A bird-eating frog, a technicolour gecko with orange eyes and a bird that flies only when it is frightened are among dozens of new species discovered in an ecologically fragile part of Asia.

Researchers in the Greater Mekong area of South-East Asia also found a tiger-striped pitviper, a new wild banana and, even rarer, two new types of mammal, a report for the wildlife charity WWF says.

However, conservationists fear that the discoveries, many of which are unique to small areas of jungle, river or mountains, are under threat from destructive development and climate change.

The most colourful of the finds is the Cat Ba leopard gecko, described as “a creature that appears to be from another world”. Large, dark orange eyes are set in a head decorated with a marble pattern, while its body is covered with leopard-like swirls, which scientists believe may provide camouflage in the forest. The rare gecko, confined to one small island in northern Vietnam, is already thought to be endangered.

A fanged frog, confined to three remote forest sites in Thailand, waits for its prey in streams, pouncing on insects and other frogs. But researchers have found feathers in the frog’s faeces, proving that it eats small birds as well. Male frogs also use their fangs to fight other males, sometimes tearing off limbs.

More timid is the Nonggang babbler, a bird found only in one nature reserve on the border of Vietnam and China. The babbler spends most of its time on the ground, foraging for insects between rocks. Scientists rarely saw the bird in trees, and believe that it takes to the air only when it is frightened by predators, a form of behaviour unknown in other babblers.

The discoveries are among 163 new species found last year in the countries around the Mekong river — Cambodia, Laos, Burma, Thailand, Vietnam and the Yunnan province of China. More than 1,000 new species have been discovered in the area over the past decade, as scientists have begun to explore its remote and unique ecosystems.

Heather Sohl, a species officer at WWF UK, said that there were two reasons why so many finds had been made recently. “One is that there have been political difficulties in the area, which is now beginning to open up. The other is that there are a lot of isolated habits that lead to the evolution of species not seen elsewhere.”

But she said that the uniqueness of these areas left them particularly vulnerable to threats from development and from the ecosystem disruptions likely to result from climate change. “It is very worrying that no sooner do we find a new species like the fanged frog and the leopard gecko, than we have to sound the alarm over their prospects for survival,” Miss Sohl said.

“Rare, endangered and endemic species like these will be especially vulnerable to climate change, which has the potential to reduce their already restricted habitats.”

Among the 100 plants discovered in 2008 were six new orchids and a wild banana with striking red flowers. Researchers also found 28 types of fish, 18 reptiles, 14 amphibians, one bird and two mammals — a tube-nosed bat and a white-toothed shrew.

The finds join the Indochinese tiger, the Javan rhino, the Irrawaddy river dolphin and the Mekong giant catfish on the list of unique species in the region. The area is so rich in wildlife that scientists have stumbled across new species by accident, including last year’s discovery of the tiger-striped pitviper. Lee Grismer, of La Sierra University, California, said: “We were engrossed in trying to catch a new species of gecko when my son pointed out that my hand was on a rock mere inches away from the head of a pitviper. We caught the snake and gecko, and they both proved to be new species.”

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