Climate change hitting seabirds in Scotland and northern oceans hardest

Climate change is having a more severe effect on seabirds in Scotland and other parts of the northern hemisphere than elsewhere in the world, international research has shown.

Studies of 67 seabird species across the globe, including kittiwakes, puffins and shags, show a downward spiral in the number of chicks raised by fish-eating seabirds in the north.

The scientists have concluded that the rate of warming in northern oceans, which is faster than south of the equator, is having a dramatic impact on their survival.

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They also suggest that the impact of human activities such as overfishing and rising plastic pollution are exacerbating declines.

Seabird colonies in Scotland - on the Isle of May in the Firth of Forth and Foula in Shetland - have been analysed as part of a wider international study into the impacts of climate change on breeding success
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The research project analysed breeding success of colonies including those based on Scottish islands.

The fortunes of some of Scotland’s most iconic species - guillemots, razorbills, puffins, shags, black-legged kittiwakes and northern fulmar - was charted using data collected over more than 30 years on the Isle of May, in the Firth of Forth.

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Meanwhile, records going back almost 50 years revealed how populations of great skuas; Arctic skuas; arctic terns and black-legged kittiwake have been faring on Foula, in Shetland.

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Guillemots have been faring badly, raising fewer chicks as oceans warm. Picture: Gwyn Rees

The researchers found declines were apparent in several species at both sites, but these were most severe on Foula, in the far north.

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However, European shags in the Forth have been bucking the trend, which experts believe is down to their more diverse diet.

Most UK seabirds rely on small fish to feed their young, while several – such as kittiwakes and terns – are surface feeders.

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The academics fear the survival of these seabirds is particularly at risk if warming continues.

European shags on the Isle of May in the firth of Forth have been bucking declines seen in many other seabird species, thought to be down to their more diverse eating habits. Picture: Mark Newell
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Dr Francis Daunt, of the Scottish-based UK Centre for Ecology & Hydrology, was part of the international study team.

“Seabirds are sensitive to environmental disturbances and are therefore acting as canaries in the coalmine, alerting us to the deteriorating health of ocean ecosystems,” he said.

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“Their plight also indicates other organisms within the marine food web, including fish, marine mammals, large invertebrates and plankton, may also be struggling.

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“More research is needed to understand why some species are doing better or worse than others.

“Continued long-term monitoring of seabird populations and further global-scale assessments such as our study are essential to inform effective conservation action.”

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Study leader William Sydeman, from the Farallon Institute in the US state of California, said: “Seabirds can handle short-term declines in breeding success, but when breeding success becomes chronically poor, that’s not good,”

As climate warming alters ocean habitats, the locations of temperature zones in which various food sources thrive can shift away from seabird breeding sites.

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That’s when the birds suffer.

However, the team says long-term degradation of marine ecosystems is a more insidious problem and affects many other species as well as seabirds.

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Mr Sydeman added: “What’s also at stake is the health of fish populations such as salmon and cod, as well as marine mammals and large invertebrates, such as squid, that are eating the same small forage fish and plankton that seabirds eat.

“When seabirds aren’t doing well, this is a red flag that something bigger is happening below the ocean’s surface, which is concerning because we depend on healthy oceans for quality of life.”

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