One in 10 avian species 'extinct by end of century'

By the end of the century one in 10 species of birds in the world will be extinct and a further 15 per cent will be on the brink, according to one of the largest studies of avian biodiversity.

It is estimated just over 1 per cent of bird species have become extinct in the past 500 years but habitat loss, disease and climate change will accelerate that tenfold in the next 100 years.

Stanford University in California found that the loss of birds will not only have an impact on other wildlife but could also increase the risk of disease hitting the human population.

The report cites the recent decline of three species of Indian vulture, caused by the widespread use of a veterinary drug by local cattle farmers. The decline led to an explosion in the population of feral dogs feeding off dead cows, leading to 30,000 cases of human rabies a year.

"Our projections indicate that, by 2100, up to 14 per cent of species may be extinct and one in four may be functionally extinct, that is critically endangered or extinct in the wild," said Cagan Sekercioglu, who led researchers in the study.

"Even though only 1.3 per cent of bird species have gone extinct since 1500, the global number of individual birds is estimated to have experienced a 20 to 25 per cent reduction during the same period," he said.

"Given the momentum of climate change, widespread habitat loss and increasing numbers of invasive species, avian declines and extinctions are predicted to continue unabated in the near future," he added.

The study involved analysis of all 9787 species of birds alive today, and of the 129 species that have gone extinct recently, to produce one of the most comprehensive databases ever compiled into the state of one class of animals.

Using a computer forecast, based on present rates of decline, the researchers found that just over one in four species is now prone to extinction and 6.5 per cent are "functionally extinct".

A quarter of fruit-eaters and omnivores are in danger, along with a third of herbivores, fish-eaters and scavengers.

In the worst-case scenario put forward in the study, published in the journal Proceedings of the National Academy of Sciences, the researchers predict that threatened bird species will increase by 1 per cent each decade.

"These assumptions are conservative, since it is estimated that every year natural habitats and dependent vertebrate populations decrease by an average of 1.1 per cent," the study said.

Gretchen Daily, a member of the research team, said it might be difficult to imagine how the loss of a particular species of bird can cause an outbreak of human disease. "Yet consider the case of the passenger pigeon. Its loss is thought to have made Lyme's disease the huge problem it is today.

"When passenger pigeons were abundant and they used to occur in unimaginably large flocks of hundreds of millions of birds, the acorns on which they specialised would have been too scarce to support the large populations of deer mice, the main reservoir of Lyme's disease, that thrive on them today," said Professor Daily.

- INDEPENDENT