By Alex Kirby
BBC News Online environment correspondent
Another 2,000 species have been added to the annual Red List of the world's most endangered animals and plants.
Uhiuhi is a forest tree found only on the islands of Hawaii and O'ahu
The "official" catalogue produced by IUCN-The World Conservation Union now includes more than 12,000 entries.
This year, IUCN has highlighted the problems faced by many island habitats
which it claims face a bleak future.
It says many native animals and plants on the Seychelles and the Galapagos, for example, are being driven to extinction by invasive species.
Since AD 1500, IUCN says 762 plants and animals have vanished, with another 58 known only in cultivation or captivity.
Achim Steiner, the organisation's director-general, said: "While we are still only scratching the surface in assessing all known species, we are confident [the list of 12,259 species] is an indicator of what is happening to global biological diversity.
"Human activities may be the main threat to the world's species, but humans can also help them recover - the Chinese crested ibis, the Arabian oryx and the white rhino are just a few examples."
LIFEFORMS ON THE EDGE
See some of the other animals and plants with a Red Listing
The Red List threat categories are critically endangered (extremely high extinction risk in the wild); endangered (very high risk); vulnerable (high risk); near-threatened (close to qualifying as vulnerable); and least concern (this includes widespread and abundant species).
IUCN says island wildlife is being lost through the effects of invasive alien species, which have driven to extinction four plants from Ascension Island that were found nowhere else.
Other Atlantic islands, including Tristan da Cunha, St Helena and the Falkland Islands also face "unrelenting" pressure from invaders, grazing animals, and habitat loss.
The Red List says the future for Hawaii's plant life looks "grim" because of invasions, loss of pollinators that evolved with native plants, and human pressures.
The Mekong giant catfish has declined by more than 80% over the last 13 years
Of Hawaii's 125 endemic plants (species found nowhere else) added to the Red List this year, 85 are threatened.
There and on the islands of the Galapagos archipelago, snails are under threat, from other snails or from aliens like goats, pigs and fire ants.
Achim Steiner said: "Places such as the Galapagos, Hawaii and the Seychelles are famed for their beauty, which owes itself to the diversity of plants, animals and ecosystems.
"The Red List tells us that human activities are leading to a swathe of extinctions that could make these islands ecologically and aesthetically barren."
Cats and dogs
Continental species are also in trouble: the Mexican black howler monkey, the variegated spider monkey and the pied tamarin are all upgraded to higher risk categories.
In Asia the giant catfish of the Mekong basin, which can grow to three metres (10 feet), is now listed as critically endangered, because of overfishing, habitat loss and the obstruction of its migration routes by dam-building.
Its numbers have fallen by more than 80% since 1990. South Africa's riverine rabbit, also uplisted to critically endangered status, is now thought to number fewer than 250 breeding pairs.
The wild population of the St Helena boxwood currently numbers just 16 individuals
Apart from habitat loss, it faces trapping, and hunting by feral cats and dogs.
The oldest seed plants on Earth, cycads, which resemble palms, are among the most threatened plants.
Of 303 evaluated this year, 155 were listed as threatened. Seaweeds and lichens feature on the list for the first time, with Bennett's seaweed declared extinct: it was found only at two Australian sites, and has not been seen for a century.
IUCN is worried about two cetaceans, the Mediterranean sub-population of the short-beaked common dolphin, and the Rio Grande do Sul/Uruguay sub-population of the franciscana, a river dolphin.
Among the countries with the highest numbers of threatened birds and animals are Indonesia, India, Brazil, China and Peru. Plants are declining fast in Ecuador, Malaysia, Indonesia, Brazil and Sri Lanka.