The rarer things become the harder they are to find. True, but this does not mean that there’s much respite for species approaching extinction. In fact, according to a new study published in the December issue of PLoS Biology, the human desire for rarity can send a species spiralling into an extinction vortex. This, the authors argue, is a consequence of the so-called Allee effect, a phenomenon where individuals in a low density population struggle to find each other to reproduce, with extinction the inevitable and rapid result. The price that some will pay for rare specimens means that humans can trigger an Allee effect and continue to exploit a resource until there’s nothing left to harvest.

It is because of this that I am the only Pinta giant tortoise left on earth. By the end of the 19th century, the whaling vessels were no longer stopping off on my island to collect tortoises – so few remained after nearly two centuries of exploitation that it just wasn’t worth their while. Nevertheless, a few dozen Pinta animals survived and might have staged a comeback were it not for the price of rarity. 

Believing the Pinta race as doomed, there was a race to seek out and bag the remaining individuals for the scientific record. Several expeditions in the 1890s and first decade of the 20th century spent several days on the island in the hope of finding just one specimen. Most found none. The last, that of the California Academy, weighed anchor off Pinta exactly 100 years ago. After days, they tracked down three large males on the misty upper slopes of the volcano. They skinned them and stowed them on board the expedition vessel. These three friends now sit on shelves in the basement of the Academy’s museum.

Since I hatched out on 16 March 1925, the California Academy expedition did not (as most then supposed) take the last Pinta tortoise. My mother, then small and young, survived I arrived in the first clutch she laid. I am the endpoint of Pinta’s extinction vortex.

So here’s the irony. Labelling a species as endangered, a measure designed to concentrate the conservation mind, may in some instances actually speed up its extinction. Education is needed but also tighter regulations to clamp down on those who refuse to be educated. Until such measures are firmly in place and enforceable, biologists may do well to think twice before reporting a species’ decline.