Country diary: Up close with these veterans of the ocean

‘At night-time they like to sit on and around the walls near to their burrows.’ Photograph: Camera Lucida Wildlife/Alamy

Two miles off the Llŷn peninsula in Wales lies Bardsey Island, an exposed, rocky landmass 1.5 miles long and just over 0.5 miles at its widest point. Bardsey mountain rises over almost half of the island, with a height of 167 metres and rare lichen species found at the top. It’s only reachable by boat and has just 12 properties, one being Bardsey Bird and Field Observatory – my home for the week.

I’m here for a university birders week, and on a clear, mild and slightly windy night – a relief given how strong the wind can get here – we head out into the darkness to look for a rarely seen and fascinating species.