Middleholm Island welcomes first Manx shearwater seabird count for 20 years

National Trust area ranger James Roden (left) on Middleholm Island with volunteer researchers from the Wildlife Trust of South and West Wales

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

The conservation charity has 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.

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.

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.

That’s why monitoring the species now is so important, says James Roden, National Trust area ranger for North Pembrokeshire: “We hope that by carrying out this census, we will see that the Manx shearwater population is stable or has increased, matching the trend we have seen on the neighbouring islands of Skomer and Skokholm. 

“Although Middleholm is much smaller than these adjacent islands, it still supports a significant proportion of the UK’s Manx shearwater population, as recognised with the Special Protection Area and Site of Special Scientific Interest designations.

“With many seabird colonies around the UK in real trouble, it is critical that these surveys are carried out, and we are happy to be working in partnership with WTSWW to achieve this.”

Pembrokeshire’s islands are home to more than 50% of the world’s Manx shearwater population
A close-up of a Manx shearwater
Pembrokeshire’s islands are home to more than 50% of the world’s Manx shearwater population

The surveying was conducted by James 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.

Manx shearwaters are well adapted for life at sea; they have long, narrow wings and small feet tucked far back on their bodies. 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.

The monitoring work involved playing Manx shearwater calls, which had been pre-recorded on an audio device, into a sample of burrows. If a bird responded to the call then the burrow was recorded as active as part of the survey.

With a large amount of data to collate, the results from the Middleholm Island Manx shearwater monitoring are expected to be released this winter.