Galapagos' new star tortoise a prolific dad - via Herp Digest

By Gonzalo Solano, nzherald.co.nz

Thursday August 16, 2012 

Lonesome George's inability to reproduce made him a global symbol of efforts to halt the disappearance of species. And while his kind died with him, that doesn't mean the famed giant tortoise leaves no heir apparent.

The Galapagos Islands have another centenarian who fills a shell pretty well. He's Diego, a prolific, bossy, macho reptile.

Unlike Lonesome George, who died on June 24, Diego symbolises not a dying breed but one resurrected.

Having sired hundreds of offspring, Diego has been central to bringing the Espanola Island type of tortoise back from near extinction, rangers at Galapagos National Park say.

Diego was plucked from Espanola by expeditioners sometime between 1900 and 1930 and wound up in the San Diego Zoo in California, said the head of the park's conservation programme, Washington Tapia.

When the US zoo returned him to the Galapagos in 1975, the only other known living members of his species were two males and 12 females.

Chelonoidis hoodensis - some consider it a species, some a subspecies - had been all but destroyed, mostly by domestic animals introduced by humans that ate their eggs.

So Diego and the others were placed in a corral at the park's breeding centre on Santa Cruz, the main island in the isolated archipelago whose unique flora and fauna helped inspire Charles Darwin's work on evolution.

Diego was so dominant and aggressive, bullying other males with bites and shoves, that he had to be moved eight years later to his own pen, with five of the females. The reptiles are not monogamous.

"Diego is very territorial, including with humans," said his keeper, Fausto Llerena.

"He once bit me, and two weeks ago he tried (again) to bite me. When you enter his pen, Diego comes near and his intentions aren't friendly."

A US-based herpetologist for the Galapagos Conservancy, Linda Cayot, says Diego is the most sexually active of the bunch because he's the biggest and the oldest of the males.

"In tortoises, the biggest dominates. It's not that the others aren't active. It's just that he's dominant," she says.

Tapia says it is impossible to know Diego's age, but he is well over 100. He estimates Diego is the father of 40 to 45 per cent of the 1781 tortoises born in the breeding programme and placed on Espanola island.

At least 14 species of giant tortoise originally inhabited the islands 1000 kilometres off Ecuador's Pacific coast and 10 survive, their features developing in sync with their environment, as Darwin observed.

Espanola, which encompasses 130 square kilometres, is arid, and in order to reach vegetation high off the ground, the tortoises there developed the longest legs and necks of any tortoise species in the archipelago.

Diego is nearly 90 centimetres long, weighs 80 kilograms and has a black saddleback shell.

Llerena says tourists take to him automatically, if from a safe distance.

"I think he's going to be the successor to Lonesome George, the new favourite."

A visit to Lonesome George became de rigueur for celebrities and common folk alike among the 180,000 people who annually visit the Galapagos. Among his last visitors were Richard Gere, Prince Charles of England and Brad Pitt, Angelina Jolie and family.

Before humans arrived in the Galapagos, the six islands were home to tens of thousands of giant tortoises. Numbers were down to about 3000 in 1974, but the recovery programme run by the national park and the Charles Darwin Foundation has succeeded in increasing the overall population to 20,000.

The offspring of Diego and his male rivals in the corrals of Santa Cruz have themselves been reproducing in the wild on Espanola Island since 1990.

"We can now say that the reproduction of this species is guaranteed," said Tapia.

Cayot was asked whether having so many children of the same few parents interbreeding on Espanola could hurt the breed's long-term prospects.

"It could be a problem," she said.

"But it is more important to save the species."