The winter population of Britain’s most common duck has almost halved in Scotland over the past 30 years, which experts believe is due to climate change creating milder conditions elsewhere.
The mallard, whose Scottish numbers are bolstered each winter by an influx of birds from north and eastern Europe, has recorded one of the greatest losses in recent years, with winter populations dropping by approximately 46 per cent in Scotland since 1982 and by 32 per cent since 1998 – according to the State of UK’s Birds 2011 report carried out by a coalition of wildlife organisations, including RSPB Scotland.
Other species found regularly in Scotland which have declined since 1998 include the pochard, whose population has dropped by 70 per cent, and the goldeneye, which has lost just over half of its population in the past 30 years.
The decline of the Greenland white-fronted goose is of particular concern as Scotland hosts a significantly proportion of the world population of this bird, on Islay, in Caithness and wetlands on the south-west. The population of this species has reduced by 40 per cent, while dunlin, a wading species which winters in mudflats, has lost just over a quarter of its population.
Experts believe that warmer climates in areas which were previously colder mean there is less need for birds to migrate to Scotland during the winter.
“Scotland has some of the most ornithologically important wetland sites in the UK, home to vital populations of waders and waterbirds, and valuable feeding ground for millions of migrating birds,” said Stuart Housden, RSPB Scotland director. “The fact that fewer of these winter visitors are reaching the UK may well reflect progressively milder winter conditions further north and east across Europe. This is a reminder that we still have much to learn about the long-term impacts of climate change and its consequences for wildlife across the globe.”
Susan Davies, SNH director of policy and advice, said: “Scotland has some world-class wetland sites and our bird populations are a vital indicator of the health of our environment. We ignore significant changes at our peril.”
The State of the UK’s Birds 2011 also revealed mixed fortunes for seabirds, many of which breed on Scotland’s coastlines. Arctic skua, herring gull and kittiwake have all suffered substantial declines since a national seabird-monitoring programme began in 1986.
Similarly, recent dedicated national surveys have revealed that the UK capercaillie population stands at 1,228, three quarters of which arein Strathspey.
However, the report does show that in Scotland, the downward trend is not universal with wintering numbers of wigeon, gadwall, teal and pink-footed geese all increasing over the same period.
David Stroud, senior ornithologist at Joint Nature Conservation Committee, said: “Forty years ago, governments agreed the Ramsar Convention on wetlands as an international treaty to stem the loss of the wetlands so critical to waterbirds and other wildlife.
“Many of the most important of the UK’s wetlands have since been designated as Ramsar Sites, but the report highlights some of the critically important sites.”