Guidance, published by Natural England in May 2008, recommends that more consideration is given to bat activity within the area of a proposed development, with a minimum of one year of research and activity recording to establish flight and migratory paths.

In order to assess the risk to bats as part of a site assessment process (planning or EIA), appropriate survey objectives need to be set. We advise the following factors are taken into consideration when setting survey objectives and selecting methodologies for planning applications or environmental assessment:

• The primary objective is to determine whether the proposed site is used by, or is likely to be used by bats at any time of the year.
• Efforts should focus on significant concentrations of bats particularly on those species identified as high risk, though all species using the site to any significant extent should be identified.
• Early identification of sites used by significant concentrations of bats enables assessment of risk. Where risk of harm is likely and unavoidable, alternative sites should be considered.
• Establish bat activity across and within the site, locating any roosts on or close to the site. Bats become fairly well dispersed in the landscape within a few hundred metres of the roost, though this depends in part on the species and the type of roost.
• Use of the site throughout the year by bats should be investigated at an early stage, with survey effort focussed principally on those periods when the highest concentrations of bats are likely (April-October in most situations).
• Bats change their activity across the year. Survey effort should be spread across the season to reflect this. Surveys may on occasion need to stretch across more than one year, especially if important roosts are in close proximity to the site.
• Emphasis should be placed on detecting important flight paths across the site and likely to intersect with the turbines.
• Project planning should allow for sufficient time to carry out the bat surveys.

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