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 Numbering just 15 some five decades ago, the tortoises, which can
live as long as two centuries, now number about 1,000 and can
sustain themselves, according to a study published in the scientific
journal PLOS ONE.
"We saved a species from the brink of extinction and now can step
back out of the process. The tortoises can care for themselves,"
said James Gibbs, a vertebrate conservation biology professor at the
State University of New York (SUNY) College of Environmental Science
and Forestry who led the study.
Located in the Pacific about 600 miles (1,000 km) west of Ecuador,
the Galapagos archipelago is home to an array of unusual creatures
that helped inspire Charles Darwin's theory of evolution by natural
selection following his 1835 visit.
Española giant Galapagos tortoises, their scientific name is
Chelonoidis hoodensis, measure 3 feet (1 meter) long with a
saddle-backed shell.
They live up to 150 or 200 years, eating grasses and leaves during
the wet season and cactus during the dry season on an arid, low,
rocky island measuring only 23 square miles (60 square km). Gibbs
said the population numbered perhaps 5,000 to 10,000 tortoises
before the arrival of people.
"The tortoises were hunted by buccaneers, whalers and other sea
goers throughout the 18th and 19th centuries," added Linda Cayot, a
herpetologist who is science advisor to the Galapagos Conservancy
group.
"They collected them live, stacked them in their holds, and had
fresh meat on their long voyages. Tortoises can live up to a year
without food or water, so a natural source of fresh meat," she said.
Gibbs said the tortoises had been given up as extinct by the time
the islands were protected as a national park in 1959.
In the 1960s, only 14 tortoises were found on Espanola, 12 females
and two males. They were all taken into captivity and a third male
was found in the San Diego Zoo. From those 15 tortoises, the
population was rebuilt through a breeding program in captivity
before they were reintroduced to the island.
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"Nobody knew how to breed tortoises in captivity and the best zoos
around the world had failed. The Galapagos National Park figured it
out and actually became exceedingly effective at it," Gibbs said.
The success story of the Espanola subspecies comes in sharp contrast
to the closely related tortoise found on the Galapagos island of
Pinta. In 2012, a male dubbed Lonesome George died in captivity as
conservationists tried in vain to find a way to breed him. He was
the last of his subspecies.
Even though the human threat was eliminated by protecting the
Espanola tortoise, the reptile still faced a formidable foe in goats
that inhabited the island for 90 years before being removed in the
1970s.
Introduced to the island by humans, the goats mowed down just about
everything in their path, including most of the cactuses the
tortoises thrive on.
Unlike the grassy place it once was, the island now is covered with
woody vegetation unsuited for tortoises. Gibbs said it could take
hundreds of years for cactuses to reach previous levels.
(Reporting by Will Dunham; Editing by Alan Crosby)
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