Storm petrels have been confirmed to be breeding at a nature reserve on an island in the Firth of Forth.

Nature Scot, the UK Centre for Ecology and Hydrology (UKCEH) and the Isle of May Bird Observatory have suspected there may be a colony there since 2019.

Their nocturnal habits make the species difficult to monitor but all three organisations made attempts to locate the birds, including playing back a recording of their calls over potential nest holes.

A bird has now finally been heard calling underground during daylight hours, when they could only be incubating or brooding a chick.

It is a very exciting find and amazing to be able to prove what has been suspected for a few years

UKCEH researcher Ella Benninghaus managed to confirm a bird was underground with a playback, after smelling the presence of their strong body odour.

She said: “Since storm petrels were first detected on the Isle of May in 2019, it has been an exciting but frustrating three years.

“We carried out some playback surveys with no success last year, but we were determined to try again this year.

“Sure enough, as I was lying on the ground I heard the storm petrel call back to me very quietly.

“It is a very exciting find and amazing to be able to prove what has been suspected for a few years.”

Mark Newell, also of UKCEH, added: “To confirm the presence of these mystical, magical birds 200 miles from the nearest known colony is one of the highlights of my many years on the isle.”

The vast majority of the storm petrel population can be found on remote islands during the summer, especially in the north and west of Scotland, but spend their lives out at sea.

David Steel, Isle of May reserve manager, said: “These special seabirds come ashore under the cover of darkness and nest underground in crevices, burrows, cairns or stone-walls.

“They will raise a single chick before eventually departing once again.

“During that time their nocturnal activities – singing away in total darkness – and unique smell contribute to make these birds so fascinating and mysterious.

“We’re delighted to have confirmation of storm petrel breeding after such a great team effort over the last three years by so many people.

“The Isle of May National Nature Reserve is hugely significant for its breeding seabird assemblage and this exciting news adds greatly to the importance of this special place.”