Belfast Telegraph

Strangford Lough wildlife feeling impact of changes in climate

Grey seals in Strangford Lough
Grey seals in Strangford Lough
Brent Geese
A Painted Lady butterfly
National Trust’s Hugh Thurgate
Mark Bain

By Mark Bain

Strangford Lough has seen a population explosion in grey seals and terns, new National Trust figures have revealed - although a changing climate means not all wildlife is in such good shape.

The 'stop-start' spring, with temperatures warming then plummeting in February and March before warming again, brought migrant species such as butterflies to the region.

But the changeable summer, with short, sharp rain storms, proved challenging for some and more deluges of rain, particularly in November, brought flooding in many parts.

There were a number of success stories around Strangford Lough with terns, grey seals, Brent geese and otters all showing an increase.

A protected species, the number of grey seal pups recorded annually has risen dramatically, from around six or seven greys in the early 1990s to more than 180 in 2019.

"We've been actively monitoring the seal population on the lough now since 1992 and grey seal numbers are up considerably in the last number of years," said Hugh Thurgate, lead ranger at Strangford Lough. "The peak count for adult grey seals visiting the lough during the breeding season this year was 282. This boom reflects the burgeoning UK population which is pushing the population down the North Channel and into the Irish Sea.

"There's also been an increase in the number of breeding areas available to the seals as more of the islands on the lough become uninhabited.

"The seals are looking for a safe and protected place to raise their young, somewhere that provides protection from the elements and is relatively free from disturbance and Strangford Lough offers them that.

"Unfortunately, the harvest or common seal is not enjoying the same kind of success on the Lough. Numbers of pups have flatlined to between 25-35 each year with the total population now alarmingly low at under one hundred."

Light-bellied Brent geese arrived back at Strangford Lough this autumn after a very successful breeding season in the east Canadian high Arctic.

Strangford Lough supports over 75% of the total population in the early autumn. Of the 20,950 counted on the official census date on October 11, 23.5% were recorded as juveniles.

But 2018 was catastrophic for the lough's terns. Heavy storms resulted in the swamping of the islands, causing a nest 'washout'.

A growing otter population with an appetite for tern eggs and chicks also contributed to a huge fall in healthy chick numbers.

The Trust's 2019 survey has shown much more promising results, with the number of young fledglings per pair up across all breeds.

In 2017, there were 155 young Sandwich tern fledglings, rising to 434 in 2019; common tern saw just 27 fledglings hatch in 2018, rising to 240 in 2019. In 2018, there were only three Arctic tern fledglings, but 198 this year.

"Much higher chick numbers are a direct result of a breeding season that was free from freakish storms and floods," said Hugh.

Closely linked to the Lough is the Ards Peninsula where the Trust has been working in partnership with the Ards Red Squirrel Group to restore the native red squirrel population.

Toby Edwards is the ranger leading the project.

"At Mount Stewart we have around 40-50 reds and across the whole Peninsula we estimate there are 120 reds now, which is close to the natural capacity for the area. This is great news and it shows what can be achieved when organisations work together to develop a plan for the protection of a species."

Warm spells of weather in the early half of the year saw migrant species of butterflies, moths and dragonflies from the south and east arrive in the UK.

Significant numbers of Painted Lady butterflies arrived en masse for the first time in a decade. In total, Painted Ladies made up more than half of all the butterflies and moths counted in Northern Ireland this year.

But 10 new species of moth were recorded here, many of which are migrant species.

Ben McCarthy, National Trust head of nature conservation and restoration ecology, said sightings of migrant insects and birds are becoming more common across the UK.

"This is a result of our changing climate. Although this can seem exciting, the obvious flip side is how these changes will start to affect some of our native species already under pressure from intensive land use, habitat fragmentation and climate change," he said.

"But if our wildlife doesn't have anywhere to move to as temperatures rise and the weather changes over the coming years we will inevitably see more and more species at risk of becoming extinct."

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