Species such as the curlew are disappearing from the uplands

Researchers carried out one of the largest surveys of bird populations ever conducted in the UK.

The study counted bird numbers in 13 upland areas of Britain, from Exmoor to the Outer Hebrides.

It found evidence of large declines in the populations of three wading birds - the lapwing, the curlew and the dunlin - north of the border.

Those species also saw their numbers fall across the UK.

Experts at RSPB Scotland said the findings of the Repeat Upland Bird Survey suggested that many species were leaving upland areas.

This study suggests that several species of conservation concern are in sharp decline Innes Sim RSPB Scotland

Further research will be conducted into the reasons for the decline.

Increasing numbers of alien tree types, climate change and predator numbers are some of the factors being considered.

RSPB Scotland spokesman Innes Sim said: "This important study suggests that several species of conservation concern are in sharp decline.

"The RSPB is now continuing with work to understand the underlying causes of these population changes so that appropriate conservation action can be taken to reverse declines."

He added: "It is interesting to note that species like golden plover and dunlin are doing well on the Isle of Lewis where the population of such birds is facing a serious threat from the planned 234-turbine wind farm on the peatlands."