Project Background

Knight Frank on behalf of a private client sought permission to change the use of a building from its former use as a children’s nursery to a residential dwelling. Ecology by Design was commissioned in August 2015 to carry out the necessary bat surveys and again in 2017 because work had not commenced since the original surveys and were now considered out of date. 

Survey Background

The proposal was to replace the false ceiling within the nursery with a mezzanine floor to create a two-storey house, various single-storey extensions were also planned to be demolished and replaced. For these works to go ahead planning permission was required. Due to bats and their roosts being protected by UK and EU law, bat surveys were necessary as part of the planning permission. An initial preliminary roost assessment (PRA) was carried out in 2015 which identified several potential access features and seven dead pipistrelle bats inside the building. Two emergence surveys were then carried out which identified soprano pipistrelles emerging from the building. Planning was granted however the surveys were only valid for two years and therefore were subsequently updated in 2017.

Survey Method

The preliminary roost assessment in 2017 discovered similar potential access features as in 2015 and therefore two dusk emergence and one dawn re-entry survey was carried out. Surveyors were located all around the building focusing on features identified in the preliminary roost assessment. 138 soprano pipistrelle were recorded emerging from the building which was indicative of a maternity roost. Brown long eared and soprano pipistrelle bats were also seen emerging from the neighbouring attached property which anecdotally partially connected to an inaccessible roof void above the nursery.

Outcome

In order for the works on the nursery to proceed lawfully in regards to bats and within the conditions of the planning permission a Natural England licence was required. The maternity roost was considered to be of county importance and of moderate conservation significance due to the type and size of the roost. Without mitigation the works would result in the destruction of a maternity roost and potentially also affect bats from the neighbouring property if they were using the connected inaccessible void above the nursery. A derogation licence will therefore be applied for which will allow for the temporary exclusion of the existing roost during a time when bats are less active and not breeding. Areas close to the roosts will be soft stripped by hand. The roost will not be destroyed but will be made smaller to accommodate the nature of the works. Therefore, as an enhancement two new roosts in the form of bat boxes will be installed on a nearby tree and two raised tile features and a raised ridge tile will be installed on the building. The site will be monitored for three years post development due to the impact on a maternity roost.