Global warming affecting Scottish birds?

EDINBURGH, Scotland (UPI) -- A survey of Scottish birds finds that global warming may be having an effect, with some once-common birds moving north.

The Breeding Bird Survey by the British Trust for Ornithology found that seven species are in marked decline in Scotland, The Scotsman reports. At the same time, other species are becoming more common as their ranges are also forced north into Scotland.

Generally, the declining species are those of higher elevations, the Scottish moors and uplands. Kestrels, lapwings, curlews, meadow pipits and oyster catchers have been placed on the amber warning list.

Numbers of swifts and hooded crows have dropped by more than one-third, the survey found. But because their declines have been observed over a relatively short time they have not yet been put on the warning list.