Tortoises

The 2015 Expedition to Wolf: Next Steps Toward Repopulating Pinta and Floreana Islands

January 18, 2016

It’s been fun reading the blogs from various Wolf Expedition participants. I remained in the mountains of California while they wandered the slopes of the volcano; but with all the stories and photos, I almost feel like I was there. I certainly was in spirit. As coordinator of the Giant Tortoise Restoration Initiative (GTRI), I would now like to lay out where this exciting project is headed. Thirty-two saddleback tortoises are now being held in corrals at the Fausto Llerena Tortoise Center on Santa Cruz — waiting for genetic analyses. Amongst the several thousand native Wolf tortoises and many hybrid tortoises on Wolf Volcano, another 148 saddleback tortoises there now have a brand new microchip under the skin of their back leg. Blood samples from all 180 tortoises (32 in captivity and 148 on the slopes of Wolf) are ready to be shipped north to Yale University (awaiting the appropriate paper work), where Gisella Caccone and her team will begin the process of determining just what tortoise species are represented in their DNA.

As 2016 marches on, the tortoises’ DNA will begin to reveal the secrets of 200 years of tortoise reproduction on Wolf Volcano. Within the next six months, we should have a general idea of the ancestry of each tortoise. Then with a more refined methodology, we will find out how much of each tortoise’s genome is from one of the extinct species, as well as how much overall genetic diversity has been captured within the identified Pinta or Floreana genomes. Based on these results, the geneticists will recommend exactly which of the 32 tortoises should be used to initiate the breeding program — including which males should be matched with which females — to ultimately capture the highest possible level of Pinta or Floreana genomes and the highest genetic diversity in the offspring produced. Over time, this will involve a lot of tortoise matchmaking, guided by computer simulation.

The Galapagos National Park Directorate (GNPD) working with the scientists of the GTRI from Galapagos Conservancy, Yale, SUNY, etc., will then initiate a highly targeted breeding program, with the long-term goal of restoring the Pinta and Floreana tortoise populations. The program may begin with only a few pairs for each population; it all depends upon the results of the genetic analyses. These tortoises will be held under the same general conditions as the fifteen Española tortoises, which have been successfully reproducing in captivity for over fifty years to slowly repopulate that island. Our Tortoise Center review in November 2014 resulted in improvements to the programs and facilities; we, along with the GNDP, are dedicated to ensuring that all captive tortoises remain fit and healthy.

Pinta Island

You might ask: What about those tortoises with lower percentages or lower diversity of the target species? Rather than incorporate them into the breeding program, they will likely be released directly onto either Floreana or Pinta Islands. If any of the 32 tortoises show other ancestries (there is quite a mix of tortoises on Wolf Volcano, from more of the islands than just Pinta and Floreana), we will make tortoise-specific recommendations to the GNPD on whether to return them to Wolf Volcano or release them on some other island. If analysis of the samples from the 148 tortoises left on Wolf Volcano identify high value tortoises (with a high percentage of Pinta or Floreana genome and high diversity within that), we will work with the GNPD to carry out additional trips to Wolf to collect those animals, and potentially collect new unmarked animals with a similar saddleback shell shape.

If these tortoises are even better choices for the breeding program, adult tortoises already in the program might then be released onto Pinta or Floreana. Every time we change the breeding pairs to improve the level of the targeted genomes, we also increase the overall genetic diversity, moving at a tortoise pace toward a better outcome. But the work doesn’t stop there. As the tortoises begin to reproduce, we will want genetic analyses of the offspring. The majority of these young will be released onto their target island. However, if some have unusually high percentages of the target genome, they might remain in captivity to eventually be incorporated into the breeding program. This work is long-term and involves constant decision-making as the genetics of more and more tortoises are evaluated and that information is incorporated into the system. That’s part of what makes it so exciting.

Floreana Island

You might ask: Why not just release all of the tortoises collected from Wolf directly onto Pinta or Floreana — let nature take its course? We consider captive breeding combined with direct releases to be the optimal approach. Captive breeding will allow us to recapture as much of the original genes of the Pinta and Floreana tortoises as possible — to enhance their restoration on their home island. The decision to establish a captive breeding program and rear the young to 4-5 years before releasing them into the wild is directly related to survival of the young. In captivity, nearly all tortoises that hatch survive. By rearing them to 4-5 years old before releasing them, they have more than a 50% chance of surviving to adulthood. But in the wild, in most years, the majority of the hatchlings that emerge from the nests die due to predation, desiccation, and other factors. This is natural for a very long-lived animal. Imagine if 10,000 female tortoises across the Archipelago laid 20 successfully hatched eggs per year and they all survived — the Islands would quickly become overpopulated with tortoises. Then imagine how many eggs could be laid annually by the historical 100,000 or more female tortoises.

But when you are rebuilding a population from scratch, it’s better to ensure survival of more of the young. And which young do we want to eventually dominate the population? Those with the highest levels of Pinta and Floreana genes. Eventually the breeding program will end and all of the remaining captive tortoises will be released into the wilds of Pinta and Floreana. That decision, perhaps 10-20 or more years away, will be based on the health and size of the tortoise population on each island, the status of the genetic diversity of those populations, and various other factors.

Are you totally confused now? Don’t worry — we’ll keep it all straight. While we are sometimes mired in the minutiae of the work, we keep the long-term vision in mind: Pinta and Floreana Islands with hundreds, if not thousands, of saddleback tortoises wandering among the cactus, sleeping, feeding, mating, nesting, dispersing seeds, and living out their centuries-long lives; island ecosystems restored to closer to their pristine, pre-human condition with a myriad of species that depend, at least in part, on the tortoises. I dream of a day when the Galapagos Archipelago abounds with more than 100,000 tortoises, with continually increasing populations, until one day they equal tortoise numbers from before humans stepped foot in that wonderful world: a Galapagos always and forever with its full complement of iconic giants.

Dr. Linda Cayot is GC’s Science Advisor and has played an important role in Galapagos conservation efforts for more than 30 years.

The 2015 Expedition to Wolf: Keeping Tortoises Healthy

January 14, 2016

By Joe Flanagan, Chief Veterinarian at the Houston Zoo.

As a zoo veterinarian for over 30 years, I know that moving an animal to a new home is one of the most stressful things that can happen to it. Moves from zoo to zoo can bring out disease symptoms from otherwise unapparent bacteria, viruses, or parasites. Moves from the wild to captivity are even more likely to create problems — with a change in diet, a new social environment, and a need to learn to navigate new habitat, which includes people.To help animals in this transition, we treat them for both internal and external parasites — such as ticks — to reduce the load.

Ticks. Nasty, skin-crawling, blood-sucking, head-burying, disease-transmitting ticks. I hate them. Wild giant tortoises in Galapagos are frequently infested with dozens or even hundreds of ticks attached to their skin and even to their shells! I was fortunate to participate in the 2008 tortoise census on Wolf Volcano, and on that trip we encountered ticks on most of the hundreds of tortoises observed, as well as along tortoise trails. For the 2015 expedition, it was my job to get rid of as many of these nasty creatures as I could from the tortoises headed to the Tortoise Center on Santa Cruz. While ticks are “normal” on giant tortoises in Galapagos — part of the process of natural selection, as are the diseases they might carry — they are problematic for captive animals and the people who care for them. As for internal parasites, the primary ones affecting tortoises are worms. Like their external counterparts, there is a balance between the worm load and the tortoise, with wild tortoises regularly exposed to low levels. Some think the presence of intestinal parasites may help tortoise digestion. When a tortoise is stressed, however, a heavy population of worms can further weaken it. Although it is nearly impossible to eliminate all worms from the tortoises, by reducing the burden, the tortoises have a better chance of adapting to captivity.

During the planning phase of the 2015 Wolf Expedition, I worked closely with GC's Wacho Tapia to develop a treatment protocol for tortoises moving to the Tortoise Center on Santa Cruz and to ensure we had all the necessary supplies. After each tortoise was carefully delivered onto the deck of the Sierra Negra and freed from the net, we did a brief physical examination, took standard measurements, made sure each animal had a microchip for identification, collected a blood sample to verify genetics, and — in some animals — to look for tick-born disease. Before placing the tortoise into the ship’s hold, it was sprayed with a tortoise-safe insecticide and treated orally with a de-wormer, effective against the most-probable worms. Our goal was to improve the health of each tortoise, prevent “seeding” the corrals at the Tortoise Center with ticks and tortoise parasites, and, in consideration for the crew of the Sierra Negra, make sure the ship didn’t get infested with ticks!

As described in previous blogs in this series, locating tortoises on Wolf was slow until it rained on the third day. Rain brings tortoises “out of the bush.” The dispersed teams started to find tortoises, sometimes in very high numbers! Native Wolf tortoises are a large, dome-shaped species, which still occurs in high numbers due to the inaccessibility of their habitat precluding much harvest by whalers and other searfarers in centuries past. Although majestic and fascinating, these tortoises were not the objective of our mission so they were only counted and measured, then left to live their lives in one of the most unspoiled habitats in the world. But when a few of the teams started encountering tortoises “of interest” — animals previously identified by the Yale team as genetically significant or with the characteristic saddleback shape of those animals — we found ourselves scrambling, with tortoises arriving two or three at a time; sometimes with up to six giants wandering the deck before we could examine them. Near the end of the expedition, we worried we’d run out of space to house all the animals that were coming in! The ship’s hold was full. We started lining the gunnels with larger animals that were “misbehaving” in the ship’s hold — climbing over their brethren, and knocking over what we thought was safely-stowed gear. We ultimately collected 32 animals to form the breeding nucleus to resurrect two species of tortoises and to restore ecological balance to Floreana and Pinta Islands.

While my main “job” on this expedition concerned tortoise health and prophylactic treatment for potential disease organisms, I also joined the team that searched a patch of Wolf Volcano’s lower slopes for tortoises, going ashore each morning. Our zone was a patchwork of a’a lava, broken plates of pahoehoe lava, and fine soil, with vegetation ranging from completely barren to thick, impenetrable stands of woody vegetation. At this low elevation, we encountered few adult tortoises; most animals we found measured 6-18 inches in length. It is hard to believe that tortoises could survive in such a harsh environment, without anything green to eat and no source of water to drink. We humans left bits of skin and blood as we walked over the rough terrain and through thick and thorny vegetation. Each afternoon, we returned to the ship to receive and process tortoises. After the call-ins from the field teams, the helicopter made several trips to collect the tortoises. We’d watch its return against the backdrop of Wolf’s green slopes, trailing a net full of tortoises.

It’s hard to describe the feeling of being part of a conservation effort of this magnitude. For more than 20 years I’ve been lucky to visit these remote islands and work with their unique species, volunteering on numerous projects with myriad organizations. Over the years, I have witnessed many positive changes: invasive species have been eliminated on some islands; populations of some native and endemic species are recovering; and every year more of Galapagos is protected and restored to its primordial condition. But these projects are costly. Funding for this expedition came from the government of Ecuador, Galapagos Conservancy, and Yale University, as well as out of the pockets of the expedition's participants (many who donated their time). This high level of collaboration allowed funding from Galapagos Conservancy to be leveraged, resulting in a project many times larger than could be done by any one organization.

One of the greatest rewards of working in Galapagos is the great mix of people. The 2015 Wolf Expedition included participants from four continents — biologists, botanists, veterinarians, geneticists, technicians, park rangers, geologists, mariners, and pilots. Getting to know each other as we focused on our mission — talking, dining, traveling, and working together — a synergy occurred. New questions formed; some were captured for further consideration for future research projects; others were resolved or discounted. All resulted in friendships and collaborations that will last a lifetime. The conservation of one of the world’s greatest treasures is a unifying force. Galapagos is a magic place.

Joe Flanagan has been a veterinarian at the Houston Zoo for 33 years and has worked with the Galapagos National Park, the Charles Darwin Foundation, Island Conservation, and Galapagos Conservancy for more than 20 years in the restoration of biodiversity in the Galapagos.