Bat Surveys of Buildings

We conduct bat surveys of buildings throughout Wales, northern England and Scotland.

Many British bats have adapted to roosting in buildings. Features such as roof voids, gaps between sarking and slates, cracks and crevices in the walls, gaps above the wall head, ridge tile/stones, facia boards, lead flashing, hanging tiles, wood cladding and gaps in to the soffits can all be suitable for roosting bats.

UK legislation requires landowners and developers to carry out a bat survey prior to modification or demolition of buildings suitable for roosting bats.

This page describes the methodology for surveying and assessing a building’s potential for roosting bats.

Methodology

This methodology is agreed as best practice by NatureScot, Natural Resources Wales, Natural England and the Bat Conservation Trust.

Stage One: Visual Inspection – Also known as a Preliminary Bat Roost Assessment (PRA)

All buildings are inspected on the inside and outside during daylight hours by a licensed bat worker with the aid of strong torch light and an endoscope looking for evidence of roosting bats, including live bats, remains of dead bats, droppings, feeding remains and possible roosting sites. Special attention is paid to any cracks, crevices and holes in walls and ceilings.

Buildings are also assessed for potential to be used by roosting bats in the future and allocated to one of the following categories:

• Confirmed: Confirmed signs of bat presence/occupation and actual bat presence;
• High Potential: Features present with high potential to support roosting bats. These include structures with points of access to the interior through degraded/ missing mortar/ brickwork, proximity to good foraging habitat such as woodland and/ or water and suitable crevices, dense ivy cover;
• Moderate Potential: Features present that are able to support small numbers of roosting bats such as males in the summer or the winter;
• Low Potential: Limited roosting potential. Structures in good condition with no access into structure visible. Few features of bat interest; and
• Negligible: Roosting bats very unlikely to be present. Includes structures constructed from unsuitable materials e.g. prefabricated steel with no entrance opportunities.

Visual inspections can be conducted at any time of year.

All buildings assessed as having high potential for roosting bats should have a bat activity survey conducted between May and September inclusive.

Stage Two: Bat Activity Surveys

It is recommended that a bat activity survey is conducted for all buildings assessed as having potential for roosting. Bat activity surveys can take place any time between between the months of May and September inclusive (please note that bat activity surveys and will include dusk survey observing bats leaving at dusk and dawn surveys observing bats re-entering the buildings. all activity surveys are conducted with the aid of Anabat Scout bat detectors.

Dusk emergence counts start half an hour before dusk and finish approximately 1.5 hours after dusk. The number of bat workers required to carry out the survey will depend on the number of elevations and complexity of the roofs of the survey site.

It is usual for at least two emergence counts to be conducted, approximately two weeks apart, in order to have enough information to determine the status of the building.

Dawn re-entry surveys start two hours before dawn and ends at sunrise. As with the emergence count, the number of bat workers required to carry out the survey will depend on the number of elevations and complexity of the roofs.

Numbers, species, emergence/entry times and exit/entrance holes are recorded using plans of the property, digital photography and infra-red cameras.

Where possible it is also recommended that a static remote Anbat Express is left inside a roofvoid or barn for several night.

As previously stated, activity surveys can only take place between the months of May and September inclusive. However, current best practice dictates that activity surveys can not usually be started and finished in September as some roosts will have dispersed by then and could be missed.

Licenses to disturb a European Protected Species

Where possible, it is recommended that proposed developments avoid all buildings with confirmed roosts or those identified as having high potential for roosting bats.

However, if this is not possible a European Protected Species (EPS) license to disturb/destroy the confirmed bat roost(s) will be required from Scottish Natural Heritage, Natural Resources Wales or Natural England before any work on the buildings can commence.

A Bat Protection Plan (BPP) is required as part of the application process.

Stuart Spray Wildlife Consultancy can prepare BPPs and guide you through the licence application process.