This autumn, conservationists will be setting off on a voyage to the Calf of Man, a tiny island off the south western tip of the Isle of Man to help some very special seabirds – the Manx Shearwaters.
Manx National Heritage (MNH), which owns the Calf and runs the bird observatory there, is being joined by a partnership of conservation organisations in a project to ensure the sustainable recovery of the Calf’s Manx Shearwater population.
The Manx Shearwater
Manx National Heritage, is working with the Manx Wildlife Trust, Manx BirdLife, and the Department of Environment, Food and Agriculture, with substantial technical and practical assistance from the Food and Environment Research Agency (Fera), financial support in the form of a generous grant from the RSPB and funds from the MNH Trustees, to re-establish the Calf as a safe breeding location for Manx Shearwaters. The Isle of Man has a responsibility to help conserve the Manx Shearwater, a species of European Conservation Concern and registered on the Amber List of UK Birds of Conservation Concern, due to its declining range and localized breeding patterns. As much as 80 per cent of the world breeding population, just under 300,000, occurs in the British Isles, making the species vulnerable to adverse changes in breeding habitat, food supply or other factors. The species also has a special historical significance for the Isle of Man, as the Calf’s colony of Manx Shearwaters were first described in an account of the “Mank Puffin” in “The Ornithology of Francis Willughby” published in 1678.
It is believed that Manx Shearwaters once occupied the Calf of Man in their thousands. The Manx Shearwater young were harvested annually in large numbers for their flesh and oil which must have taken a toll on the colony. However, the population declined catastrophically following the arrival of brown rats (‘longtails’) on the Calf, believed to have been the result of a shipwreck in 1781. By the beginning of the nineteenth century, the Calf colony of Manx Shearwaters was all but wiped out as a result of rat predation of the chicks and possibly the eggs and even adult birds. Small numbers of Manx Shearwaters have managed to re-establish themselves on the Calf in recent years but a persistent residual population of rats remains a threat to the species, despite on-going rodent control since 1979. Following the unusually cold winter last year, however, the rat population appears to be at a low ebb, providing a rare opportunity to eradicate completely this non-native, highly invasive predatory mammal from the Calf and give our seabirds a better chance of breeding successfully.
Kate Hawkins of Manx National Heritage said:
‘This is a really exciting project and a chance to regain the Calf’s standing as the symbolic ‘home’ of the Manx Shearwater. If we can achieve a longtail-free Calf, the prospects for other ground nesting birds are also much improved. I hope that the public will support this project and help us to save these wonderful birds.’
In addition to conserving the Manx Shearwater, the project is anticipated to provide a more favourable environment for crevice- and burrow-nesting birds such as Storm Petrels and Puffins, potentially leading to colonization and breeding. Both species are on the Amber List of UK Birds of Conservation Concern and the Puffin is of concern in a European context.
Other colonies of nesting seabirds are also anticipated to benefit including Shags, Lesser Black-backed gulls and Fulmars. All three species are Amber Listed, with Fulmars suffering a worrying 38% decline in UK numbers between 1999 and 2009.
As one of the 18 accredited bird observatories in the British Isles and an officially recognised bird observatory for 50 years, the Calf of Man has built up a large and scientifically valuable set of data about the birds which frequent or pass through the Isle of Man or occur in its coastal waters.
The project on the Calf of Man is supported by experts from the RSPB, who recently visited the island. In their follow-up report, the RSPB said:
‘The benefits of a complete eradication of rats from the Calf are likely to be high – a substantial increase in the numbers and distribution of shearwater burrows and possible re-colonization by storm petrels and puffins. Secondary positive effects on other breeding bird performance and wider biodiversity benefits (invertebrates, plants and even other small mammals) are also likely.’
The project will cost around £48,000, to be jointly funded by the RSPB and Manx National Heritage Trustees, with a contribution towards the cost of rodenticide from DEFA and with in-kind contributions from Fera and other project partners. Donations towards the project, the ongoing protection and monitoring of Manx Shearwaters on the Calf and other conservation work on the island can be made to ‘Manx Museum and National Trust’, Kingswood Grove, Douglas, Isle of Man IM1 3LY.