Lesser horseshoe bat facts

A bat flying towards a branch

Arlington is home to one of the largest colonies of lesser horseshoe bats in Devon, and as such is of international importance. The colony can range from 90-150 bats at any one time. Read on for some fantastic facts about the bats who roost in our historic house.

You can spy on our bat colony (currently closed)

In the cellars at Arlington we have a camera in the attics spying on the bat roost. Most of the year it shows a live feed, but when the bats have flown from the roost, we show a recording of them. There is also a sound wheel where you can listen to the different species of bat and the noises they make.

All the bats in our summer roost are female

It is common for female lesser horseshoe bats to congregate together, especially around the time they give birth. We suspect our roost is made up of new (or soon to be) mothers alongside other female bats who haven’t mated. Father’s take no part in caring for the babies.

Bats can eat up to 3000 midges per night

A common pipistrelle bat can eat around 3,000 tiny bugs each night including midges, which is the equivalent of one third of its body weight. For an adult human this is the same as eating around 137 sandwiches or 24kg of food each day.
During cold or wet summers, when there aren’t many bugs to feed on, bats can go into a semi-hibernating state known as ‘torpor’. This means they expend less energy and can conserve their resources until the weather warms up.

Bats as food

Cats, sparrow hawks, owls and other animals are known to prey on bats. They survive detection by waiting until nightfall to feed.
Around dusk you may see a few exiting their roost site for test flights, to see whether is it dark enough. Once satisfied, they will leave the roost and fly low along hedge rows, tree lines and even garden borders to keep in the shadows. It has been proven that some bats are often reluctant to cross open spaces until it is completely dark, so removing any of their guidelines can prevent them getting enough food, as there are far fewer insects later in the night than at dusk.

Our Red Devon cattle help provide food for the bat

Grazing Red Devon cattle and Jacob sheep leave the grass longer, allowing more wild flowers to grow which encourages more food for bats. They also produce dung, which attracts dung beetles which lay their eggs in the dung. When they hatch the offspring then become food for bats.
The cattle often congregate along hedgerows and field margins as these areas provide shelter from the sun, wind and rain. By creating dung in these areas the Lesser Horseshoe bats can benefit from the dung beetle larvae without having to fly across the open parkland. In August when young bats are first flying, we carefully consider where the cattle should be grazing to give the most food for the bats.

Female bats can choose when they get pregnant

Bats mate from September to November. The females store the sperm within their bodies throughout their winter hibernation. When spring comes (or the female bats feel the conditions are right) they ovulate and the egg is fertilised. Gestation takes between 8 – 12 weeks, depending on the species, and the babies are born in the summer.
Female bats will usually produce just one baby each year. The babies suckle milk from their mothers, but will remain in the roost with the other female adults while their mother goes out to feed. Baby bats are weaned at between 4 – 6 weeks and by 8 – 10 weeks old are fully independent.

Our estate is managed in a bat friendly way

When proposing any changes to the landscape at Arlington we always consider the possible impact on bat flight lines and look to do succession planting to replace any trees which are dying off. Bats often have more than one roosting site for different times of the year. On the Arlington estate there are lots of old buildings and barns which provide a secondary home for the Lesser Horseshoe bats. Nearby there are also suitable old mines and small caves, which the bats can populate.