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By Sophie Costain, DEFA Ecosystems Policy Officer

With colder days upon us and we start to get cosy in our homes; turning on radiators and enjoying the extra roof insulation we installed over the summer, the Island’s bats are also settling down, and finding places for long ‘naps’ and periods of hibernation to get them through winter when it’s harder to find flying insects outside (food). 

The Isle of Man has 9 different species of bat, which often roost in close proximity to humans. A bat roost is any space that they use for shelter and protection, including where they hibernate in the cold winter months, or breed and bring up their babies in summer (yes, some species of bat actually have maternity roosts where the mothers and babies live together, well away from the fathers!). Many species return to the same roost site year after year. It’s worth noting that bats and their roosts are legally protected from harm and disturbance under the Wildlife Act 1990, so we actually have a legal responsibility to keep them safe.

Bat roosts can be in hollow trees, caves (obviously!) but also in spaces around our homes and other buildings. Bats are opportunistic, taking advantage of small nooks and crannies such as in-between stonework, under tiles, guttering, lead flashing or sometimes our nice warm attic spaces. Beneath their furry coats they are tiny, and can squeeze into really small spaces, some can fit in holes the size of your thumb. But overall they make pretty good tenants, as they are generally not loud or rowdy, they don’t chew through cables or other materials around your house, and like to keep to themselves so people can live with them for years and be unaware.

They also provide important ‘services’ around our houses, such as keeping insect populations down; a single pipistrelle bat can eat up to 3000 midges and mosquitoes in one night!

Bats are mostly nocturnal (active at night), though a few are also crepuscular (active at dawn and dusk) – so when you’re next enjoying your outdoor barbeque, keep an eye out at dusk for the bats that are helping to keep the midges off you! They are fantastic flyers, and never get caught in your hair or nightdress – they can ‘see’ with sound, and you can often hear (or feel) their high-pitched squeaks when its quiet.

Apart from the general declines in insect populations due to habitat loss and climate change, other challenges that bats are facing are also climate-change induced - but this time unwittingly by our efforts to be more energy efficient.

While we all need to do our bit to lower our carbon emissions, unfortunately bats and roosts can be at risk from some home energy efficiency measures – making properties air tight, installation of loft and cavity wall insulation, can deprive the bats of their roosting nooks and crannies or disturb them during key parts of the year. Maternity roosts are particularly vulnerable as the young won’t be flying yet, and so it’s a complicated business to coordinate flying, feeding and sleeping for a giant crèche!  

Of course, having bats doesn’t mean that alterations can’t take place, and with a bit of forethought, advice from DEFA, and yes possibly a bit of a change to your work plans and schedule, buildings can be made more energy efficient whilst retaining places for bat roosts. You can even put bat boxes or bricks up around your property, to encourage bats, even if you don’t yet have them.  So, you can do your bit for the planet and your local wildlife at the same time. WIN WIN for everyone.

So what do you need to do to help protect bats?

Take a few minutes to look outside your house just after dusk, and see if there are active bats. (That doesn’t mean they’re living in your house, but will give you an idea if they are in the area)

Always make thorough checks (around and inside your property) before implementing measures that could harm bats or roosts – remember they are legally protected.

If you know, or suspect, you have bats and want to make changes around your home, get advice from the DEFA Ecosystem Policy Team on 01624 651577 or

If you find a bat in your property call the Ecosystem Policy Team or the Manx Bat Group helpline on 07624 366177.


  • Ecosystems
  • Bats
  • Wildlife
  • Home Energy