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Our conservation work on the Pembrokeshire coast

A group of Manx shearwater, grey and white sea birds, in flight over the sea
Manx shearwater in flight over the sea | © National Trust Images/Nick Upton

In June 2018 the Manx shearwaters on Middleholm Island (also known as Midland Isle) in Pembrokeshire were recorded for the first time in 20 years by the National Trust, as part of the Joint Nature Conservation Committee’s Seabirds Count census.

A significant colony

Together with neighbouring Skomer and Skokholm, Pembrokeshire’s islands are already recognised as the home of the world’s largest breeding colonies of the Manx shearwater, with approximately 50 per cent of the global population.

Partnership working

The National Trust worked in partnership with the Wildlife Trust of South and West Wales (WTSWW) to monitor the island’s Manx shearwater population which was last recorded in 1998 when the Seabird 2000 census took place. The monitoring work was made possible through funding support from Natural Resources Wales, The Seabird Group, The Wildlife Trust of South and West Wales and National Trust.

What did the data show?

The results indicated that the islands are now home to more than 50% of the world’s entire Manx shearwater population and that there are nearly half a million breeding pairs in total across the internationally important islands, with 89,000 on WTSWW’s Skokholm Island, 350,000 on WTSWW’s Skomer Island and 16,000 on Middleholm.

‘The 2018 census on Middleholm was the first time in 20 years that Manx shearwaters have been recorded on the tiny island, and it’s great to see that the population is much larger than we first thought.’

– James Roden, area ranger, North Pembrokeshire

Why was it necessary?

Monitoring the Manx shearwater colony is essential for assessing population health, understanding the conservation status of our internationally important seabirds and the effects of climate change on marine environments.

Two decades ago, there were 3,000 breeding pairs of Manx shearwater on the remote island, which is located off the Marloes Peninsula.

A challenging task

The surveying was conducted by area ranger James Roden and a team of five WTSWW volunteer researchers over one eight-hour day. The work was an incredibly sensitive operation as Middleholm Island isn’t usually open to the public, so there are no paths nor is there easy access to the island with the team reliant on a cliff-side scramble, a small boat and the weather.

On the island itself, the Manx shearwaters, as well as puffins, nest in burrows so the team had to watch their footing to ensure minimum disturbance to the fragile nests.

Easy prey

Manx shearwaters are well adapted for life at sea; they have long, narrow wings and small feet tucked far back on their bodies. However, life on land is far more awkward for the seabirds; they cannot walk easily and move clumsily, making them easy prey which is why they nest in burrows and only leave or return to their burrows at night to minimise the danger.

What did the monitoring work include?

The monitoring work involved playing the seabird’s social call, which had been pre-recorded on an audio device, into a sample of burrows across the three islands. If a bird responded to the call, the burrow was recorded as active as part of the survey.

Thank you

With your ongoing support, we're able to continue our vital conservation work. Thank you for helping to protect these special places.

The slipway, rocks looking out to sea, at Martin's Haven, Pembrokeshire


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