Climate change and warmer winter temperatures are one of main drivers contributing to declines in the population of Ireland’s wintering waterbirds at 97 wetland locations, according to a survey led by BirdWatch Ireland.
Fifteen species wintering in lakes, rivers and coastal estuaries are stable or increasing, but 20 are declining including six species that have decreased by more than 50 per cent since the mid-1990s, it finds.
The annual survey funded by the National Parks and Wildlife Service (NPWS) examined changes in 36 wintering waterbird species at the most closely-monitored wetland sites, spanning 15 counties.
Greatest declines were seen in "diving duck" species, namely goldeneye, pochard and scaup, which dropped by 65-90 per cent on average since the mid-1990s. Climate change and warming winter temperatures are undoubtedly one of the drivers of these declines, allowing these birds to spend the winter closer to their breeding grounds in northern Europe, it notes.
“At a more local level in Ireland, loss of habitat, changes to water quality, increased disturbance on lakes and in estuaries, and poorly situated developments all worsen the situation, meaning fewer and fewer of these birds return to us each year,” it concludes.
Wading birds of the plover family have undergone huge declines of over 50 per cent, it adds. Lapwing, traditionally referred to as the green plover and often considered Ireland’s national bird, declined by 64 per cent since the mid-1990s. The golden plover, which feeds on grasslands in the winter, has declined by a similar amount, as has the grey plover.
While Ireland’s breeding curlew population is teetering on extinction, with only around 100 pairs nesting here in recent summers, its wintering population is much larger as curlew from northern Europe migrate to Ireland from late summer to early spring. But these birds face similar threats as wintering curlew have declined by 43 per cent since the mid-1990s.
"We regularly do this sort of analysis at national level, providing a 'health check' to see how Ireland's wintering waterbirds are doing but now we're delving a bit deeper to see precisely where the problems are," said John Kennedy of BirdWatch Ireland, who led this research.
“Ireland’s waterbirds are indicators of the health of the wetland environment they use. These are sites that we depend on too - for drinking water, flood relief, agriculture, tourism, aquaculture and industry. As is always the case with this sort of research, it has answered some questions but poses many more, and we’ll be scrutinising these results in the months and years to come to decipher some patterns of change that might not be so immediately obvious,” he added.
On a more positive note, the black-tailed godwit has increased by 92 per cent since annual monitoring began in 1994, while the mute swan, little grebe and grey heron, which breed on Irish lakes and rivers. are stable or increasing in number. The little egret, has significant increased since it arrived into Ireland 20 years ago and is now widespread.
Species with a mixed report card include the light-bellied brent goose, which has increased overall but is now in decline. Numbers of Sanderling, the species on which the Pixar short movie ‘Piper’ was based, are 85 per cent higher than they were when monitoring began, but have decreased by 24 per cent in recent years.
“Recent declines of this magnitude are cause for concern and there is a risk that longer term increases for some species could be quickly undone in a few short years,” Mr Kennedy said.
NPWS waterbird ecologist Dr Seán Kelly said the success of the programme was down to the hundreds of citizen scientists who take part in the survey. “Data gathered under this survey allows us to further understand how and where conservation management and policies can be improved,” he added.