One more step in what scientists are increasingly referring to as the Sixth Great Extinction is announced today: the disappearance of yet another bird species. The vanishing of the Alaotra grebe of Madagascar is formally notified this morning by the global conservation partnership BirdLife International – and it marks a small but ominous step in the biological process which seems likely to dominate the 21st century.
Researchers now recognise five earlier cataclysmic events in the earth's prehistory when most species on the planet died out, the last being the Cretaceous-Tertiary extinction event of 65 million years ago, which may have been caused by a giant meteorite striking the earth, and which saw the disappearance of the dinosaurs.
But the rate at which species are now disappearing makes many biologists consider we are living in a sixth major extinction comparable in scale to the others – except that this one has been caused by humans. In essence, we are driving plants and animals over the abyss faster than new species can evolve.
Birds species alone now seem to be disappearing at the rate of about one per decade, and the extinction of the Alaotra grebe is announced in the BirdLife-produced update to the Red List of threatened bird species maintained by the International Union for the Conservation of Nature (IUCN).
A handsome bird not dissimilar to our own little grebe or dabchick, it inhabited a tiny area in the east of Madagascar, and declined after carnivorous fish were introduced into the freshwater lakes where it lived, and fishermen began using nylon gillnets which caught and drowned the birds. Its demise brings the total number of bird species thought to have become extinct since 1600 to 132.
Moreover, the new edition of the Red List shows that 1,240 species of birds (around an eighth of the 10,027 total) are themselves now in danger of disappearance – which is a rise of 21 from last year's assessment.
"The confirmation of the extinction of yet another bird species is further evidence that we losing the fight to protect the world's wildlife," said Dr Tim Stowe, international director of the Royal Society for the Protection of Birds. "Although there are some key successes, overall the trend is downward, bringing more species year on year to the brink of extinction and beyond."
Known only in Madagascar, and chiefly from Lake Alaotra, Tachybaptus rufolavatus was probably incapable of prolonged flight, so may never have occurred very far from the lake itself. None have been seen since 1999 and the most recent surveys in the region failed to find any birds.
"No hope now remains for this species," said Dr Leon Bennun, BirdLife's director of science, policy and information, announcing the change in its classification from critically endangered to extinct. "It is another example of how human actions can have unforeseen consequences. Invasive alien species have caused extinctions around the globe and remain one of the major threats to birds and other biodiversity."
drive from www.independent.co.uk