Conservation Success Stories: Giant Tortoises Bounce Back!


As WC has mentioned before, in 2002, WC was lucky enough to visit the Galapagos Islands, a marvelous trip set up by two Fairbanksans. On the trip, WC saw his first giant tortoises, including the gravely endangered Española giant Galapagos tortoise. (These photos are scanned from slides taken in 2002. Both photo technology and WC’s skills have improved since.)

Galapagos Tortoise, Española Island, 2002

Galapagos Tortoise, Española Island, 2002

The long-lived, slow-breeding animals were jeopardized by human activities and, perhaps more critically, by the feral goats introduced in the islands. Whalers no long took dozens of live tortoises – meat that kept itself fresh – but the introduced goats had gone feral and had stripped the island of greenery far above the reach of the tortoises.

Starting in 1963 and ending in 1974, the last surviving Española Tortoises –12 females, 3 males – were taken into captivity. Feral goats were eradicated from Española Island. Galapagos National Park Service encouraged captive breeding among the survivors. In 1975, the Park Service began releasing the captive bred progeny into the wild. 

Lunchtime at the Giant Tortoise Breeding Facility

Lunchtime at the Giant Tortoise Breeding Facility

By 2007, a total of 1,482 tortoises had been reintroduced. As of a few years ago, about half are still alive. Including wild breeding, there are now nearly a thousand Española Tortoises. The historic populations were much higher, but the damage to the ecosystem by the goats is taking longer to recover. Happily, the tortoises themselves turn out to be remarkably effective agents for that process.

The tortoises are ecosystem engineers, like dam-building beavers or carnivores in Yellowstone National Park. By eating plants they defecate the seeds, slowly – giant tortoises don’t move very quickly – and thus the big reptiles direct the distribution and abundance of floral communities. So the added benefit of reintroduction has been the slow restoration of some of the ecological damage caused by the introduced and now eradicated feral goats.

By contrast, the efforts to encourage Lonesome George to breed were unsuccessful.

The Late Lonesome George, the Last Pinta Island Tortoise

The Late Lonesome George, the last Pinta Island Tortoise

Lonesome George was the last surviving Pinta Island Giant Tortoise, the rest of his species (some would say subspecies) having been extirpated by whalers. Efforts to breed Lonesome George were unsuccessful; the females of other Galapagos tortoise species couldn’t interest him. Other hybrids of Pinta Giant Tortoises have recently been found. Presumably, they were less fussy about mates than Lonesome George. A breeding program has been started, in an attempt to replicate the success with the Española species. But they will be hybrids; the pure strain is lost.

The moral, WC supposes, is that humandkind can be forgiven some, but not all of its ecological sins. As we annhilate even more species in this, the Anthropocene Era, it’s a lesson we need to keep in mind.

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