New warbler bird species discovered in Vietnam

Scientists have discovered a new species of warbler in the forests of Vietnam and Laos.

The small green and yellow bird was first sighted in 1994, but at the time was thought to be a different species surviving 1000km from its usual home.

Now, according to a report by BBC News, studies of the bird's morphology, DNA and vocalizations have confirmed it to be a unique species, and scientists have named it the Limestone leaf warbler.
 
"The bird was first seen at one place in Vietnam in July 1994 and again at the same place in April the following year, and in one area in central Laos in May 1995," said taxonomist Professor Per Alstrom of the Swedish Species Information Centre, a part of the Swedish University of Agricultural Sciences in Uppsala.

"Initially, the bird was identified as a Sulphur-breasted warbler, in itself an interesting finding, since it was apparently breeding more than 1000km south of its previously known breeding areas in China," he said.

"Later, it was realised that its songs differed markedly from the songs of the Sulphur-breasted warbler, and further studies were undertaken," he added.

These studies by Prof Alstrom and colleagues, who included scientists from the Wildlife Conservation Society's Lao Program and Birdlife International in Indochina, confirmed the bird's unique identity.

The plumage of the Limestone leaf warbler is almost identical to that of the Sulphur-breasted warbler, though the new species appears to have a colder yellow chest and more grey topside and stripped crown.

But, the new species is smaller, with shorter wings, rounder wing tips and a proportionately larger bill.

"Its vocalizations, both song and contact call, are markedly different from those of the Sulphur-breasted warbler," said Professor Alstrom.

DNA analyses also suggest that it is more closely related to the Yellow-vented warbler from eastern Himalayas, northern Laos and adjacent part of China, which is quite different in plumage.

"Leaf warblers and many other warblers are renowned for being very similar-looking, while having distinct vocalisations, so it is very likely that other new species of warblers will be discovered," said Professor Alstrom.

Despite being unknown to science as a new species until now, the Limestone leaf warbler is quite numerous.

Professor Alstrom's team believes that the bird inhabits limestone karst habitats in Vietnam and Laos, and may also breed in several locations in southern China.