Catalogue description Nature Conservancy Council and English Nature: British Bats Dataset

Logical Structure and Schema: The Bats datasets consist of a main table (Batdata), containing the details of the bat enquiry, together with a number of lookup tables which provide translation of the various encoded fields. Further details are available in the dataset catalogues.

Validation: Details of the content and transformation validation checks performed by NDAD on the Bats datasets are contained in the catalogues of individual datasets in the Dataset Catalogue.

Constraints on the reliability of the data: It is important to note that as it is a system which depends on the voluntary submission of records rather than a structured survey methodology, there is no doubt that some interesting and important data will not have been gathered and that data will be inherently biased. Species which can be easily identified may be recorded more frequently than others which are less obvious. The data is biased towards species which frequent buildings. However as well as collecting data arising from enquiries, information is also collected by the conservation agencies about bats in underground sites, such as caves and mines, although coverage here is less complete. However to some extent, this data is complementary and for species which use buildings in the summer and underground sites in the winter the dataset has the potential to provide very good coverage.

In 1981, the Wildlife and Countryside Act extended protection for wild creatures and plants and in particular legislated for the comprehensive protection of 15 species of bat. The Act also coincided with an increased public awareness and interest in their conservation. The legislation ruled that it was illegal to intentionally kill, injure or take any bat, as well as damage, destroy or obstruct access to any place used by bats for shelter and protection or to disturb any bat while roosting. It also made it illegal to sell, hire, barter or exchange a bat whether alive or dead and keep bats in captivity.

One requirement of the Act is that those who wish to rid their house of bats or wish to carry out works that affect bats or their roosts must first contact the appropriate government agency responsible for nature conservation to inform it of the proposed action and allow it time to provide advice. Since 1982, local bat groups, composed of amateur enthusiasts, have been formed in most counties in Scotland, England and Wales, with the primary aim of promoting bat conservation. Their major activity has been to visit sites where bats or their roosts appear to be threatened and either provide on-the-spot conservation advice or collect information about the problem so that appropriate advice can be provided by the appropriate government department. This system of site visits in response to problems has provided a fruitful source of information about bats and their roosts. The great majority of enquiries received relate to problems with bats in houses or, to a lesser extent, other buildings, such as churches or factories. Some data is also gathered in relation to planning development such as road schemes. However only a very small number of enquiries have been about bats in other roosts, such as trees, mines, caves or bridges. The data received is therefore heavily biased towards those species found in buildings. A small amount of information comes from unsolicited visits to buildings to survey for bats, but this is insignificant compared with that received from enquiries.

Once advice is sought by the public from a bat group or from one of the three conservation agencies in England, Scotland and Wales, a volunteer or government employee visits the site where advice is required. From 1982 onwards all such visitors have been requested to fill in a form giving details of the problem and the bats or bat roost involved. These forms are then collected and a summary of the data added to a computerised Bats Database. Visitors are required to identify the species of bat wherever possible, either from a specimen, from droppings or from other characteristics of the roost. The method of identification is also noted on the form as some species can be identified relatively easily, even from droppings, whereas others are more difficult, even with the specimen in the hand. Other information requested includes name and address of roost and owner, details about the building and the roost site, description of the problem, potential threat to the roost, attitude of owners, the extent of usage by bats and the National Grid Reference of the site. Information gathered by surveyors but not included in the dataset include a sketch drawing of the roost. Recommendations for action are also included. Not all the data could easily be handled by the database system, but essential data about species and location were added in a coded form so that searches for records of selected species or selected areas could be carried out relatively easily.