UK divers buck Europe’s tumbling trend

The latest survey of black-throated and red-throated divers by the RSPB and Scottish Natural Heritage (SNH) has found the two species have increased in the UK by 16 and 34 per cent respectively in the last 12 years.

Both have declined in Europe overall and the black-throated diver was last week made a conservation priority by the UK government because of the declines elsewhere.

Man-made rafts, anchored in remote Scottish lochs, are thought to be helping the rarer black-throated diver breed more successfully but the good fortunes of the red-throated diver – the bird whose winter numbers altered the huge London Array wind farm – are a mystery, conservationists say.

Stuart Benn, Senior Conservation Officer for the RSPB, said: “To be increasing the numbers of these birds while they decline elsewhere is fantastic.

“Both species are highlights of the uplands – they look stunning and make some of the most fascinating sounds in nature. Divers are celebrated in American culture and should be similarly lauded and applauded here. They are brilliant birds.”

Black-throated divers rose from 187 pairs in 1994 to 217 pairs in 2006 but have declined by more than 50 per cent across Europe since 1970. In the Highlands – their stronghold – they were declining because fluctuating loch waters were flooding some nests while eggs on others were being lost to collectors and predators.

The new study shows the greatest increase in the Outer Hebrides but in the Highlands, numbers of this yodelling bird have also risen. A total of 58 rafts have been installed in remote lochs in the region.

Planted with turf and heather, the rafts look like natural islands within two years. “We installed them because of the flooding of lochs with a lot of incoming water or with hydroelectric dams,” Stuart Benn said. “The rafts also protect the birds from land predators and birds now using the rafts are producing twice as many chicks as those nesting on land.

“We can’t say hand on heart that the overall increase is due to the rafts because we haven’t ringed the chicks but there is no doubt that the rafts have turned out to be very, very good at what they do.”

Red-throated diver numbers have jumped from 935 to 1,255 breeding pairs in 12 years. However, the Shetland population is still much lower than the 700 pairs found in 1983. That study surveyed Shetland only and the new results showed only 407 pairs nesting on the Isles.

The red-throated diver is steeped in mythology and is known as the rain goose in its strongholds of Orkney and Shetland. In the 19th century, it was regarded as a foreteller of storms in many parts of the world.

Dr Mark Eaton, an RSPB scientist, said: “We feared the numbers of red-throated divers might drop because the warming of the North Sea seems to be reducing stocks of the fish they feed on. The black-throated diver could also be at risk in the future, despite the recent increases. If climate change causes loch temperatures to rise, the small fish the birds feed on could grow too large to eat.

“Divers are up there with eagles and other iconic birds and are one of the things people go to Scotland to see. They are birds of mountains and lochs so if you are watching them in Britain, there’s a good chance you’re in picture postcard countryside as well. We should be doing all we can to tackle climate change and limit the damage to these birds’ habitats.”

Dr Sue Haysom, an ornithologist with SNH, said: “SNH is greatly encouraged by the signals coming from this research. These are key species of Scotland's wild loch habitats and any increase in their numbers is a welcome contribution to the health of Scotland's natural heritage.”