By Richard Black
Environment Correspondent, BBC News website
Researchers have compiled a global map of sites where animals and plants face imminent extinction.
The list, drawn up by a coalition of conservation groups, covers almost 800 species which they say will disappear soon unless urgent measures are taken.
Most of the 800 are now found only in one location, mainly in the tropics.
Writing in Proceedings of the National Academy of Sciences, the researchers said protecting some of these sites would cost under $1,000 per year.
"This is a whole suite of species threatened with extinction," said Stuart Butchart, global species programme co-ordinator with BirdLife International, one of the groups behind the report.
"Most of them are living on single sites and are therefore highly vulnerable to human impacts," he told the BBC News website.
"Safeguarding this suite of sites is not the only thing we need to do; but if we don't protect them, these are guaranteed extinctions."
Aiming for zero
The list of organisations behind the study reads like a Who's Who of the conservation world, with the Zoological Society of London, Conservation International, and the American Bird Conservancy among 13 groups involved.
They come together under the umbrella of a relatively new organisation, the Alliance for Zero Extinction (AZE), whose aim is exactly what the name implies.
From their databases they have drawn up a list of 595 sites which contain at least one species classified as "endangered" or "critically endangered" according to criteria laid down in the Red List of threatened organisms.
Each is either the only place where that creature resides, or contains at least 95% of the known population.
Some of the sites contain more than one endangered species.
Because not every organism on the planet has been studied or even identified, the 794 species include only birds, mammals, amphibians, conifers, and some groups of reptiles.
The majority of the key sites are in tropical regions of the world, and most in developing countries.
On average they are in places where the human population density is high; a minority are fully protected.
Price of failure
For John Fa, director of conservation science at Durrell Wildlife, working with communities is the key to conservation strategies in these regions.
"Our strategy is not just to focus on the animals but also to work alongside local communities so we do something for their livelihoods," he told the BBC News website.
Projects run by Durrell Wildlife include captive breeding of species like the pygmy hog of Assam and the ploughshare tortoise in Madagascar.
Many threatened species like the Maui parrotbill live on islands
Both animals are now being re-introduced into the wild.
"In Madagascar, the community benefits," said John Fa, "because we have been able to attract donor money to support the establishment of schools, building of wells, and starting initiatives like home gardens; so people see there are benefits from conserving wildlife."
The AZE team has calculated the cost of conserving each of the 595 key sites; they conclude that the annual price would vary hugely, from $470 up to $3,500,000.
The higher end of the scale might appear prohibitively expensive, but Stuart Butchart is optimistic that at least some can be properly protected.
"The message that these are species restricted to single sites is quite a powerful argument for the public," he said.
"It's impossible to know or predict how long these species might have; but certainly within the next few decades, if these sites aren't protected, they will be gone."