Tuesday, June 26, 2012

Animal of the Week June 25 -- Bye George!

I couldn't let the passing of Lonesome George go unmarked—so here's one for the last Pinta giant tortoise (Chelonoidis nigra abingdoni), which died on June 24, age 100 or thereabouts. Since 1971 George has been recognised as the sole surviving member of a subspecies of Galapagos giant tortoise from the most northerly island of the archipelago, Pinta. The subspecies became known as the rarest animal in the world with just one known representative.

Originally there were perhaps as many as 15 subspecies of Galapagos giant tortoise, George's passing brings the total down to 10. When Darwin visited the islands in 1835 the differences between the shell shapes of the subspecies helped him to appreciate the nature of variation and adaptation: tortoises on islands with lots of moisture had large domed shells and grazed on grass and plants at ground level, those in more arid environments had saddle shaped shells that enabled them to browse shrubs and bushes.

The three familiar villains of overexploitation (by seafarers who used them as living larders), habitat destruction, and introduced species (particularly the goats) were responsible for bringing the population of over 250 000 Galapagos tortoises in 1600 down to as few as 3000 in the mid-1900s. The population has recovered to perhaps 20 000 now, but none of those are George's subspecies.

As the poster child of the plight of the Galapagos tortoises, George who appeared on Ecuadorean bank notes and postage stamps, was a focal point for conservationists; and his tourist pulling power has helped to raise a lot of money. Efforts to restore habitat, notably by the near eradication of feral goats from much of the Galapagos, have made the future much brighter for the other subspecies, if not for George and his closest kin. 

Attempts had been made to mate George with females of other closely related subspecies, but sadly he showed little interest -- he was a solitary fellow shunning most contact both human and testudine. But perhaps the story of the Pinta island tortoise doesn't end with George, there's stories of a Pinta tortoise in a German zoo, and some tortoises on nearby islands seem to be hybrids, raising the hope that even if a pure-bred Pinta tortoise doesn't still exist, their genetic diversity lives on.

Peter Hayward
Head Keeper
Animal of the Week
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