Essex Biodiversity Project
Identification - There are 2 sub species of this bat which can be identified by their high pitch squeaks (echo location calls) 45kHz and 55kHz (Kilohertz - method of recording sounds) Pipistrelles are small brown/ grey bats up to 45mm long. They have a wingspan of 220 - 250mm and the forearm part of the wing is 31 - 37mm. Their ears do not join over the top of their heads and they do not have a nose flap. They are the most common bat in the British Isles. A licence is needed to handle all bat species and also for some surveys.
General ecology - Pipistrelles are a common species and are widespread throughout Britain. They inhabit a variety of buildings such as churches, modern houses and also bridges and walls. They do move between roosting sites. They forage (hunt) for food in a diverse range of habitats: woodland, urban parks and gardens, lakes, ponds and marshy areas. They feed on airborne insects at 20 - 30 minutes after sunset and occasionally before. They have a fast, erratic flight pattern at head height.
Although pipistrelles are the most abundant bat they have suffered from a 70% decline between 1978 and 1993. Their main threats are loss of food source (reduction in insects) , loss of insect habitat, loss of flight line features such as hedges and loss or disruption to roost sites.
Surveying tips - The best time to survey for bats is in June for a colony count and August for sunrise survey - just before sunrise! Surveys that might cause disturbance to the bats require a License from Natural England. Use a bat detector to hear them when they are flying and this will cause no disturbance.
Essex Bat Group has developed a Pipistrelle recording card. See the Essex Bat Group on the web and contact them for more details.