CONCERN is growing over a 9% drop in hen harrier numbers in Scotland since 2010, the second successive decline according to the latest national survey of the birds.

Scotland is home to 80% of UK harriers, but only Orkney and Shetland have not seen a decline in numbers over the last six years. With the total Scottish population now estimated to be down to 460 breeding pairs – out of a total UK population now estimated at 545 breeding pairs – the RSPB warned this week that the species was now 'extremely vulnerable' to the effects of habitat degradation and wildlife crime.

The figures are the result of the fifth national hen harrier survey, carried out in 2016 by the RSPB, Scottish Natural Heritage and the Scottish Raptor Study Group, along with a range of other UK partners and covered the whole of the United Kingdom and the Isle of Man.

Citing independent research, the RSPB once again identified illegal killing as one of the main constraints on this species, along with a changing climate and the loss of heather moorland and other suitable nesting habitat to commercial afforestation and overgrazing.

The charity's head of species and land management, Duncan Orr-Ewing, said: “The hen harrier is an indicator of the health of our upland environment, and the fact that its population continues to decline is of major concern.

“The hen harrier is a high priority for our conservation work and urgent steps need to be taken to tackle illegal killing of this species and to improve their moorland breeding habitats.”

Wendy Mattingley, from the Scottish Raptor Study Group, said: “There is a very concerning trend of a long term decline in the number of breeding hen harriers in Scotland.

“For the population to begin to recover and expand over all suitable habitat, the intensively managed grouse moors of east and south Scotland must produce successful breeding hen harriers again. The hen harrier is a wonderful spectacular raptor and more action must be taken to ensure that its future is secure.”

Tim Baynes, director of the Scottish Moorland Group, said: “Harrier breeding fluctuates annually for many reasons – not all associated with wildlife crime. For example, 2016 was a poor year largely due to low vole numbers in Scotland with weather and predation shown to have played their part.

“Fifteen of our members, covering an area of 325,000 acres, will be working with the Heads Up for Harriers project again this year to better to understand the reasons for poor harrier breeding and to help rebuild the harrier population."

The study's lead author, Simon Wotton, said: “This survey required a monumental effort from a number of different funders, organisations and volunteers – without their help, dedication and expertise we wouldn’t be able to build up this accurate picture of these magnificent birds of prey.

“We hope these results will convince everyone in a position to help hen harriers to take positive steps to ensure their protection and rebuild the country’s population for people to enjoy for generations to come.”