SCIENTISTS are to take to the mountains with MP3 players to find out why a species of bird is disappearing from its habitat.

The ring ouzel, otherwise known as the mountain blackbird, inhabits some the most remote countryside of Britain and Ireland.

But scientists are deeply alarmed at the speed the ring ouzel is disappearing from its habitat.

Andy Douse, of Scottish Natural Heritage (SNH), said: "This is a species in decline and the survey will give us a better understanding of this decline and should also give us more information about the pressure it may be facing."

It is the second time a national survey of the bird has been carried out.

The first survey was in 1999 and revealed the ring ouzel was disappearing from several upland areas where it was formerly widespread, including parts of Scotland, south Wales and large swathes of Ireland.

Ornithologists believe the bird has declined rapidly over the past century. In 1999, there were found to be fewer than 7500 pairs nesting in the UK. The decline was so marked that the ring ouzel was added to the red list of the Birds of Conservation Concern in 2002.

Innes Sim, an RSPB scientist who has been studying the bird for 14 years in Scotland, said: "The ring ouzel has a beautiful song and it sings on some wonderful stages, such as the mountains of Scotland, Wales and England."

He added: "I am deeply alarmed by its widespread and deepening disappearance: the hills would be lonelier without them."

For the new survey, scientists will play recordings of the bird's song at specific points. By observing the responses from male ring ouzels in the area they can establish the breeding status of any birds found.

The study will begin as the birds return to their upland nesting sites – from the end of this month – from their wintering grounds in the mountains and hills of North Africa and southern Spain. The project has been backed by Scottish Natural Heritage, the RSPB, Natural England, and the Countryside Council for Wales.

Although scientists cannot fully explain the bird's disappearance, recent research suggests a reduction in the survival of young and birds is to blame.

Factors may also include climate change; changes in livestock grazing which can affect the bird's nesting and feeding areas; hunting in Europe; and a reduction in the availability of juniper berries, the bird's main food source on the wintering grounds.