Return to Santiago: More than a decade after the eradication of the introduced goats, pigs and donkeys

July 23, 2018

By Wacho Tapia, Director of the Giant Tortoise Restoration Initiative

Santiago is one of the largest and most fascinating islands of the Galapagos Archipelago. In addition to an extensive arid zone, it has a very dense humid region, which at the lower altitudes is dominated by the native shrub glorybower (Clerodendrum molle). This shrub forms thickets that are impossible to pass through without an army of men skilled at wielding machetes — unless, of course, you are a giant tortoise and can bulldoze a tunnel straight through using your extraordinary strength.

native shrub glorybower (Clerodendrum molle) on Santiago

The native shrub glorybower (‘Clerodendrum molle’) makes for difficult passage.

Perhaps that’s why Santiago is little-studied. Although we launched the Giant Tortoise Restoration Initiative (GTRI) in 2014, and planned to begin work on Santiago in 2016, we didn’t make it until now. The trips were delayed for various reasons (including the extremely dense thickets of vegetation). In June, we finally completed our first trip focused exclusively on Santiago tortoises (Chelonoidis darwini).

Santiago tortoiseThis trip had a dual mission: 1) to open the access trail to Zone D – the closest giant tortoise nesting area to the coast, and 2) to evaluate the reproductive activity of Santiago giant tortoises there. We collected data that will help us, along with Galapagos National Park personnel, design a new strategy to accelerate the repopulation of Santiago with thousands of its giant tortoises. This tortoise species managed to survive for centuries, despite hundreds to thousands being removed by whalers and other sailors in centuries past as a source of fresh meat, followed by at least a century of negative impacts due to an immense population of introduced competitors (feral goats and donkeys) and predators (pigs that preyed on the tortoise nests).

The little literature available on Santiago tortoises indicates a small population of some 500 individuals, dominated by males. Although we did not do an island-wide census during our short and limited visit, we were disturbed to find that the few adult females we encountered were very old. More than ever, it is urgent that we develop integral research and management actions to restore this population toward its historical number, like the restoration efforts for other populations, such as the Española tortoise, which was even closer to extinction.

During this intense and interesting trip, several things caught my attention. One of the most striking was that almost all the Opuntia cactus we observed were sub-adults or juveniles of about 10-12 years old, which coincides with the eradication of the feral donkeys. That made me wonder: If the donkeys had not been eradicated, would we be looking at an eventual extinction of the cactus?

sub-adult opuntia cacti

Almost all the ‘Opuntia’ cacti on Santiago are sub-adults or juveniles.

Despite the daily physical effort of walking some 15 miles across rough terrain and under a scorching sun, every step walked and every drop of sweat spilled was worth it. In addition to giant tortoises, we experienced close encounters with Galapagos hawks, snakes, lava lizards, Galapagos flycatchers, mockingbirds, finches, and carpenter bees. We walked through young Opuntia cactus forests and saw many other unique Galapagos plants and animals. As the Galapagos Ranger Anthem says, “Never mind the fatigue or the pain to complete our mission.”

Santiago dense shrubberyWalking across Santiago took me back to my first contact with the island when I was 17. As a volunteer at the Charles Darwin Research Station, I was sent to Santiago for several months to assist with a study on sea turtle reproduction. Camped at Playa Espumilla on the northwest coast, we worked hard, especially at night when the turtles arrived at the beach to nest. After that experience, I didn’t return to Santiago for several years. Then, as a Galapagos National Park ranger, I made several trips as part of the program to eradicate the introduced ungulates (goats, pigs, and donkeys). It was then I discovered how vast the island is and how difficult to cross, despite the vegetation being severely impacted by feral goats at the time.

It has been well over a decade since the eradication of the introduced goats, pigs, and donkeys. Nothing is static in nature and the dynamic changes in the ecosystem that have occurred since then are impressive. Shrubs and trees are repopulating areas where they were absent for a long time. This dense vegetation made this recent visit a challenge. No one has used the “pica” (a local term for trail) that runs from the coast to Zone D since the late 1990s or early 2000s. The higher we climbed, the denser the vegetation. In addition to macheteing our way through thickets, we had to cross many relatively young a’a lava flows (young as in several hundred maybe a few thousand years), which increased the difficulty.

Water tanks on Santiago

Water tanks will collect water from the ‘garúa’ in coming months for the next trip.

In a few months we will return to Santiago to search for nests, collect eggs and transfer them to the Tortoise Center on Santa Cruz. We can go knowing that we will find an accessible “pica” and even more importantly, we can rely on water collected during this garúa (heavy mist) season in a tank we left for that purpose in Zone D. This will circumvent the need to transport all our drinking water from Santa Cruz and then carry it on our backs along with food and equipment. I look forward to the day when this island is covered with these giant reptiles that I have come to love and will continue to work to save.

Wacho TapiaWashington (Wacho) Tapia has served as the Galapagos-based Director of the Giant Tortoise Restoration Initiative since 2014. He coordinates and leads all GTRI fieldwork and plays a vital role in ecosystem conservation work in Galapagos. His work involves constant collaboration with the Galapagos National Park Directorate. 

All photos © Wacho Tapia / GTRI.

 

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  1. Amazing work

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