Echolocation
To distinguish them from soprano pipistrelles they are often referred to as ‘45s’. Although social calls and chatter in the roost are audible, their echolocation calls are ultrasonic. On a bat detector they can be heard as a series of clicks and slaps, with the peak intensity of the call at about 45 kHz on average. Pipistrelles with peak frequency in the range 42 to 49 kHz are classified as common pipistrelle.
Habits
Naturally a tree-dwelling animal, the common pipistrelle has adapted well to living alongside people. This is the species you are most likely to see in your garden, twisting and dodging with an erratic flight path as it catches tiny insects in flight. It feeds mainly on a wide range of small flies as well as aquatic midges and gnats, typically within two kilometres of its roost. It forages in a range of habitats including woodlands and gardens and frequently forages along edge habitats such as hedges and tree lines.
Summer roosts of females are often in tight spaces on the outside of our houses, including modern ones. They also roost in buildings, tree cavities, and some underground sites. They may be seen flying during the winter on mild days.
Reproduction and life cycle
Popular spots for maternity roosts are under hanging tiles and weather boarding, behind barge boards or between roof felt and tiles. The maternity colonies move around quite regularly between different roost sites. The young are fed solely on mothers’ milk for three or four weeks. After about four weeks they start to fly and at six weeks are able to forage for themselves. Once the young are foraging the maternity roosts start to break up.
Their audible chattering can often be heard just before they emerge, about 15 minutes after sunset, and it can be exciting to watch them return at dawn, though householders may previously have been unaware of their presence.
Males usually roost singly or in small groups. In late summer and early autumn they defend mating roosts to which they attract females by making ‘song flights’ and social calls as they fly.
Distribution, status and conservation
Common pipistrelles are widespread throughout the UK and the rest of Europe, but nationally numbers declined dramatically over the last few decades. Although populations have started to show signs of recovery in more recent years, they are nowhere near the level of 50 years ago. According to the NBMP 2024 populations are now under long-term increase and a stable short-term trend.
Car survey records have confirmed common pipistrelles as the most abundant bats in Kent, but they are still vulnerable to loss or severance of habitat, through development and transport links, as well as light pollution impacts.
As the species most likely to be seen in or near our homes, we can help increase its food supply by careful garden planning. Extending the period when a wide range of nectar-rich flowers are in bloom, and leaving some grass to grow as food for insect larvae, can make a real contribution to helping bats.
