The Common Pipistrelle Bat (Pipistrellus pipistrellus)

Pipistrelles are the most common and widespread of all British bats. As such, they’re the ones you’re most likely to see while you’re in the garden or out and about.

What Does the Common Pipistrelle Look Like?

The Common Pipistrelle is a small bat, measuring 3.5cm – 4.5cm in length and weighing only 3 grams – 8 grams. Its wingspan ranges from 20cm – 23.5cm.

It has medium to dark brown fur which is a little paler on the chest and belly. Its face is dark and the chest and wings are almost black.

Where Do Pipistrelle Bats Live?

The Common Pipistrelle lives in areas all across the UK. They roost and hibernate in buildings. Either between roofing tiles and felt, soffit boards or eaves boarding, or between cavity walls. They also roost inside the holes in trees as well as bat boxes.

Trees, woodland, and hedgerows are important feeding habitats. When hunting and foraging they tend to follow woodland edges and hedgerows. Pipistrelles often hunt along rivers and other water sources.

What Do Common Pipistrelles Eat?

Flies make up the bulk of the Common Pipistrelle’s diet. They also eat mayflies, mosquitos, midgets and lacewings.

They fly between 2m – 10m above the ground and use their echolocation to find prey which they catch by ‘aerial hawking‘. This means they catch and eat their food ‘on the wing’, or while they’re in mid-flight.

How Do They Breed?

Mating takes place between July and September. During this time, male Pipistrelles roost on their own and establish ‘courtship territories’. They attract female bats by singing social calls called ‘song flights’.

After mating, the sperm doesn’t fertilise the female’s egg until the following spring. This is called ‘delayed implantation’.

Females form maternity colonies of up to 75 bats in early summer, often in a roof space. After a gestation period of 44 – 50 days, they give birth to a single pup in June or July. Pups feed solely on their mother’s milk for the first 3 – 4 weeks. At around 4 weeks, young bats are able to fly and at 6 weeks old, they’re able to forage and hunt for themselves.

Females reach sexual maturity in 1 year. Males reach maturity in 2 years.

When and Where to They Hibernate?

Common Pipistrelles become less active at around October. By December, they are in full hibernation. They prefer to hibernate in buildings and bat boxes where they can take advantage of the warmth and shelter.

When temperatures start to warm up again at around March time, they emerge from their hibernation roosts. By May, they’re fully active again.

What Does Their Echolocation Sound Like?

Most sounds the Common Pipistrelle makes are above the range of human hearing. The only exception might be their social calls which some children might be able to hear.

A bat detector can pick up their echolocation calls between 45kHz – 70kHz.

Threats to the Common Pipistrelle

Populations of Pipistrelle bats have declined a lot in the last few decades. That said, Common Pipistrelle numbers have recovered in recent years.

Still, they face several threats, including;

• Reduced food supply – modern agriculture and the heavy use of pesticides is responsible for a huge decline in insect numbers. The very insects bats feed on.
• Modern building – house renovations often disturb bat colonies. Not only that, but chemically treated timber and insulation is often toxic to bats.

When and Where to See Them

The Common Pipistrelle is the second most common bat in the UK after the Soprano Pipistrelle. You can see them all over the UK and experts predict their numbers to be around 3 million.

They’re most active between April and September so this is the best time to see them. Have a walk around your garden or your local area at dusk. Chances are, you’ll see them flying around above your head, especially if you’re near water.