Report 339
Seabird monitoring on Skomer Island in 1999-2002
Brown, J.G., Perrins, C.M., Boyle, D., Duffield, S., Dustan, A., Easton, J., Smith, S. & Parsons, M.
This report details the results of seabird monitoring studies commissioned by the JNCC on Skomer Island National Nature Reserve in 1999-2002 and carried out by the Wildlife Trust of South and West Wales (formerly the Wildlife Trust West Wales) and Edward Grey Institute of Field Ornithology. For completeness and ease of reference, the results of additional relevant seabird monitoring studies undertaken on Skomer over the same period by the Wildlife Trust West Wales are included.



Seabirds are a significant component of the marine environment and Britain has internationally important populations of several species. A national Seabird Monitoring Programme (SMP), co-ordinated by the Joint Nature Conservation Committee (JNCC), includes a small number of "key site" seabird colonies where detailed monitoring of breeding success, annual survival rates and population trends is carried out. These sites are geographically spread to give as full a coverage of British waters as possible.


Skomer Island is the most suitable site for this work in south-west Britain. It is a National Nature Reserve managed by The Wildlife Trust of South and West Wales (WTSWW) under a lease from the Countryside Council for Wales (CCW). The island is part of the Skokholm and Skomer Special Protection Area (SPA), designated because of its seabird interest, and the waters around the island have been designated a Marine Nature Reserve. Seabird monitoring fits within a broader framework of monitoring marine and terrestrial organisms on and around the island.


There also exists a long-term data set for seabirds on Skomer, which is invaluable in setting current results in context. This is especially important for species such as seabirds with long periods of immaturity and high adult survival rates. The Wildlife Trust has been monitoring seabirds on the island since the early 1960s, while the Oxford University Edward Grey Institute of Field Ornithology (EGI) has monitored populations and adult survival rates of burrow-nesting species and gulls on the island for over two decades.  Other bodies have carried out additional studies of individual species.


This report documents the work undertaken in 1999-2002 by WTSWW and EGI on behalf of the JNCC and CCW. Specifically, the work was divided as follows between the two contractors.  Whole-colony and study plot counts were undertaken by WTSWW, except the study plot count of Manx shearwaters, undertaken by EGI; breeding success was studied by WTSWW, except for Manx shearwater and lesser black-backed gull, which were undertaken by EGI; adult survival rates were studied by EGI, as was feeding rate of Atlantic puffins.  The report also includes data on numbers of European storm petrels Hydrobates pelagicus, European shags Phalacrocorax aristotelis, great cormorants P. carbo and Atlantic puffins Fratercula arctica and on breeding success of razorbills Alca torda collected by WTSWW without external funding assistance. Information about some of this additional work is also published elsewhere by WTWW, e.g. in The Island Naturalist - the Journal of the Friends of Skomer and Skokholm and the annual Puffin Pal reports. Further details may be obtained from the WTSWW at the address given on the title page.

ISSN 0963-8091
Please cite as: Brown, J.G., Perrins, C.M., Boyle, D., Duffield, S., Dustan, A., Easton, J., Smith, S. & Parsons, M., (2004), Seabird monitoring on Skomer Island in 1999-2002, JNCC Report 339, ISSN 0963-8091