A Bit About Bats!
The Bat Conservation Trust is the best source of information about UK bat species and for advice regarding bats in buildings, tree maintenance and building work:
UK Bats hibernate through the winter, lowering their body temperature and metabolic rate to survive on their fat reserves. They might start to emerge from hibernation as early as March but will become fully active by April or May. Their mating season is in autumn before hibernation so in May the females gather in colonies within a suitable ‘maternity roost’ where each gives birth to a single ‘pup’. The pup is fed on milk until it is old enough to start catching insects at about 6 weeks old. All UK bat species feed exclusively on insects which makes them valuable for pest control. A tiny pipistrelle can eat up to 3000 insects a night!
Bats are the only true flying (rather than gliding) mammals in the world and form a unique group, the Chiroptera (meaning hand wing). This name is apt because the bones which support the wing membrane are simply extended 'fingers'. While the front limbs are adapted for flying, the small hind limbs are used for gripping when roosting upside down.
Contrary to the saying, bats are not blind and have reasonable vision, but for hunting at night they rely on their superpower of echolocation to pinpoint the position of their insect prey and capture it in mid-flight. They are incredibly acrobatic fliers. Echolocation allows bats to ‘see’ with sound. They emit very rapid high frequency calls, mostly beyond the range of human hearing, and detect the way these sounds bounce off objects to build up a picture of their surroundings. Each species emits a slightly different call and this can be used to identify the species using a ‘bat detector’ sound recording device.
Bats make up more than a quarter of all mammal species in the UK with 18 species (17 breeding) in total. Sadly bat populations have declined considerably over the last century with threats including building and development work that affects roosts, loss and fragmentation of habitat and a reduction in insects. All bats and their roosts are protected under UK law. There are eight species known to be present and breeding in the North East: the Whiskered Bat, Common Pipistrelle, Soprano Pipistrelle, Brandt’s Bat, Natterer’s Bat, Daubenton’s Bat, Noctule Bat and Brown Long-eared Bat.
Bats at Heddon-on-the-Wall
On 7th May 2025 Sustainable Heddon arranged a ‘bat walk’ led by Nic Faulks of the Bat Conservation Trust.
It was a clear dry evening, if a little chilly, and we had an excellent turn-out of over 30 people. We started our event at Heddon Library where Nic gave a fascinating and entertaining talk. We learnt that bats can live for up to 15 years which is amazing when similar-sized mammals like mice and voles only live 2-3 years. For this reason scientists are studying bat genes for research into human ageing.
Nic explained a bit about the different species. Our smallest bats the pipistrelles are adaptable generalists and are therefore widespread and doing quite well. However, many of the more specialist species are struggling as they are more sensitive to changes to the environment such as street lighting. British bat species feed exclusively on insects so the decline in insects is also likely to be affecting them. All bats are protected under UK law.
Each species calls at a different frequency and this may be driven by an ‘arms race’ with their prey. As the insects evolve to detect the bat’s calls, the bats change the frequency to stay a step ahead. Nic explained that we can encourage bats into our gardens by making them rich in insects with areas of longer grass, water features, and insect-friendly flowers. It can also be helpful to put up bat boxes, ideally facing different aspects for the bats to use at different times.
As dusk fell Nic handed out bat detectors which translate the calls of bats to a lower frequency which can be heard by the human ear. This allows us to ‘eavesdrop’ on the bat’s calls and hear what they sound like. We also had a couple of detectors which use the frequency of the bat’s calls to identify the species. From the library we headed down Chare bank and didn’t have to wait long to hear our first bats as we passed the churchyard. Several more bats were heard and seen at the Welfare Field and throughout Heddon Common woods.
Unsurprisingly, common and soprano pipistrelles were the bats we most frequently identified. In a clearing on Heddon Common we had a particularly good display of circling pipistrelles. We also recorded a few noctule bats throughout the night in several locations. The noctule is one of the largest British bats, with long narrow wings. They are primarily a woodland species, living in holes in trees. They are less common than the pipistrelles but still quite widespread, though we are towards the northern edge of their range as they are much less common in Scotland.
Everyone seemed to enjoy the evening and it was great to see so much interest in bats and to learn that we have several different species thriving around our village.
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