Home of the hybrid tortoises with lineages from Pinta and Floreana Islands
By Wacho Tapia, Director of the Giant Tortoise Restoration Initiative (GTRI)
Wolf is the highest volcano in the Galapagos Archipelago, and one of the most challenging for field work due to its complex and capricious topography. My first experience with this beautiful and difficult volcano was in December 2008 when, as part of the technical team of the Galapagos National Park, I organized and led one of the largest scientific expeditions in Galapagos in recent years. Approximately 50 people participated in it, distributed in 10 separate camps, including park rangers, scientists, and logistical support staff. Those in logistical support — people who are normally invisible to the outside world — displayed tremendous physical capacity as they constantly transported food and water to the remote camps. In spite of the hostile terrain, huge and painful blisters on their feet, thirst, fatigue, and the inclement equatorial sun, they fulfilled their mission to ensure the safety and well-being of the rest of the team.
So before recounting tales of this most recent trip, I want to thank Novarino Castillo and his team, without whom we would never have collected blood samples from more than 1,600 tortoises in 2008. Genetic analyses of those samples at Yale University identified 17 hybrid individuals with genes of the recently extinct Pinta Island tortoise, and more than 80 individuals with genes from the Floreana Island tortoise — an island where tortoises have been extinct for 150 years. This provided us with the opportunity to recover these two lineages and repopulate their islands.
This past December, I returned to Wolf Volcano accompanied only by Dr. James Gibbs of SUNY-ESF and two Galapagos National Park rangers, Jeffreys Málaga and Carlos Vera. Camping at the coast this time, we had to cross a 4-km stretch of rough a’a lava each morning to start the climb to tortoises. Working in teams of two, we searched for tortoises, guided by GPS points of where hybrid individuals were encountered in 2008.
One delight of this trip was to witness the recovery of the vegetation resulting from Project Isabela and the successful eradication of goats from northern Isabela Island. In 2008, only a couple of years after the eradication, the area remained completely open and poorly vegetated. In 2014, we found a dense forest covering the slopes. In spite of the difficulty of making a path through the forest with our machetes, it was gratifying to see that ecological restoration is occurring — not only on Wolf Volcano, but throughout the entirety of Isabela Island.
Our first day searching for tortoises was frustrating. Despite having covered a large area, we only found a few individuals; perhaps because the vegetation was dry and there was little available food. On the second day, we climbed to the highlands in search of better habitat. After passing 200 m in elevation, the vegetation began to change from dry shrubs to trees, with green herbaceous plants growing in the understory beneath the canopy.
Around 11 AM, just above 400 m, a light rain began to fall. As we climbed on, the rain intensified and soon small streams flowed down the steep slope. Then something spectacular happened: we began to see traces of tortoises heading downslope. But we only saw footprints; no actual tortoises. We climbed another two hours to 800 m, where several hybrid Pinta and Floreana tortoises had been tagged in 2008. We still found none.
With persistent rain and no tortoises in sight, we began the long hike back down the mountain. This time we followed the fresh tortoise tracks, which helped us unravel the mystery. The tortoises had indeed gone to the highlands during the drought in search of food, but with the first sign of rain, they began their migration down the mountain to an area where rainwater temporarily accumulates.
At approximately 300 m, we found a gully where, even with little precipitation, the water collects in pools where tortoises can drink. Dozens of them were spread out all along the gully taking advantage of the water source, from 300 m down to 28 m, near their nesting zone. We were running out of daylight, so we quickly tagged and sampled those with semi- and full-saddleback shells — the typical form of Floreana and Pinta tortoises — and then hurried back to camp with the last vestiges of light.
Returning to the same area the next day, we were thrilled to discover many tortoises, several of them strongly saddlebacked, suggesting high percentages of genes from Pinta or Floreana tortoises. We collected more blood samples and must now wait for the genetic analysis to provide results.
After only a few days of very hard work with long hikes over rough lava, both Jeffreys’ and my boots were destroyed. Exhausted, we all experienced intense pain from blisters. But the trip had been successful. We could re-locate hybrid tortoises identified in 2008, and had found many previously unmarked tortoises with a shell-shape similar to the Pinta and Floreana lineage. We are now ready to plan the major expedition to Wolf Volcano later this year to expand the blood sampling work even further, and to collect as many of the Pinta and Floreana hybrids as possible to begin the breeding programs for the two islands.
Wolf Volcano is spectacular, especially for people like James, Jeffreys, Carlos and myself, who love nature. Each day back at camp, we were greeted with such wonders as flightless cormorants in a courtship dance, marine iguanas, and penguins — all sharing a patch of lava close to the sea. And every day ended with a spectacular sunset and with our cameras we were able to capture the sun in our hands.
All photos © W. Tapia and J. Gibbs