There have been five mass extinctions in history. The question is, when can we expect the sixth? Or has it already begun? Marek Kohn reports

From INTELLIGENT LIFE magazine, January/February 2013

FOUR MONITOR SCREENS reveal the interior of the compound, a lattice of enclosures with high wire fencing folded inwards at the top and electrified. These units are surrounded by a windowless perimeter, maximising security and keeping access to a minimum. The volunteer in front of the screens flicks between them, dragging a mouse to move the cameras around the enclosures, which are scrubland habitats in miniature. She picks out their occupants, stocky felines whose purposeful demeanour is offset by the jaunty tufts they wear on their ears. These are Iberian lynxes, the most endangered cats in the world.

It’s feeding time. A partridge enters an enclosure and commences a tour of inspection; a lynx hurtles at it, legs stretching out almost flat, leaps and brings it down. These scenes are kept off the El Acebuche lynx centre’s live web stream, though they are critically important to the captive breeding project that is under way here in southern Spain. This lunchtime is a test for one cub, who has never seen a partridge before. She seizes and dispatches the bird in a flash: a promising tick for her survival skill-set.

Partridges are a once-a-fortnight treat at El Acebuche. Iberian lynxes, which are about half the size of Eurasian lynxes and comparable to American bobcats, subsist almost entirely on rabbits and cannot survive without them. Rabbits have been hard hit in the Iberian region by viral diseases, including myxomatosis, deliberately introduced into Europe in 1952. Iberian lynxes were themselves persecuted by Provincial Boards for the Extermination of Vermin in the 1950s. Extermination gave way to protection, but poaching continued, and the toll on the roads increased as traffic grew and lynxes were forced to roam wider in search of rabbits. By the mid-2000s there were fewer than 150 adult Iberian lynxes alive. The International Union for the Conservation of Nature (IUCN), which keeps the ledger of threatened species known as the Red List, classes the Iberian lynx as "critically endangered".

A 2010 census found that the numbers in the wild had increased to 250, and there are about 70 more in the captive breeding programme’s five centres. Some 30 are in El Acebuche: this one compound thus contains more or less a tenth of all the Iberian lynxes in existence, protecting them from pathogens and humans. The monitoring continues round the clock. Once an hour the observer on duty notes what each lynx is doing and records the details on a central screen, to build up individual behaviour profiles. These offer indications as to how the animals might fare if released to live free. One of the danger signs is being friendly to their keepers.

For Iberian lynxes, living free does not really mean living in the wild. They have to fend for themselves in terrain on which humans have one claim after another. Although the Doñana area that includes El Acebuche is designated a national park, it is not the kind of epic wilderness that the term suggests in the United States. It’s a reserve, hemmed and dissected, where some lines have been drawn in the sand. Although Iberian lynxes are exceptional in their scarcity, their conditions of existence are entirely typical on a planet that is being ever more densely colonised by its human population. The greater our dominance becomes, the more species will become as scarce as the Iberian lynx is today. Very few of them will benefit from the science, the technology, the volunteers, the political backing and the charisma that are combining to pull the lynx back from the brink. 

Already a quarter of the mammal species surveyed by the IUCN are classed as threatened. So are 41% of the amphibians, 13% of the birds, a third of coral species and a third of conifers. And that may not be the half of it. 

Five times in the history of life on Earth, mass extinctions have eliminated at least three-quarters of the species that were present before each episode began. The likely exterminators were volcanoes, noxious gases, climatic upheavals and the asteroid that did for the dinosaurs. Now a single species threatens to wipe out most of the others that surround it. We are faced with the realisation, as the ecologist Robert May puts it, that we "can now do things which are on the scale of being hit by an asteroid".