and Dalia led an efficient field lab, centrifuging blood to look for anemia, counting white blood cells to evaluate immune function, and analyzing blood chemistries to assess organ function and other measures of health. With these test results, we were able to take an in-depth look at the health status of a number of the tortoises. To improve future rescue, rehabilitation, and pre-release health assessments, we will also use these results to determine which test methods will give the best results in field conditions and what results veterinarians may expect to see in healthy radiated tortoises.

In the late afternoon, the technicians kept going at the microscopes while the rest of us headed back out for a second round of exams until both tortoises and humans were ready to call it quits for the day. On most evenings, I would look up while scrubbing the red dirt from my hands and see the resident troupe of ring-tailed lemurs sipping water from the tortoise basins outside the clinic and feel the heat and fatigue just wash away.

Preparing for Release

The ultimate goal of this effort is to allow confiscated individuals to return to the wild where they can reverse the population declines that put the radiated tortoise on the endangered species list. While lab work is ongoing and a small number of the tortoises did not meet release criteria, our team identified over 1,000 tortoises fit for release based on physical exams. Much more work needs to be done to prepare these tortoises for release and to create safe places for them to flourish, but one important piece of the puzzle has been completed.

I am grateful to have had the chance to join this team of bright, resourceful, and committed professionals and to have contributed to the success of these radiated tortoises as they are released back into their wild homes in the months and years to come.