As morning breaks over a vast nature reserve in the heart of Buenos Aires, dozens of men and women clutching binoculars and cameras patiently scan the skies.

"Spoonbill" murmurs a man in one huddle, at which Mika Asikainen breaks off conversation and swings his eyes up to follow the bird's flight path overhead with a practised eye.

Mr Asikainen has come to Argentina from Finland for `.

BirdLife, the meeting's organiser, is looking for companies or individuals to act as species champions, putting up the cash that will fund the programme.

The group - which is the world's top authority on birds and their habitats - hopes to raise $40m (£22m, €28m) over the next five years. It estimates the average annual cost of saving a bird species is about $36,000 (£20,000, €25,000) and says it has signed up 24 champions to date and is finalising 18 more.

Current champions include the British broadcaster Sir David Attenborough, who is funding efforts to save the Araripe Manakin, a red-headed bird known only in one location in Brazil, and mining company Rio Tinto, which has championed New Zealand's flightless nocturnal Kakapo parrot, possibly the world's oldest living bird.

The 190 species classified as critically endangered by BirdLife include the Caerulean Paradise-flycatcher, native to Indonesia, whose population may now number as few as 19. BirdLife says 16 extinctions have been prevented through its conservation efforts in the last decade.

"It's not just a case of 'trees are pretty and birds are cute'," said author Margaret Atwood, the joint president of BirdLife's Rare Birds Club, who spent her childhood in a remote forest home to bears and moose in North-Western Quebec, and regularly returns to her family's log cabin there. "Birds are indicators, and what they're indicating is that our planet is in trouble," she told the FT.

Biodiversity matters: trees provide oxygen, the earth holds water and nutrients, jungle plants yield medicinal compounds and mangrove swamps are a defence against tsunamis. Destroying it means not just the loss of birds but ultimately that "you will die", Ms Atwood says.

Enlightened self interest is also a motive for some corporate sponsors. Andreas Pittl, head of nature marketing at Swarovski Optik, a maker of binoculars and telescopes and joint champion with Britain's Royal Society for the Protection of Birds of the Sociable Lapwing, says: "We need a healthy nature for people to buy our products."

The Sociable Lapwing breeds in Kazakhstan and Russia and winters in the Middle East, Eritrea, Sudan and India. "It lives and breeds in wide open spaces, so without high quality optics, it's difficult to see," Mr Pittl says.

The spoonbill Mr Asikainen spotted is relatively common, but experts warn that even familiar species are in decline, especially in Asia and Oceania, and birds worldwide are becoming extinct at a record rate.

"Everyone should understand that if birds aren't doing well, pretty soon we won't be doing well," said Mr Asikainen. "We depend on the same resources."

Threats to birds are chiefly man-made. The razing of forests or destruction of savannah for the production of biofuels or cash crops like soybeans, are prime culprits. Logging, fishing, mining, urbanisation, hunting and pollution are also perilous for the world's nearly 10,000 bird species and their habitats.

Sometimes the threats to birds come from predators like mice and rats, accidentally introduced by man. In Gough Island on Britain's Tristan da Cunha archipelago, giant mice terrorise the nests of the Tristan Albatross and eat the chicks alive.

Vultures in India, Nepal and Pakistan have been pushed to the brink of extinction by eating the carcasses of animals treated with the drug diclofenac. Meanwhile, climate change is a growing threat to many birds, as rising sea levels, storms and droughts change their habitats.

Jim Lawrence of BirdLife's Preventing Extinctions Programme, says critically endangered birds "have probably got no longer than10 years on the planet"

"If we don't get this underway before the Olympics come to London in 2012, it's too late," he concludes.