A rare Madagascan wetland bird has been declared extinct in what scientists believe may herald the beginning of a global catastrophe only recorded five times in Earth’s history.

The dying out of the Alaotra grebe, found only in Madagascar and not seen for 25 years, has led biologists to claim we are on the verge of the ‘sixth great extinction’.

The previous five cataclysmic events during Earth’s prehistory, such as the extinction of dinosaurs 65 million years ago possibly caused by a meteorite hitting Earth, were naturally caused. This is the first time humans have been implicated in causing mass global extinction.

The Alaotra grebe has been declared extinct due to the introduction of carnivorous fish into its habitat and the use of fishing nets that caught and drowned the bird.

The disappearance of yet another type of bird has led scientists to believe that the rate at which species are vanishing from the planet could point to a period of mass global extinction.

Scientists now claim we could be on the verge of the next great extinction.

The RSPB’s international director Dr Tim Stowe said:

‘The confirmation of the extinction of yet another bird species is further evidence that we are not doing enough in the fight to protect the world’s wildlife. ‘Although there are some key successes, overall the trend is downward, bringing more species year on year to the brink of extinction and beyond.’

The inclusion of the Alaotra grebe on the International Union for Conservation of Nature (IUCN) Red List, which is the most comprehensive inventory of extinct species, comes as experts warned an eighth of bird species now faced extinction.

Bird species alone seem to be disappearing at the rate of one per decade.

The wetland bird was last seen in 1985 and its disappearance comes as experts warned an eighth of bird species now faced extinction.

The number of birds threatened with global extinction now stands at 1,240 species, according to the latest assessment.

The IUCN Red List’s update for birds, carried out by Birdlife International, said 25 species had been added to the list of those at risk.

Other wetland birds are under increasing pressure from the introduction of invasive species, as well as from drainage and pollution of their habitats, the conservationists warned.

Dr Stuart Butchart, Birdlife’s global species programme officer, said:

‘Wetlands are fragile environments, easily disturbed or polluted, but essential not only for birds and other biodiversity but also for millions of people around the world as a source of water and food.’

Along with the Azores bullfinch, the yellow-eared parrot from Colombia and the Chatham albatross have been downlisted from critically endangered to endangered.

Dr Butchart said:

‘These successes show what is possible, and they point the way forward to what needs to be done by the global community. 2010 is the International Year of Biodiversity; world leaders failed to stem the decline of biodiversity. We cannot fail again.’

EARTH’S FIVE GREAT EXTINCTIONS

• 65 million years ago: Cretaceous-Tertiary (K-T extinction). About 75% of species became extinct, possibly caused by a meteorite hitting the earth. Wiped out dinosaurs.
• 205 million years ago: Triassic-Jurassic extinction. Most non-dinosaurs were eliminated, leaving dinosaurs with little terrestrial competition.
• 440-450 million years ago: Ordovidician-Silurian. Two linked events that are considered together to have been the second worst extinction on the list.
• 360-375 million years ago: Late Devonian. A prologued series of extinctions that may have lasted 20 million years.
• 251 million years ago: Permian-Triassic. Known as ‘The Great Dying’ after about 96% of marine species and 70% of land species disappeared.

Source: Disappearance of rare wetland bird could herald the beginning of Earth’s ‘sixth great extinction’ - Mail Online

Date: 26 May 2010