An internationally important seabird species is facing extinction on the St Kilda archipelago as a result of disruption to its food chain caused by climate change, a new study has found.

The black-legged kittiwake, a small coastal breeding bird, is on the verge of extinction and a dramatic drop in the number of fulmar was also recorded by the National Trust for Scotland’s (NTS) annual bird survey.

Across St Kilda the number of kittiwakes has fallen by 90 per cent since 2000 and surveyors found only one chick had been raised this season.

On the small island of Mingulay in the Outer Hebrides the kittiwake population has halved over the same period.

A decline in sand eels, which form an essential part of the kittiwake’s diet, has led to bird populations falling as they find it harder to feed.

It is believed the dearth of sand eels is due to rising sea temperatures off the Outer Hebrides caused by climate change.

Dr Richard Luxmoore, senior nature conservation adviser at NTS, said: “While the factors that have influenced the decline in our seabird populations are complex, there is evidence that changes in the food supply are affecting some colonies significantly.”

The number of occupied kittiwake nests on St Kilda has dropped from more than 500 in 1994 to just four this year. In 1994 the occupied nests fledged 394 chicks, but this year the figure was just one - experts usually expect nests to yield up to two chicks per season.

The northern fulmar has also seen its numbers halve across NTS sites, representing a pattern that can be seen throughout Scotland and the UK, with the lowest numbers on record at St Abb’s Head in the Borders, this year.

Dr Paul Walton, head of habitats and species at RSPB Scotland, said the data was “incredibly worrying” and called for designated protected feeding areas for seabirds.

“We have seen some really major declines in sea bird breeding success and numbers in Scottish colonies over recent years. Scotland has globally important populations of seabirds, we are of huge international significance and we have some of the best areas for breeding. In the northern isles we have seen over the past decade a really steep decline in breeding success and the knock on effect on the populations.

“RSPB Scotland are convinced that climate change is having a major ecological impact in the seas around Scotland that support internationally important populations of seabirds and they really depend the world governments coming together to do the right thing for climate change in terms of the marine environment in Scotland,” he added.

The black-legged kittiwake is a migratory gull, which breeds in large colonies on cliffs and is capable of using sheer, near vertical cliff faces for its nests.

Populations across the UK have more than halved since the mid-1980s, while in the population in Scotland has declined by almost two-thirds.

St Kilda is considered globally significant for its seabird colony, which numbers around 1,000,000, and is the most important breeding station in northwest Europe.

The archipelago lies more than 40 miles off the Outer Hebrides and is Scotland’s only natural world heritage site, it has not had a permanent population since the native islanders were evacuated in 1930.