Kat Jones, from RSPB Scotland, has this fantastic new blog about monitoring seabirds on one of our most spectacular and least accessible reserves.

A pyramid of grey granite rimmed with 70,000 gannets

Ailsa Craig is one of RSPB Scotland's most spectacular and least accessible reserves. Each year a small team visits the island on three occasions to monitor the birds, plants and invertebrates and to look for evidence of rats.  

I've been fortunate enough to take part in the July visit and we head out on 'M.F.V Glorious', a wooden fishing boat, from Girvan under leaden skies. 

Ailsa Craig rises from the Firth of Clyde, a pyramid of grey granite rimmed with 70,000 gannets rising from the waters nine miles offshore. As we get closer, the lighthouse and decrepit pier come into view, built on the island’s only flat area, and the place that will be our camp-ground for the next two nights. 

As well as the usual monitoring activities, we are here to try and find out whether Manx shearwaters are nesting on Ailsa. Manx shearwaters, affectionately known as Manxies, nest in burrows on steep slopes high above the sea. 

The bird cliffs of Ailsa are only visible from the sea and so we do our bird counts by boat 

In the 19th century Ailsa was teeming with seabirds but when rats arrived on the island, birds could only successfully breed if they nested on inaccessible ledges. This meant that puffins, nesting on the grassy slopes, were wiped out and that Manx shearwaters, also burrow nesters, would be prevented from colonising the island. 

We are visiting with Bernie Zonfrillo, a veteran of 35 years working on Ailsa Craig. In 1991 he led the effort to exterminate the rats and still spends as much time as he can on the island monitoring and ringing birds. Thanks to the work of Bernie and his hardy group of volunteers the puffins returned to breed in 2002.

At night we heard the ghostly chatterings of the Manxies as they flew over our tent.  We know Manxies are around Ailsa but their nest sites are mainly so inaccessible, and they are active around burrows only at night, that it is extremely difficult to confirm that they are nesting on the island.

Last year a team camped near the summit of the rock, at 330m, to try and locate birds coming to ground. They didn’t see any land, nor have playback calls at burrows elicited responses. 

This time we are here with Ruedi Nager of Glasgow University and his thermal imaging camera. The idea is to use the camera to see Manxies coming into slopes on the island to get an idea of where more effort on the ground could be fruitful. It's a major challenge. All the slopes of Ailsa are extremely steep and dangerous.

One hardly existent path leads to the top. On the first night in a gale, the only place to set up the camera was sheltered behind the derelict brick building that manufactured coal gas for the lighthouse. We pointed the camera uphill and crowded into one of our tents, also pitched in the lee of the wall, to view the pictures on the laptop. 

Heading out to set up the thermal imaging equipment

The hulk of Ailsa Craig is a dull grey colour on the screen, with a jet black sky. Every now and again a hot white dot appears, a rabbit grazing on the slopes, or a gull wheeling above a small colony on the lower slopes. Every now and again we have tantalizing views of what could be Manxies on the screen.  And we hear them calling as they fly above us. 

We determine where it is we think the birds are and the next night we head up the hill carrying batteries, laptop and a small tent to pitch above our camp.

It is 1am when we head up the hill. The night is clear with a huge full moon. There is enough wind to keep the midges off, but it is warm, and we sit mesmerized by the view of lights moving about in the waters between Ailsa and the mainland.

A cluster of lights start at Girvan and fan out across the Clyde, trawlers headed out on the tide ripping up the soft sediments of the Firth of Clyde in search of langoustine. 

But the lights on the screen are quiet. There are gulls, but no Manxies. We don't hear them calling and we don’t see them. Disappointed, we pack up and return down the treacherous slope to the welcome of our beds, convinced in our hearts that the Manx shearwaters have come to breed on Ailsa at last, and determined to return next year to prove it.