Inside the Galapagos Islands’ Giant Tortoise Rehab Effort
You’re sailing from the Spice Islands across the open ocean to the South American port of Guayaquil, your financial motives rooted somewhere along a broad spectrum of morality and lawfulness. Several months have passed, and food stores and morale are low. Fortunately, you know a spot that will save the day, a cluster of rocky islands jutting out of the east Pacific near the equator.
For centuries, the Galapagos Islands have been a convenience store for ocean-going journeys, the resident Giant Tortoises serving as the perfect solution to the constant challenge of acquiring fresh meat at sea. These enormous beasts could handle the rigors of shipboard life and could be harvested at any time. Ships throughout the 18th-20th centuries would stop at the Galapagos, herd dozens of tortoises onto the decks, and sail off, assured of a reliable protein source for the remainder of their journey. At one point, an American whaling vessel lost track of a captive tortoise, which ambled out of the hold two and a half years later in Nantucket. Befuddled onlookers promptly killed it and made a stew.
And so, slowly but surely, the Giant Tortoise population was decimated. By the mid-1900s, conservationists began to recognize the problem, just as the increasing rate of international tourism and commerce was introducing another mortal threat to the species.
This one came in the form of fire ants, a voracious invasive species with a taste for baby tortoise. “Within 20 minutes of hatching,” says naturalist Ernesto Vaca, “they swarm and make the baby tortoise disappear.” Other human-transported pests, like rats, dogs, and cats, have developed similar dietary proclivities. With the species now facing a genuine threat to its survival, the Centro de Crianza was founded on Isabela Island, and conservationists went into crisis mode, airlifting tortoises with helicopters and initiating a breeding program.
It took a while to develop effective breeding techniques, but today, the Centro boasts a near-perfect success rate from egg to teenage tortoise. The rescue program continues in full force, as the habitat surrounding Isabela Island’s many dome-shaped volcanoes have been deemed unsafe for tortoises because of the fire ant threat. Employees and volunteers venture into the dense forest to retrieve tortoise eggs, which are then placed into computer-controlled incubators back at the Centro. The sex of the fledglings is determined by egg incubation temperature – above 37.5 °C leads to females, below produces males – allowing the Centro to generate its ideal ratio of 60% females and 40% males. Just before hatching, the eggs are buried in sand to simulate natural conditions and ensure that baby tortoises can dig upward and outward, a capability that bodes well for future robustness. Until the young tortoises are two years old, they’re placed in cages to offer protection against rats. By five, they’re in open-air enclosures, having received microchips that will track their movements once released into the wild.
And that, after all, is the ultimate goal, to repopulate the Galapagos with one of its most iconic species. Already, several hundred adults have been reintroduced to Espanola, an island particularly hard-hit by wave of threats over the decades. But the long-term prognosis is murky, especially as the invasive species that predate upon tortoises continue to grow in numbers. One option is to bolster the invasive species eradication efforts; another is that the animals will merely live the first few years of their lives in controlled conditions. But for now, the stabilization of the Giant Tortoise population is a victory in itself, a promising example of how conservation efforts can bring an organism back from the brink. As human impact on the unique Galapagos ecosystems increases, the model of tortoise rehab may prove useful in protecting other species from extinction, allowing the islands to maintain their unique treasure trove of biodiversity.