British Bats

Bats have traditionally in western folklore been being painted in a bad light, as creatures of the night. However in the east they are considered harbingers of long life and good luck.

Bats are the only mammals that have evolved true sustained flight. The bat was once known as the flittermouse due to its flittering flight.

All british bats are insectivorous. British bats are divided into two groups, the horseshoe bats and the typical bats.

Bats are nocturnal animals; they hunt during the night and then roost during the day.

Bats rather than migrating to escape the cold winter, they hibernate. They build up reserves of fat under the skin, on which they rely on over the lean winter period. The hibernation is only a partial one, the bats only go into a torpor. In this way they reduce their winter energy requirements.

British bats do not maintain a constant body temperature, instead they can vary it. At rest they reduce their temperature to that of the ambient background. This temperature reduction leads to a lower metabolic rate and therefore saves energy. On the down side this make them lethargic and prone to predators while in this state, and therfore their roosts need to be secure or hidden. Before they go out for their nocturnal hunt they have to increase their body temperature.

Temperature is of overiding importance, hence throughout the year, roosting spots will change dependant on the season.

Bats painstakingly groom their fur and clean their wings, both during the day and night. This is essential for the fur to retain its insulating properties.

Many british bats only have a solitary youngster, this low breeding rate means that colonies require to be protected. If a colony is destroyed, the population takes a long time to recover if indeed they ever do. It is fortunate that bats have a long life span, which can be 20 years plus.

Bats have greatly elongated finger joints which provide the framework over which the skin is tightly stretched creating leathery wings.

This wing design provides great flexibility, as the fingers are able to subtly change the wing shape. The flight that the wings provide is not as fast as that of birds but enables greater manoeuvrability.

A constraint of the wing design is that the primary use of their limbs is flight. The limbs are not muscular enough to be used for standing upright; bats instead rest hanging upside down.

Bats use echo-location to locate their prey and navigate around obstacles. Bats emit high pitch pulses which are too high for the human ear to hear.

These pulses when they hit an obstruction or prey are partially reflected as an echo, which is then picked up by the ears. This is the reason why bats have large ears, which is particularly so with the long eared bats.

   Pipistrelle  Pipistrellus pipistrellus

   Long Eared Bat  Plecotus auritus

   Noctule Bat   Nyctalus noctula

   Natterer's Bat  Myotis nattereri

Pipistrelle Pipistrellus pipistrellus

The smallest and most common British bat is the pipistrelle. A small heavy built bat with a pug dog face. The pipistrelle is typically reddish brown, but can vary from light brown to black.

As its prey is small insects, its teeth are required to be small and very sharp.

When hunting insects it flies fast, continually twisting and turning, giving it, its distinctive erratic flight pattern.

During the night, the pipistrelle can have several temporary roosts. Here they rest and digest their catch before continuance of the hunt, eventually returning to their daytime roost.

Roosting patterns vary depending on the season. In summer females with young form their own colony, while the males roost in solitude. The winter hibernation roosts comprise of both sexes.

The pipistrelle has an interesting breeding pattern. In autumn they mate, but fertilisation of the female does not occur until spring. The young are born, one per female later in June, the actual time depending on the weather conditions. As favourable feeding conditions are required to provide the best chance of survival for the young.

Long Eared Bat Plecotus auritus

The most distinctive of British bats. With their long ears they cannot be mistaken for any other species. They are the largest of British bats.

Bats use echo location to hunt, the long eared bat has finely tuned this process. Its large ears not only enable it to catch flying prey but also non flying. The ears can discriminate the echoes from the background that the prey is located on, from those reflected off the prey’s body itself.

Females in the summer roost in single sex colonies with their young. Females only have a single youngster, which is born between June and July.

As well as advantages, the large ears can provide problems. Their large ear size means that they have a large surface area, through which vital heat and moisture are lost.

Noctule Bat   Nyctalus noctula

This is a relatively large bat covered with with fox brown fur. Its flight pattern is fast with many steep dives.

They breed once a year, the females collecting in one sex nurseries, giving birth to up to three young.

Natterer's Bat   Myotis nattereri

This bat has greyish fur on the topside with white underparts. It is a medium sized bat with slow flight.

In Summer, birth is given to a single young, the females roosting together in nursery roosts.