Once a rarity, now eider duck is billed as best of the breeders
It's been a disastrous breeding season for many of our seabirds as cold, wet weather prevented eggs and chicks from staying warm.
But one species of sea-going duck has bucked the trend, achieving its best ever breeding season in Strangford Lough.
For years, the common eider duck was one of our relatively scarce seabirds and is still included on the UK’s Amber List which sets down species that are of European concern.
But in just 10 years, numbers on Strangford Lough have rocketed from about 20 pairs to 350 pairs this summer. Last summer, numbers were assessed by the National Trust as being around 250 pairs.
While other seabirds such as terns and black-headed gulls have suffered a catastrophic breeding season, the eider ducks have had their most successful season ever on the lough, according to National Trust warden Craig McCoy.
The reasons could be that they breed earlier in the year — when we enjoyed an unusual run of hot weather — or that they line their nests with the prized eider down that keeps eggs and chicks warm.
“They are a bird that over the last number of years hadn’t been doing so well and were one of our protected birds,” Craig said.
“But in very recent years they seem to be making a bit of a comeback. In Strangford Lough, numbers have been increasing over the last 10 years. We’d seen a very small number of them 10 years ago and they suddenly increased, up from about 20 pairs to over 350 this summer. They’ve really gone exponential over the last 10 years.”
And the reason behind the increase remains a mystery.
“Maybe they reached a critical number when they got together and have been successful ever since. Every year we see more and more,” Craig said.
Common eider remain scarce in England and Wales but have been doing well in Scotland, spilling south down the west coast into Northern Ireland.
“During the year they are out at sea ... and only come inshore to breed. In the summertime they come into Strangford Lough because of all the little islands there are to breed on,” Craig said.
Meanwhile, it’s been a bad summer for black-headed gulls which suffered from the cold and wet weather.
“The eggs didn’t hatch — and if they did, the chicks just couldn't warm up.
“The adult gulls survived, but the eggs and chicks just didn’t survive,” Craig said.
“If it is a decent summer next year that will be all right, but if we have a series of bad summers in a row the adult population won't be able to replace themselves.”
Common, arctic and sandwich terns all had a disastrous summer on Strangford Lough, with the number of chicks surviving to fledge thought to be down to single figures from thousands in previous years.
But there is evidence that some of the arctic terns gave up on their breeding attempts on Strangford Lough and moved to the Copeland Islands for another go, producing some 200 fledglings — the first hatched on the islands since the 1960s.