The recorders of the main groups in the Yorkshire Naturalist Union and the Halifax Scientific Society were contacted and their views sought as well as requests for extra information relevant to the district. In addition records were extracted from West Yorkshire Ecology and the Countryside and Forestry’s Unit (now Countryside Service) Recorder database. The draft Audit was then circulated for consultation to organisations with an understanding of species distribution in Calderdale.
The following tables list all those species which have been recorded in Calderdale Metropolitan Borough District and which meet the following criteria. The species identified as Calderdale Priority Species are identified in the notes. In order to exclude species no longer present, only records more recent than 1950 are included. As far as it is possible to determine, all records have been authenticated by recognised naturalist recorders.
Species of National Importance
All those species known to occur in Calderdale that are of national importance are listed. They include species that are:
- Listed by the UK Biodiversity Action Plan as a Priority Species or a Species of Conservation Concern.
- Listed in a national Red Data Book or, for birds, on the Birds of Conservation Concern ‘Red’ or ‘Amber’ lists (RSPB, 2002).
- Not listed in a Red Data Book but authoritatively recognized as of national importance.
Species of Regional Importance
Species occurring in Calderdale that are regarded to be of regional importance are listed. Little quantitative information is available about species of regional importance. However the Yorkshire and Humberside Biodiversity Forum are in the process of producing a regional audit of species (Knight, 2002).
Species of Local Importance
Those species that do not meet the national or regional criteria have been assessed according to the following criteria:
- Rare: restricted to 3 sites or less.
- Declining: believed to be declining to the extent that their survival in Calderdale is threatened.
- Endangered: confined to sites and habitats particularly threatened by development or land management.