Surfbirds News

Common scoters - plump, jet black diving ducks with long tails and bright yellow beaks on the male - have also experienced marked reductions in their UK range in the same period, with the remaining breeding population now restricted to isolated and remote freshwater lochs of northern Scotland.

Common Scoters, West Yorkshire © Sean Gray, from the Surfbirds galleries

The species has been surveyed nationally only once before in 1995, and the 2007 count was conducted to assess changes in common scoter numbers in the intervening years. Just 52 pairs were recorded in 2007, compared with 95 pairs in 1995 - a 45% drop in their numbers. The survey was a partnership between the RSPB, Scottish Natural Heritage (SNH) and the Wildfowl and Wetlands Trust. Fieldwork was conducted by four dedicated RSPB scoter surveyors working alongside RSPB regional and reserves staff, a team of WWT surveyors, and other volunteers.

Whilst thousands of Arctic and Scandinavian common scoters spend the winter off the British coast feeding in shallow waters, in summer the vast majority return to breeding grounds in northern Europe and Arctic Russia. The breeding population in Britain is the most westerly outpost for this species.

Although factors driving the reduction in the breeding population are still unclear and more research is needed to determine the precise causes, there are several possibilities.

The highest declines have been in the south and west of their British range; they have been lost completely from Loch Lomond and in Northern Ireland, so it is possible that changes to the climate could be pushing the birds further north.

Plantations and inappropriately sited forestry in the Flow Country of North Scotland have also led to changes in the water chemistry of some freshwater loch systems, causing invertebrate populations to shift. This could be restricting food availability and making it more difficult for them to thrive in their historical territories.

Common Scoter (female) © Josh Jones, from the Surfbirds galleries

Elsewhere predatory species such as pike have been introduced in some of the lochs where scoters used to breed and this could be responsible for higher chick mortality restricting their breeding success. However, some scientists believe that pike might actually help common scoters, predating smaller fish which compete with the ducks and their offspring for the invertebrates in the water systems.

Mark Eaton, research biologist with RSPB who led the survey, said: 'A decline of this nature highlights precisely the gravity of the situation facing common scoters in the UK right now. For this to have occurred in such a short time period is rare and of great concern. However, the news isn't all bad. We have a great track record of turning round the fortunes of species that have experienced such precipitous declines, such as the corncrake and the red kite. We really need to get out and conduct more research over the coming years to firmly establish the causal factors that have driven this reduction in the breeding population so we can stop it. We can then put together conservation measures and management schemes that will hopefully ensure that the common scoter can flourish in UK once more.'

Stuart Benn, senior conservation officer for RSPB in the Highland region, said: 'The remaining population is largely split between small freshwater peaty lochans in the Flow Country - many on RSPB's Forsinard reserve - and some of the larger hydro lochs in west Inverness, with the biggest historical declines on more nutrient and lime rich lochs in the South. The reasons for these differences are still unclear, so we need to establish why they choose to breed on such different water habitats, and why they aren't on all the apparently similar lochs. Once those questions are answered we can then work with the land managers such as the hydro companies who have already approached us for information on how they can ensure that these interesting diving ducks can continue to breed and flourish on our waters.'

Peter Cranswick, programme manager for threatened water birds at the Wildfowl and Wetlands Trust, said: 'The continuing decline in our rarest breeding duck is especially worrying. Common scoters became extinct as a breeding species in Northern Ireland in recent decades. These new results clearly demonstrate that urgent action is needed to avoid the same fate befalling the remaining birds in Britain.'