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Manx shearwater Puffinus puffinus evening rafting behaviour around colonies on Skomer, Rum and Bardsey: its spatial extent and implications for recommending seaward boundary extensions to existing colony Special Protection Areas in the UK 2008

Abstract

This report presents recommendations in support of setting of site-specific seaward boundary extensions to three SPAs which have been designated for their internationally important concentrations of Manx shearwaters Puffinus puffinus, namely the Skomer and Skokholm SPA, Rum SPA, and Glannau Aberdaron and Ynys Enlli/Aberdaron Coast and Bardsey Island SPA. These SPAs include the UK’s three largest Manx shearwater colonies, together hosting up to 90% of the world’s population.

Any seaward boundary extension to an existing seabird colony SPA should include marine areas on which the existing interest feature (in this case, breeding Manx shearwaters), are ecologically dependent. Breeding Manx shearwaters regularly form aggregations at sea (called rafts), up to 10 km from the colony shore in the evening, prior to coming ashore to feed the chick after night-fall. Although the function of rafting is not known for certain, it is clearly an important behaviour, given the number of birds that engage in it, and the fact that rafts are regularly formed around the colony.

It is not possible to use conventional visual survey techniques to assess the locations of rafting birds (primarily because rafts are formed in the evening through to nightfall). This report describes work using radio-telemetry to locate key areas used regularly in the evening by rafting Manx shearwaters around the three breeding colonies of Skomer (south-west Wales), Rum (western Scotland), and Bardsey (west Wales). Fieldwork was carried out between July and August, in 2003 (Skomer), 2004 (Rum) and 2005 (Bardsey), with radio-tags fitted to 30, 28 and 30 breeding adults at each colony respectively. Radio-tracking was carried out from early evening until birds returned to their colonies after nightfall, and locations of rafting birds were generated through analysis of radio-tracking data.

Resource type Publication

Topic category Environment

Reference date 2008··

Citation
McSorley, C.A., Wilson, L.J., Dunn, T.E., Gray, C., Dean, B.J., Webb, A. & Reid, J.B. 2008. Manx shearwater Puffinus puffinus evening rafting behaviour around colonies on Skomer, Rum and Bardsey: its spatial extent and implications for recommending seaward boundary extensions to existing colony Special Protection Areas in the UK. JNCC Report No. 406, JNCC, Peterborough.

Lineage
This report presents data in support of seaward extensions to existing seabird breeding colony SPA boundaries.

Responsible organisation
Communications, JNCC publisher

Limitations on public access No limitations

Use constraints Available under the Open Government Licence 3.0

Metadata date 2020·05·27

Metadata point of contact
Communications, JNCC

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