Matt Walker BBC Nature 7 Jun 11;
One of the heaviest flying birds in the world is in danger of going extinct, conservationists are warning.
Great Indian bustards stand a metre tall and weigh up to 15kg, yet as few as 250 may now survive.
That is according to the latest edition of the IUCN Red List for Birds, which reports that the total number of threatened birds species has risen to 1253.
That means 13% of all surviving bird species are now threatened.
The 2011 edition of the International Union for the Conservation of Nature Red List for Birds records the changing prospects for the world's bird species.
"In the space of a year another 13 bird species have moved into the threatened categories," said Jean-Christophe Vie, deputy director of the IUCN Global Species Programme.
In all, 189 species are now considered to be Critically Endangered, including the Great Indian bustard.
The bustard was once widespread across the grasslands of India and Pakistan. But now its range is restricted to small isolated fragments, with its last stronghold in Rajasthan.
Other species on the brink of extinction include the Bahama oriole (Icterus northropi), also newly listed as Critically Endangered.
Recent surveys suggest that perhaps just 180 individuals of this black and yellow Caribbean bird may survive.
The orioles live in mature woodland, and nest in coconut palms, according to BirdLife International, an alliance of conservation groups that leads on putting together the Red List for birds.
The oriole is also threatened by the recent arrival of the Shiny cowbird (Molothrus bonariensis), a brood parasite that lays its eggs in other species' nests.
Some species are faring better than in past years.
For example, the Campbell Island teal (Anas nesiotis) has benefited from a massive programme to eradicate rats, plus captive-breeding of remaining individuals.
The species has now returned to New Zealand's Campbell Island, resulting in a reclassification of its threat status to Endangered.
Around the world, the greatest concentrations of threatened bird species occur in the forested tropics.
A disproportionately high number of threatened species, almost half, occur on islands, particularly oceanic islands far from land.
For seabirds, the greatest concentrations of threatened species are found in the southern oceans, notably around New Zealand.
In 2010, BirdLife confirmed the extinction of Alaotra grebe (Tachybaptus rufolavatus).
Over the last 500 years, invasive alien species have been partly or wholly responsible for the extinction of at least 65 bird species, according to BirdLife International.
