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SSSI Guidelines: Chapter 16. Mammals 2022


Guidelines for the Selection of biological SSSIs

Part 2: Detailed guidelines for habitats and species groups

The statutory nature conservation agencies have a duty under the Wildlife and Countryside Act 1981, as amended, to notify any area of land which in their opinion is 'of special interest by reason of any of its flora, fauna, or geological or physiographical features'. Such areas are known as Sites of Special Scientific Interest (SSSIs).

This Chapter covers mammal species. Site selection for species and assemblages should be based on stable populations, however, as many threatened species are experiencing severe declines this approach should be used as a guideline only and there may be justification for the selection of species and assemblages in unfavourable condition.

As part of the revision process of Part 2 of the SSSI Guidelines, an updated and revised version of this chapter was produced in 2019 (Version 1). Version 1.1 was subsequently produced in December 2022, to remove the separate section on seals (which wasn't updated in 2019), following agreement by specialists and chief scientists in the statutory nature conservation bodies that the section was no longer required. No other changes were made.

For more information about the SSSI Guidelines, and to access the other chapters, visit the SSSI Guidelines webpage.

This resource may not be fully accessible for all users. If you need a copy in a different or more accessible format, please contact

Resource type Publication

Topic category Environment

Reference date 2022·12·01

Walsh, K., Matthews, J., Halliwell, E., Morris, K., Raynor, R. & Bryce, J. 2022. Guidelines for the selection of biological SSSIs. Part 2: Detailed guidelines for Habitats and Species. Chapter 16 Mammals (version 1.1). JNCC, Peterborough.

Version 1 of this chapter was published in 2019, and replaces the original Mammals SSSI Selection Guidelines chapter (Nature Conservancy Council 1989). Version 1.1 was produced in December 2022.

Responsible organisation
Communications, JNCC publisher

Limitations on public access No limitations

Use constraints Available under the Open Government Licence 3.0

Metadata date 2022·12·19

Metadata point of contact
Communications, JNCC

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