On a wing and a prayer

But the Scottish kestrel population has suffered a dramatic decline, according to the Royal Society for the Protection of Birds.

New figures collected for the Breeding Bird Survey have revealed that the number of the birds living north of the Border dropped by 54 per cent between 1995 and 2008 - then plummeted by a further 64 per cent in the following 12 months to leave just 7,500 breeding pairs in Scotland.

The population has declined at a far faster rate than in England, where kestrels numbers fell just 3 per cent in the 13 years to 2008 and 29 per cent from 2008 to 2009.

The RSPB now wants urgent government funding to pinpoint the reasons for the slump, which could include the effects of intensive farming and a decline in small mammals such as voles and field mice due to harsh winters.

Dr Arjun Amar, senior conservation scientist at RSPB Scotland, said: "We have already done research into some declining species, but kestrels, because they were previously fairly common, were not among them.

"But now we are facing a serious decline, which has taken us aback. We don't know why this has happened and as yet, haven't any indication of the patterns in the decline - whether it is happening more in farmland habitats or in the uplands."

He warned that kestrels were currently being spotted in only 42 of about 328 designated 1km "squares" used to chart populations of birds. The British Trust for Ornithology regards a species as too rare to generate a population trend once they are limited to just 30 squares.

"Once they are spotted in fewer than 30 squares, it statistically makes it very difficult for us to chart patterns and work out why this is happening - so this is a fairly urgent situation," said Amar, adding that the RSPB had contacted the Scottish Government and Scottish Natural Heritage (SNH) about the issue. "We urgently need funding to address this problem. We understand budgets are being tightened, but a lack of money to look into this problem is a major stumbling block."

Experts believe the fall in kestrel numbers could be caused by a variety of factors, including climate change-driven fluctuations in vole populations - which kestrels feed on - and illness caused by a build up of chemicals used in poisons eaten by the kestrels' prey. They also claim the populations could have been affected by changing land use in Scotland.

Kestrel populations dropped significantly in the 1960s and 1970s, due to the widespread use of a specific type of pesticide.Although they recovered following the withdrawal of these pesticides, the numbers started to decline again in the 1980s, which experts believe was a consequence of agricultural changes driven by the Common Agricultural Policy, which have adversely affected the kestrel's habitat and food availability.

Gordon Riddle, chairman of the South Clyde Raptor Group and an author of two books about kestrels, said the improvement in populations of other birds of prey such as ospreys, could also have affected kestrels by increasing competition for food - as well as the smaller kestrels becoming prey for some of the larger birds.

"It is very difficult to tell exactly why this has happened," he said. "In Scotland, we have carried out a lot of research into birds of prey over the years and many species have now recovered - but there is more pressure on kestrels now. We need more people doing work on the plight of the kestrel to pinpoint the true extent of the problem."

The birds generally have a short lifespan. Only around 20 per cent survive the first two years of their life to reach breeding age.

Andrew Stevenson, ornithological advisor for SNH, said: "The decline of the kestrel in Scotland is very worrying. We don't know yet why the decline in Scotland is more severe than the UK as a whole, but possible causes are changes to habitat and prey eating rodents killed with poison.

"It is certainly something we must investigate."