By Hayley Care (Care Ecology) on behalf of SLH
Bats are nocturnal flying mammals and make up almost a quarter of our mammal species in the UK.
We have 18 species of bat in the UK, 17 of which breed here:
- Common pipistrelle
- Soprano pipistrelle
- Nathusius’ pipistrelle
- Brown long-eared bat
- Grey long-eared bat
- Daubenton’s bat
- Natterer’s
- Serotine
- Noctule
- Leisler’s bat
- Whiskered bat
- Alcathoe bat
- Barbastelle
- Bechstein’s bat
- Brandt’s bat
- Lesser horseshoe bat
- Greater horseshoe bat
- Greater mouse-eared bat (vagrant species)
Of these, those in bold are most likely to be found throughout the Heatons.
Our UK bats are much smaller than the large fruit bats that you can see in the bat cave at Chester Zoo. One of our largest UK bats is the Noctule, it has a wingspan that can reach 400mm but can still fit in the palm of your hand. One of our smaller bats, the pipistrelle, is about the size of a thumb and weighs about the same as a 20p piece!
Noctules are one of our biggest bats.
In comparison, a pipistrelle’s body is about the size of a thumb with a wingspan of ~190 mm to 235 mm.
What do bats eat and where do they hunt?
Contrary to the well know saying ‘blind as a bat’, bats are not actually blind. However, being nocturnal they rely heavily on their ears and the use of echolocation to navigate and hunt in the dark. Echolocation is where bats ‘shout’ as they fly and the returning echoes give them information on what is ahead of them. They can even tell the shape and size of an insect and which way it is going.
Their shouts are so high in frequency that they are inaudible to us and we require a bat detector to tune into their call frequencies, converting them into sounds that we can hear.
All of our UK bats eat insects such as midges, moths, flies, spiders, earwigs and beetles which they catch on the wing (while flying) using echolocation. Some species, such as the brown long-eared bat, can also pick insects off of leaves and bark, this is called gleaning. Their large ears are particularly sensitive and allow them to listen to insect movement sounds as well as using echolocation.
A brown long-eared bat’s ears are nearly as long as their body and are very sensitive to sound.
Bats will fly (or ‘commute’) to suitable hunting grounds where there is an abundance of insects to eat, sometimes traveling long distances (Noctule bats are known to fly tens of kilometres from their roost to favoured foraging sites). Waterbodies, woodlands, grassland and farmland are all important feeding habitats for bats, although some species will prefer a particular type of habitat over another. In urban areas, important foraging habitats include parks, allotments, ponds and gardens.
Waterbodies such as ponds, lakes, canals and rivers are great for seeing foraging bats, particularly the Daubenton’s bat which catches insects close to the water’s surface and also the pipistrelle species. (Daubenton’s have even been seen to catch insects from the surface with their feet or scoop them up with their tail membranes).
Ponds and surrounding vegetation provide important foraging habitat for bats.
Commuting habitat
To get to these hunting grounds bats will use linear features such as tree lines, hedgerows, woodland edges and rivers to traverse across the landscape. These features provide protection from predators (such as birds of prey) and also act as navigational landmarks as the bats echolocation calls bounce off vegetation allowing them to travel at night. These connecting habitats are especially important in more urban areas where links to good quality feeding grounds can be sparse. Gardens in particular can provide an important food source and act as habitat connections.
Where do bats live? What is a roost?
When they aren’t flying about foraging for food, bats live in roosts in which they sleep, mate and raise young. Bats do not make roosts but rather will use ‘ready-made’ or existing features that will protect them from the elements and predators. Bats will change roosts throughout the year, switching to different roosts depending on their yearly lifecycle and the temperature.
For example, females gathering in maternity roosts prefer warm roosts in which to give birth and raise their pups. Whereas in the winter when food is scarce and temperatures drop, bats will seek out hibernation roosts which are cool and provide a constant temperature. This is because bats will go into torpor whereby they lower their body temperature and slow their metabolic rate to enable them to use less energy and survive on fat stores. A cool and constant temperature reduces the risk of them waking up from torpor and using up energy at a time when food availability is low.
Most of the UKs bats evolved to roost in trees using features such as cavities, rot holes, hollows, woodpecker holes or even tucked under lifted bark or behind thick, mature ivy. Caves and rock fissures also make good roosting places and are often good hibernation sites.
Man-made structures also provide plenty of opportunity for roosting bats and are not restricted to castle ruins, old barns and spooky mansions! Bats can find roosting opportunities in most structures from modern houses to flat roofed buildings in a business park, to bridges, garden sheds, stable blocks and churches. They will also use purpose made bat boxes.
Not all bats hang upside down from rafters either, as is often portrayed in cartoons and films. In fact, only the greater and lesser horseshoe bats will hang in this way. Certain species will have different requirements and roost characteristics. For example pipistrelle bats are crevice dwelling and will happily squeeze and roost under roofing tiles and roofing felt and behind hanging tiles, soffits and eave boards.
Interesting facts:
- Bats can live for up to 30 years
- Pipistrelles are the most common and widespread of our bat species and the ones that you are most likely to see. A single pipistrelle can consume 3,000 insects in one night!
- Brown long-eared bats’ huge ears are not always obvious despite being nearly the same length as their body. They can tuck them back under their wings or curl them back to look like rams’ horns when they are resting.
- A female will give birth to a single pup which will suckle from it’s mother’s milk for three to four weeks. At four weeks the young are able to fly and at six weeks they are able to forage for themselves.
What is my best chance of seeing a bat?
By looking up! It is amazing what a flurry of activity can be going on unnoticed above your head and also just how much we can actually see in the dark once our eyes adjust. You don’t have to have a bat detector to be able to see bats but having one does help in hearing whether a bat is coming your way and to be able to try to identify what species it is.
Around mid March to April bats become active and having come through the winter months they are hungry and will be out and about foraging for food on most nights. They may also be moving between several roosts before females start to form maternity colonies around May. If we get a cold snap then they are able to slow down their activity levels and may go back into torpor to preserve their energy until warmer weather arrives.
The best time to look is from dusk to about an hour after sunset when bats start leaving their roosts to go out to forage.
If you are lucky enough to have a garden, you can watch for any bats leaving roosts from nearby buildings or trees. They may also be hunting in the garden itself. Take a chair, a blanket and a drink of your choice and set yourself up facing your house, structure or tree, ideally with the sky backlighting it to give you the best chance of seeing flying bats once it gets darker. Also try to block out / face away from any light sources such as exterior lighting or security lighting, as this can really affect your night vision. Then sit and wait to see if any bats appear. The first bats tend to start emerging from their roosts around 20 to 30 minutes after sunset.
By angling your viewpoint to make the best use of the lingering light you are more likely to see the outline of bats against the night sky.
This common pipistrelle was recorded foraging up and down these back gardens in Stockport 25mins after sunset on the 8th April 2020. For the video and to hear the echolocation picked up using the BatBox duet bat detector follow this link.
Another option is to go for an evening walk to try and find foraging bats. The River Mersey is an excellent spot for watching bats hunting for insects over the water and along the tree lined paths. Make sure you have a torch for when it gets dark so you can see where you are going (ideally take a head torch with a red light so as to cause the least disturbance to bats once the light levels drop).
An evening walk along the River Mersey is a great place to spot foraging bats.
If you can’t wait for it to get dark (and particularly at the moment when outside access is limited) the Essex Wildlife Trust have a special bat box webcam which allows you to see into the otherwise secret activity of a soprano pipistrelle roost without having to leave your house!
Local bat groups (such as South Lancashire Bat Group) and nature conservation groups (RSPB, The Wildlife Trust, National Trust) often run guided bat walks throughout the year which you can take part in.
How do you identify bat species using echolocation?
- Bats use echolocation to navigate their surroundings and to hunt for food
- Bat detectors allow us to ‘tune in’ to the frequency that a bat is calling at
- Bat species can be identified from their echolocation frequency and call patterns, along with their appearance and characteristics in flight
- Research is currently being undertaken to allow us to understand other calls that bats make which are termed ‘social calls’. It is thought that it is possible that these calls can be interpreted to understand other bat activity such as a mother bat communicating with her young.
- There are a whole range of different bat detectors which can enable us to listen in to bat echolocation, some can even record sonograms which show bat call patterns and frequencies to help in species identification.
Equipment for listening and identifying bat calls. From left to right: A handheld BatBox Duet bat detector, an Echometer Touch detector that can be plugged into your mobile phone with an app that displays sonograms in real time, a head torch with both white and red light and a key book for identifying bat calls and sonograms.
Bats and the law
All British species of bat and their roosts are protected in Britain by both domestic and international legislation which protects individual bats and their roosts.
As a brief summary, it is illegal to take, injure, or kill a bat in the UK. It is also a criminal offense to damage, destroy or block a bat roost (even if they are not using it at the time). Licences to permit otherwise illegal activities relating to bats and their roost sites can be issued by specific licensing authorities in each country. The BCT website provides further advice on bats and the law and what you can do if you are concerned that works may affect bats or a bat roost. If you are planning works that has the potential to affect bats, you can also get in touch with a professional bat ecological consultant who can advise on how best to proceed.
Threats to bats
Unfortunately, the UK’s bat populations have suffered severe declines during the past century which can be attributed to some of the following:
- Loss and/or fragmentation of foraging and commuting habitat such as hedgerows, woodland and ponds
- Change in farming practices resulting in the loss of habitat and use of pesticides resulting in reduced abundance of insects
- Loss of roosts sites due to development or building works and loss and fragmentation of habitat due to infrastructure schemes such as roads
- Cat attacks are one of the most common causes of bat mortality and injury
- A change in night time lighting levels by artificial lights can impact on bats foraging behaviour and can result in disturbance and the loss of commuting and foraging routes.
- Fly paper in roof spaces can lead to bats getting stuck
A brown long-eared bat’s wing after being caught by a cat. Sadly, this individual was in a bad way and died overnight.
If you find an injured or grounded bat then you can contact the South Lancashire Bat Group Batline on 0161 7648850, or if it is outside of their area, contact the National Bat Helpline 03451300228. They can advise on what to do and arrange for an experienced bat carer to come out to assess the bat.
What can I do to help bats in my area?
As well as being festinating creatures, bats are a key part of our ecosystem and having bats around is a sign of a green and healthy environment.
Luckily there are lots of things that you can do and get involved in to help our bats.
- Gardening for bats means encouraging the insect life – it can include planting flowers and shrubs with night flowering blossoms, scented and/or pale flowers (such as honeysuckle, star jasmine) to encourage insect prey.
- Create a wildlife pond to provide a water source and opportunities for bats and a whole range of wildlife.
- Planting and/or maintaining linear features such as hedgerows, tree lines or shrubbery.
- Let a section of your garden grow a bit wild. Mowing small margins of wild patches can help to make them look more defined and managed.
- Try not to have bright lights illuminating darker edges of the garden at night as some species are particularly sensitive to changes in lighting levels and may be deterred from visiting these areas.
- If you have a cat, try to avoid letting it out at night, and particularly at around dawn or dusk when bats may be leaving and returning to roosts.
- Put up a bat box – there are many different designs and types of artificial bat box that can be installed to provide a roost space. There are a whole range of boxes that can be used in different habitats from ones that you can hang on trees and attach to the outside of a building to ones which can be specially designed to be set within an exterior wall so as not to be seen.
You can even have a go at building your own bat box with these plans and instructions from the RSPB.
- Join a bat monitoring programme to help record where our bats are and to assist in their conservation. The Bat Conservation Trust run a National Bat Monitoring Programme which anyone can take part in, from beginners to experts, so have a look and see if it is something that interest you
- Sending in your sightings and bat records to your Local Recording Groups which can be found via this link. In the Heatons, you can send you records to the South Lancashire Bat Group using their recording form
For more information, see the following BCT leaflet for further detail on how you can encourage bats in your area.
Allowing an area of your garden to become ‘wild’ provides habitat for all kinds of wildlife.
Mowing a short boundary to areas of wilder grassland or meadow can keep a managed look whilst having the benefit of retaining lots of pollinator plants for insects and wildlife.
Examples of different types of bat boxes. From left to right: Schwegler tree boxes, Chillon WoodStone bat box, Vincent Pro bat box that can be mounted on structures or trees (photos from https://www.wildcare.co.uk/wildlife-nest-boxes/bat-boxes.html) and an integrated Habitat box set within an external wall.
Key websites for more information on bats and how to get involved
- Bat Conservation Trust
- South Lancashire Bat Group
- BCT Help I’ve Found a Bat
- South Lancashire Bat Helpline (our local area)
- National Bat Helpline
- How to build you own bat box
- Wildcare website where you can purchase bat detectors and bat boxes
Books on Impact on Insects and Wildlife we make via our gardens:
- The Garden Jungle (or gardening to save the planet) by Dave Goulson (Jonathan Cape)
Excellent Podcast on Echolocation and the evolution and natural history of bats
- BBC podcast from “In our time”. This is well worth the effort if you have 45 mins. It explains their evolution and how difficult it has been to understand their special skill , especially echolocation.
Two baby bats which were taken into care after falling from a roost to which they could not be returned. They did well and were successfully released in the autumn.
Common pipistrelle bat