Bat to the bone: Keep your eyes to the sky ahead of International Bat Night
International Bat Night takes place on 24th-25th August 2024
On a clear August day, if you looked to the sky during dusk, perhaps out into your garden,[1] or onto a nearby park, green space, river or even pond, you may have just been able to spot a bat taking flight in the warm summer air, searching for a meal of insects. There are nearly 20 species of bat that can be seen across the UK, accounting for a quarter of all our mammal species.[2] Over half of these bat species have ranges that include the East of England (Bedfordshire, Cambridgeshire, Essex, Hertfordshire, Norfolk, Suffolk), including the UK’s largest bat, the noctule, which can have a wingspan of 40cm; as well as one of the UK’s smallest bats, the common pipistrelle, which can weigh less than a sheet of A4 paper!
All UK bats eat insects, ranging from biting midges, to beetles, to mosquitos to moths; and bats are amazingly able to catch and eat these insects on the wing, through their use of echolocation.[3] In between foraging, bats can be found roosting in caves, trees, bat boxes or even buildings. Bats do not build permanent nests,[4] so if you believe you have bats roosting nearby or in your loft, they will move on eventually. Summer is an important time for bats to develop the necessary fat and nutrient stores for their breeding period in autumn, followed by a long period of hibernation in autumn and winter. [5]Some bats will eat thousands of insects every night through the summer in anticipation of this, as during their hibernation period bats often enter a state of torpor, significantly lowered metabolic activity,[6] resulting in minimal movement and decreased body temperature. In this time, bats will live almost entirely off the fat stores they developed during their foraging period in spring and summer, however, some bats may emerge every so often to hunt on warmer nights during the latter part of the winter.
Of concern this year, there are reports that many bats are exhibiting signs of malnourishment and starvation, which could be linked to a greatly reduced emergence of adult flying insects this summer.[7] There are a number of potential factors affecting the populations of flying insects, and sightings of many of these flying species have already been steady decline,[8] but a particularly wet spring season of heavy rains is thought to be a major contributor this year. The impacts of a reduced adult flying insect emergence[9] this year could have far-reaching ramifications on bat populations as we approach autumn and winter, with many bats that may have not been able to developing the necessary fat stores being less likely to be able to breed and hibernate successfully.[10]
In the UK, bats are highly valued as a key biodiversity indicator species;[11] and tracking their populations, alongside a number of other animals, yields important data on a range of factors affecting the country’s ecosystems, as well as providing us important snapshots of the overall health and resilience of the environments bats live and forage in, which include woodlands,[12] grasslands and urban areas. Thanks to concerted conservation efforts, several of these monitored bat species have actually seen population increases in recent years, which may now be forestalled due to the reduced emergence of adult flying insects this year, and over half of the UK’s bat species are still under threat or endangered, reflecting a considerable population decline in the last century, as well as reduced ranges.
However, providing bat boxes for bats gives them safer options to rest and roost in urban, and wild, areas, as bats can be at risk from attacks by cats and foxes if resting in exposed or low spaces.[13] A consideration of bats and of where bat boxes can be a part of our villages, towns and cities could just make the difference in giving bats a better chance to develop the necessary nutrient and fat stores to mate and hibernate successfully, especially where there may otherwise be few or poor potential roosting sites. Bat boxes can help bats maintain their current population ranges, particularly in areas of urban expansion and new building development.[14]
Groundwork East champions a number of ongoing projects that includes conservation work including installing bat boxes, such as our Green Recovery Project, in partnership with Huntingdon District Council.[15] Groundwork East staff also learned more about bat boxes, including how to construct them from scratch,[16] during a recent staff day.
References:-
[1] https://www.woodlandtrust.org.uk/blog/2020/05/bats-in-gardens/
[2] https://www.bats.org.uk/about-bats/what-are-bats/uk-bats
[3] https://www.bats.org.uk/about-bats/flight-food-and-echolocation-
[4] https://www.bats.org.uk/about-bats/where-do-bats-live/bat-roosts/what-is-a-roost
[5] https://www.bats.org.uk/about-bats/a-year-in-the-life-of-a-bat
[6] https://www.woodlandtrust.org.uk/blog/2018/12/do-bats-hibernate-in-winter-and-more-bat-facts/
[7] https://www.theguardian.com/environment/article/2024/jul/21/where-are-all-the-bats-alarm-as-numbers-fall-in-england
[8] https://www.nature.com/articles/s41467-019-08974-9
[9] https://www.rhs.org.uk/wildlife/pollinators-decline-in-numbers
[10] https://www.theguardian.com/environment/article/2024/jul/21/where-are-all-the-bats-alarm-as-numbers-fall-in-england
[11] https://www.bats.org.uk/about-bats/why-bats-matter
[12] https://forestrycommission.blog.gov.uk/2024/05/22/the-importance-of-woodland-and-trees-to-uk-bats/
[13] https://www.bats.org.uk/about-bats/threats-to-bats
[14] https://www.bats.org.uk/our-work/buildings-planning-and-development/bat-boxes
[15] https://www.groundwork.org.uk/east/what-we-do/green-recovery/
[16] https://www.wildlifetrusts.org/actions/how-build-bat-box