Rampant illegal logging in Indonesia and the demands of a rapidly expanding population and economy in Indonesia are killing many of Asia's most exotic and rare birds, conservationists said Thursday.

Birdlife Asia estimates that the sprawling southeast Asian archipelago is home to more than a third of Asia's endangered avian species, the highest concentration in the region.

"Bird species across the Asian region are in serious trouble," said Richard Grimmett, the head of Birdlife Asia. "Of the 332 species of birds that are endangered in Asia, Indonesia alone has some 117 species."

Speaking at a press briefing during the IUCN World Conservation Congress in Bangkok, Grimmett said the world could not afford to lose Indonesia's unique ecosystem.

Conservationists estimate that species like the sky-blue Caerulean Paradise-flycatcher and the Sangihe Shrike-thrush, are unique to the tropical islands of southeast Asia and cannot be found anywhere else on the planet.

Grimmett said that while few ordinary people would lament the passing of the Sangihe Shrike-thrush, the decline of even the smallest of bird species suggested the wider environment is in trouble.

"Like amphibians, birds are excellent indicators of wider biodiversity loss. When they're in danger, you can be sure that the environment as a whole is suffering," he said.

Grimmet blamed shrinking forests in Indonesia's Sumatra island for the rapid species decline.

"At the turn of the last century 90 per cent of Sumatra was covered in forest. Now it's down to 35 per cent, and if you look just at the lowland forests, that habitat has now almost completely disappered," Grimmett told Reuters.

"This is pretty dramatic loss of habitat over a relatively short period of time," he said.

A new report by Birdlife warns that one in eight of the region's 2,700 bird species are threatened, particularly in the Philippines, Vietnam, Cambodia, China and India.

The Important Bird Areas in Asia survey showed that only 43 per cent of the continent's almost 2,300 important bird sites were fully protected.

The outlook is equally grim for Thailand where vibrant wetlands and forests are coming under pressure from the demands of a booming economy.

Environmentalists warn that the Inner Gulf of Thailand, renowned for its rich wildlife, also faces severe degradation with the planned construction of a huge road bridge.

The kingdom has 62 Important Bird Areas (IBA) of which 22 are protected or partially protected.