Warbling to a happy tune, the birds on the increase in Scotland

Published on Sunday 18 July 2010 14:58

THE numbers of chiffchaff, a distinctive woodland warbler, have increased in Scotland at almost seven times the rate of the UK as a whole.

The latest survey by the British Trust for Ornithology shows numbers of chiffchaff rose by 289 per cent in Scotland, compared to 43 per cent in the UK.

The small warbler, often seen flitting through woodland trees and shrubs with a distinctive tail-wagging movement, is recognisable for its song, from which it gets its name.

Another warbler, the blackcap, also increased more rapidly in Scotland between 1995 and 2008 than in the UK, according to the survey results. Its breeding population rose by 178 per cent in Scotland, and by 61 per cent in the UK as a whole.

Both birds migrate to southern Europe and Africa for the winter. It is thought those that breed in Scotland spend the winter in different areas to English breeders.

The different conditions they experience over winter may be linked to the variations in the rate of growth of the populations in Scotland compared to the rest of the UK, experts believe.

The results from the latest Breeding Bird Survey also reveal good news for the whitethroat, a warbler that winters south of the Sahara.

Whitethroats increased by 20 per cent in the UK overall between 1995 and 2008, but in Scotland numbers increased by 86 per cent.

However, some other birds have fared worse in Scotland than in the rest of the UK.

The kestrel, often seen hovering over motorway verges on the lookout for small rodents, declined by 54 per cent in Scotland between 1995 and 2008, and showed a further significant decline of 64 per cent between 2008 and 2009.

This was a far steeper decline than in the rest of the UK, where the amber-listed species dropped by 20 per cent between 1995 and 2008, and by 36 per cent between 2008 and 2009.

The reasons are not yet clear but a previous decline between the 1970s and 1990s has been linked to the impact on small mammal populations of agricultural intensification.

However, another raptor, the red kite, has seen its numbers rocket by 418 per cent in Scotland. And the breeding population of buzzards rose by 63 per cent.

Andrew Stevenson, ornithological adviser at Scottish Natural Heritage, said: "Whilst it is good to see some of our summer migrants doing well against the UK trend, the decline of kestrel is very worrying."

He added: "Quite why the decline in Scotland is more severe than the UK as a whole is as yet unknown and something we must investigate."

Other species that saw significant changes over the survey period include the yellow wagtail, which dropped by 52 per cent, the nightingale, which declined by 53 per cent, and the grey partridge, which suffered a 50 per cent drop.

Meanwhile, the greylag goose increased in number by 144 per cent in Scotland, and the Canada goose by 106 per cent.

The Breeding Bird Survey, a partnership between the British Trust for Ornithology, the Joint Nature Conservation Committee and the Royal Society for the Protection of Birds, monitors more than 60 species.