Common Pipistrelle (Pipistrellus pipistrellus): Bat Facts

Appearance: how to recognize a pipistrelle

The common pipistrelle is a small, dark bat with medium to dark brown fur on the back and slightly paler, grayish-brown fur below. The face, ears and wing membranes are blackish brown. Its ears are short and triangular, with rounded tips, and the snout is short and broad.

Like all bats, it has wings made of thin skin stretched between very long finger bones, the arm, the body and the legs. A small flap of skin called the post-calcarial lobe sits on the edge of the tail membrane, a feature that helps experts separate pipistrelles from some similar small bats in the hand.

In flight, a pipistrelle looks like a fast, jerky, dark shape about the size of a large moth. It twists and turns quickly over a regular route a few meters above the ground, often along a hedge, tree line, path or street lamp.

How big is a common pipistrelle?

This is one of the smallest mammals in Europe. Typical adult measurements are:

Weight changes a lot through the year. A bat is heaviest in autumn, when it puts on fat for hibernation, and lightest in early spring after living on those reserves all winter. Females are usually a little larger than males. Despite its tiny size, a pipistrelle is not the smallest bat in the world; that title usually goes to Kitti’s hog-nosed bat of Thailand and Myanmar, which weighs about 2 g.

The soprano pipistrelle split

Until the 1990s, scientists counted only one “pipistrelle” in Britain. Bat workers using detectors then noticed that some pipistrelles called at about 45 kHz and others at about 55 kHz. Genetic studies confirmed that these were two separate species, and in 1999 the higher-pitched bat was formally recognized as the soprano pipistrelle (Pipistrellus pygmaeus).

The two are so alike that they are called cryptic species. Differences found since the split include:

• Echolocation: common pipistrelle calls peak at about 45 kHz, soprano pipistrelle calls at about 55 kHz.
• Habitat: soprano pipistrelles feed more over rivers, lakes and wetland woodland; common pipistrelles use a wider range of habitats, from farmland to town centers.
• Colonies: soprano pipistrelles tend to form larger nursery colonies, sometimes of several hundred bats or more.
• Diet: sopranos eat more aquatic midges, while common pipistrelles take a broader mix of flies.

Because older records do not separate the two, statements such as “the most common bat in Europe” written before 1999 refer to both species together. Europe also has other pipistrelles, including Nathusius’ pipistrelle, a long-distance migrant, and Kuhl’s pipistrelle of southern Europe.

Habitat and range

The common pipistrelle lives across most of Europe, from the British Isles and Iberia east through Central Europe, north to southern Scandinavia and southern Finland, and south to the Mediterranean islands and parts of northwest Africa. Its range continues through the Middle East and the Caucasus into parts of Central and South Asia.

It is a true generalist. It hunts along woodland edges, tree lines, hedgerows, parkland, rivers and ponds, and it is one of the few bats that does well in towns and suburbs. Studies show it likes “edges”, such as the line where a wood meets a field, because insects gather there and the bat can use the linear feature to navigate.

For roosting, it chooses tight crevices. In summer it uses gaps in buildings, behind boards, tiles and cladding, as well as tree cracks and bat boxes. In winter it hibernates singly or in small groups in cracks in buildings, trees and occasionally rock, rarely in large caves. Read more about roost types in Where do bats live?.

Diet and echolocation

The common pipistrelle is an insectivore that catches almost all of its food in flight. Its main prey are small, soft-bodied flies, especially non-biting midges, gnats and mosquitoes, along with small moths, caddisflies, mayflies and lacewings. It typically leaves the roost about 20–30 minutes after sunset and feeds in several bouts through the night.

The Bat Conservation Trust estimates that a single pipistrelle can eat up to about 3,000 tiny insects in one night. Because the prey are so small, that is far less impressive by weight than it sounds: the total is roughly a quarter to a third of the bat’s body weight on a good night. See How many insects does a bat eat in a night? for how scientists reach such numbers.

The bat finds its prey by echolocation. It produces short calls through its open mouth and listens for the echoes. Search calls sweep down from about 70 kHz to around 45 kHz, where most of the energy lies, and last about 5–6 milliseconds. When it closes in on an insect, the calls speed up into a rapid “feeding buzz”. Humans cannot hear these calls without a bat detector, which makes them sound like wet slaps or clicks.

Behavior and social life

Common pipistrelles are social bats. In summer, pregnant females gather in nursery (maternity) colonies, usually of a few dozen to a couple of hundred animals, while males and non-breeding females live alone or in small groups. Colonies often move between several roosts in the same area during the summer.

In late summer and autumn, males set up mating territories, often near roosts that females visit. Each male makes repeated song flights over his patch and gives loud social calls, partly audible to young people, to attract females. Some males also call from a roost entrance. Females visit several territories, so the system works somewhat like a lek, where females choose among displaying males.

From about November to March or April, pipistrelles hibernate. Their body temperature falls close to that of the surroundings and their heart rate drops sharply. They wake now and then, and on mild winter nights they may even fly out to feed, which is why pipistrelles are among the bats most often seen in winter. Read more in Do bats hibernate?.

Reproduction and life cycle

Mating takes place in late summer and autumn, but females store the sperm through the winter. Ovulation and fertilization happen only in spring, after hibernation. This delay lets females time the birth for early summer, when insects are most plentiful.

Pregnancy lasts roughly six to seven weeks after fertilization, depending on the weather. Births happen mostly in June and early July. Each female usually has a single pup, though twins occur in some populations. Newborn pups are naked and pink and weigh around a fifth of their mother’s weight.

Mothers leave their young in the roost while they hunt and return to suckle them. Pups grow fast, fly at about three to four weeks old and are weaned by August. Females can breed in their first year. Because each female normally raises only one pup a year, pipistrelle populations recover slowly from losses.

Lifespan, predators and threats

Most common pipistrelles live about four to five years, but ringing studies have recorded individuals surviving about 16 years in the wild, a long life for such a small mammal. Hibernation and the low risk of predation in flight help explain why bats live much longer than mice of the same size.

Natural predators include owls, sparrowhawks and hobbies, along with mustelids that reach roosts. Domestic cats are a significant cause of bat casualties around houses in Britain. Other threats include:

• Loss of feeding habitat: removal of hedges, ponds and tree lines and intensive farming reduce insect numbers.
• Roost loss: building repairs, re-roofing, insulation and demolition can destroy or seal roosts.
• Pesticides and timber treatments: these reduce prey and, in the past, poisoned bats in roofs.
• Artificial light: bright lighting near roosts can delay emergence and break up flight routes.
• Wind turbines and roads: collisions kill some bats, including pipistrelles.

Conservation status and legal protection

The IUCN lists the common pipistrelle as Least Concern because it has a very large range and a large population, with no sign of a rapid global decline. In Britain, monitoring by the Bat Conservation Trust has shown its numbers to be stable or increasing in recent decades, after earlier declines linked to agricultural change.

All bats in the UK and EU have strong legal protection. In Great Britain this comes from the Wildlife and Countryside Act 1981 and the Conservation of Habitats and Species Regulations 2017. In the EU, all bat species are listed on Annex IV of the Habitats Directive, and many European countries also cooperate through the EUROBATS agreement. In practice, it is an offense to deliberately disturb, injure or kill bats, or to damage, destroy or block access to a roost, whether or not bats are present at the time. Anyone planning building work that might affect bats should get advice from the national nature agency or a bat group first.

Myths and facts

Myth: pipistrelles damage houses. Bats do not gnaw, build nests or bring in material. Their droppings are dry pellets made of insect remains that crumble to powder and do not usually spread disease in this form.

Myth: bats get tangled in hair. A pipistrelle’s echolocation is precise enough to catch a midge in the dark. Bats sometimes fly close to people because insects swarm around them, but they do not land in hair.

Myth: the bats in my roof are mice with wings. Bats are not rodents. They belong to their own order, Chiroptera, and are more closely related to hedgehogs, carnivores and hoofed mammals than to mice. Learn more in Are bats mammals?.

Relationship with people

For many people in Europe, the pipistrelle is the bat they know best: the small dark shape that flits along the street or over the garden on summer evenings. Bat walks run by local bat groups often begin with pipistrelles because they emerge early and fly in the open.

Gardens can help pipistrelles by keeping trees and hedges, adding a pond, growing night-scented flowers that attract moths and other insects, and keeping outdoor lights low and dim. One famous example of people valuing pipistrelles comes from Portugal, where a colony of small bats has long been allowed to live in the historic Joanina Library at the University of Coimbra, feeding at night on insects that could otherwise damage old books.