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Bats just love midges

The bat survey season is well underway with some 20 activity surveys undertaken by our team of trained bat surveyors to date. They are hard souls surviving the onslaught of midges and clegs as they carry out dusk and dawn surveys around the country. We’ve recorded Common and Soprano pipistrelles as well as Daubenton’s bats found close to water and Brown long-eared bats emerging to feed in dense woodland.

We work closely with clients and home owners to establish the species, numbers, type of roost and access and egress points from roost features. This information allows them to undertake the work whilst minimising the disturbance to the bats present. Usually the roosts, in the case of Pipistrelles, are on the outside of buildings under slates, facias and flashings. Our bigger bats tend to be found inside lofts and in the case of Daubenton’s bats under bridges in slots and cracks in old masonry. These pipistrelles were relocated as part of a renovation of an old steading, placed in a bat box which they will occupy until the renovation was complete.

A brace of Pipistrelles rehoused

Bats in the UK are insectivorous feeding in and around woodland and water where insect numbers are greatest (Brown long-eared (Plecotus auritus) and Pipistrelles (Pipistrellus spp.) are 2 of our most common bats). Common Pipistrelle exploit a wide range of habitats including watercourses, woodlands, grassland and built up areas. We use bat detectors to record the bat’s echolocation calls and with some smart software are able to identify the species of bat from the shape and frequency of the call eg Common pipistrelle echo locate at 43-49kHz whereas Soprano pipistrelle call at 50-64kHz. They use echolocation to navigate and to hone in on flying insects with great accuracy.

Bats are colonial animals which can live in large groups at some times of the year with pregnant females forming nursery colonies in spring usually early to mid-May. The young are born mid-June to July and they are reared in summer roosts usually in warm sheltered buildings before the colonies disperse in August and September (October to November for long-eared bats). Flightless young are left inside the roosts during the summer period making maternity colonies particularly vulnerable to disturbance. Males and immature females live in small groups or solitary during summer often in cool roost sites such as barns, houses or trees. Pipistrelles are known to move between different roost features on the one structure and will often leave the young bats soon after they are weaned at 4-5 weeks.

Winter roosts or Hibernacula are selected for constant temperatures (5-10 degrees), high humidity, shelter and protection from disturbance. Some buildings which contain deep crevices in wallheads or cellars may provide suitable sites (mainly for pipistrelle or long-eared bats) but the other Scottish species rarely hibernate in buildings.

Pipistrelle bats are reckoned to eat 3000 midges a night which is all the more reason to make space for them in our homes.


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