A client got in touch with Arbtech who needed a preliminary roost assessment (PRA) on their house as requested by Chichester District Council when they submitted their planning application.
The development proposal was for the demolition of an existing extension and addition of two new two-storey extensions.
About the area
The site is located in Birdham within the Chichester Harbour Area of Outstanding Natural Beauty (AONB). Chichester Harbour is also designated as a Site of Special Scientific Interest (SSSI) and the area also includes Chichester to Langstone Harbours Special Protection Area (SPA) and Ramsar Site, and Solent Maritime Special Area of Conservation (SAC).
The surveyor inspected the building inside and out, visually inspecting all loft voids and all external features of the building. Any evidence of bat use and all suitable roosting features were noted and mapped. Bat droppings were collected for DNA analysis.
Evidence of bat roosting was found in the loft voids where bat droppings were found scattered on the floor and stuck to walls. Externally on the building high value roosting features were identified in the form of clay hanging tiles. This style of hanging tile provides ideal roosting habitat for crevice dwelling bats, particularly common and soprano pipistrelles. Further evidence of roosting was found in these areas with droppings stuck to hanging tiles.
Bat emergence and re-entry surveys
When evidence of bat use or suitable bat roosting habitat is found, this means that further surveys are required to establish presence/likely absence of bat roosts, or to characterise the bat roosts that are there. The surveys are undertaken at dusk or dawn with surveyors sited around the building with bat detectors.
All elevations will need to be observed at the same time so multiple surveyors are required. The surveyors will watch the bats emerge from the roosts at dusk, and return to the roosts at dawn, and will determine each species based on its echolocation which is picked up by the bat detectors.
The surveys will record which species of bats are present roosting in the building, in what numbers and the roost types. General bat activity around the site will also be recorded. The surveys can be carried out between May and September when bats are most active.
The surveys were carried out in August and September and confirmed multiple day roosts of common and soprano pipistrelles under the hanging tiles.
What happened next
Following the completion of the surveys, the report was submitted to the council. This outlined the mitigation and the requirement for a European protected species mitigation licence (EPSML). At this point the council could approve the proposal with no further ecology work needed to inform the planning application.
The EPSM licence needs to be applied for prior to the start of the work to the bat roosts, this is usually within 3 months of the start of work. The licence can only be applied for once planning consent has been granted. The licence is required to legally carry out work to a bat roost.
Arbtech prepared and submitted the licence application to Natural England in the months running up to the start of the work. As part of the licence conditions the strip of the hanging tiles had to be carried out by hand under ecological supervision, and any bats found would be moved to bat boxes that have to be installed on trees on site.
New roosting habitat was created in the new extension in the form of integrated bat boxes built into the wall during construction.