The common scoter is the only wildfowl species that is Red Listed as a breeding bird in the UK. There are only around 50 pairs left, with numbers having dropped by more than half over the last 25 years.
It is already extinct as a breeding species in Northern Ireland. A few pairs continue to nest in the West Highland glens of Scotland, with the core of the population being in the extraordinary blanket bogs of the Flow Country in the far north of Scotland.
Although there are several potential threats to the breeding scoters, there is no good scientific evidence to tell us which are actually causing the species’ decline.
Working with the RSPB and other partners, WWT researchers have been trying to gather the evidence we need, and identify the solutions to these problems.
We are examining:
- Whether predator numbers – especially of the introduced American mink – are too high for the breeding scoters to cope with. The spread of mink is a big concern, and the widespread planting of commercial conifer forests in the highlands might also be allowing predator numbers to build up.
- Whether climate change is changing the aquatic invertebrate food supply available to scoters. They probably time their breeding so that the peak food availability is when the ducklings are on the water. Warmer springs leads to earlier insect emergence and might mean that the birds get the timing wrong, miss the peak food, and the ducklings starve.
- Whether scoters compete with trout for food. Trout are widely introduced and managed in Scottish lochs. We think that where there are many small trout, they might outcompete the scoters, whereas a few large trout are less of a problem.
And the scoter is even more mysterious. Little is known about where they spend their time outside the breeding season.
Though common scoters aren’t that common as a breeding bird in the UK, tens of thousands appear in our coastal waters each winter.
WWT aerial surveys uncovered previously unknown populations and gatherings larger than previously thought in the Irish Sea.
We are not yet sure where these birds breed, nor where exactly ‘our’ birds – the ones that breed in the UK – spend their winter.
WWT chairs the UK Biodiversity Action Plan for the common scoter.