Bat Surveys


What is a Bat Survey?

A number of different types of bat survey exist. These include surveys for roost sites (resting places), commuting or feeding routes (i.e. where bats travel in order to find food or feed). Surveys include nighttime surveys of a site, concentrated around areas with best habitat potential for bats, or buildings, which might be roost sites. In addition, daytime surveys of potential roost sites such as attic spaces and large trees or stone buildings are completed to look for signs of bat usage such as droppings and stains.

When can Bat Surveys be completed? How long does a bat survey take?
Nighttime bat surveys are optimal during summer months (May – August) when bats are most active. Surveys must be completed in fine, dry weather conditions and so a time limitation in conducting surveys is often waiting for suitable weather. Daytime roost surveys can be completed out of season or in less favourable weather conditions, but generally are accompanied by a nighttime survey. For many sites, a one night (dawn and dusk) survey is completed, but this is dependant on the size of the site, the habitats present and the number of surveyors. If you have a site, which requires a bat survey, contact our office for more details or a specific quotation.

How is a bat survey conducted?
Trained bat professionals walking pre-determined transects or routes using hand held bat detectors usually conduct a nighttime bat survey. The bat detector translates the high-pitched sounds that bats make at different frequencies into identifiable sounds for the surveyor who records the time, location and number of bats as they survey. Direct searching for bats, including use of endoscopes and torches to look into cracks and crevices where bats may have located themselves, completes daytime surveys.

McCarthy Keville O'Sullivan also own equipment to monitor the levels of bat activity automatically. An Anabat bat detector is used on some sites to record the ultrasonic calls of bats. This method has advantages over surveys carried out using hand-held heterodyne bat detectors in some circumstances, particularly where large areas are to be covered, or where there may be safety issues concerning workers covering difficult ground in darkness. The recording device is placed in a waterproof container and is powered by a battery capable of powering the detector for at least one month.

Why are bat surveys required?
All ten species of bat in Ireland are legally protected under the Wildlife Act and are listed on Annex IV of the EU Habitats Directive. In Ireland, the Lesser Horseshoe Bat is listed on Annex II of the EU Habitats Directive requiring more strict protection and designations of its habitat. It is an offence to wilfully interfere with their roosts, breeding sites and resting places. Planning authorities are required to take account of the presence of protected species, including bats, when considering applications for planning permission.

Why would I be asked for a bat survey?
You may be asked to conduct a bat survey if your site contains ruined buildings or large old trees, which provide suitable roosting habitat. In addition it may be necessary to complete a bat survey if your site is adjacent to an area known or protected for it’s bat population or along a potential bat commuting route, e.g. significant woodland, hedgerow system or river.

What if bats are found on my site?
Although the presence of bats does not in most instances preclude a land parcel from development, planning and licensing controls may limit the extent of disturbance, the timing of activities or require bat conservation measures to be put in place. Planning conditions are often used to this end. However, the grant of planning permission does not authorise the disturbance of bats or interference with their breeding or resting places. A separate derogation licence issued by the National Parks and Wildlife Service (NPWS) is required.

McCarthy Keville O’Sullivan have in-house trained bat professionals capable of completing survey work on your behalf. Contact our office for more information.

To download a brochure click the link below
Bat Surveys - General Development.pdf

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