Friends of Abbey Fields Bat Walk 2021 was held on 07 July 2021 and attended by 26 people. The walk was held on an overcast, damp, and quite humid evening. Starting at 21:15, it was led by Dr Jon Russ of Ridgeway Ecology, and he was assisted by John and Julia Waller, all three of whom are members of Warwickshire Bat Group.
Jon provided much information about bats, the only truly flying mammals.
Among the largest bats in the world are the group commonly called Flying Foxes. These live in areas such as Southeast Asia and Australia. These bats can weigh up to 1.6 kg with a wingspan of up to 1.5 m. Generally, they eat fruit and flowers, but occasionally they eat insects.
At the other end of the scale are Kitti’s hog-nosed bats, also known as Bumblebee bats. This is a near-threatened species found in western Thailand and southeast Myanmar. It is the smallest species of bat and arguably the world’s smallest mammal. These bats typically weigh 2g with a wingspan of 17 cm. Generally, they eat insects.
There are about 1250 species around the world, but in the UK, we have about 18 species.
Bats feed on Insects, invertebrates, fruit, nectar, other bats, birds….and blood. However, ‘vampire bats’ live in the rainforests of America, and their preferred prey are large birds, horses, cows and pigs. They do not kill their prey but just take small quantities of blood. (We will not be subject to Dracula-like attacks in Kenilworth!)
In the UK, all bats feed on insects. The smallest bat is the Pipistrelle, and the largest is the Noctule. Pipistrelles will eat between 2,000 and 3,00 midges per night!
Noctule Bat (photo Dennis Atherton)
In Abbey Fields, we will likely see Common Pipistrelle bats, Soprano Pipistrelle bats, Noctule bats, Brown Long-eared bats and Daubenton’s bats. They like to roost in crevices in buildings, trees, roof spaces, bat boxes and other similar spaces. Different species have different preferences, as well as different preferences for the numbers who roost together. More details can be found on the Warwickshire Bat Groups web pages.
Jon provided us with Bat Detectors, and we could listen to the bats detecting and catching insects as well as some of the ‘calls’ between bats whilst in flight. Bats communicate or detect using sound frequencies ranging from 15 – 125 kHz. Without bat detectors, we would not be able to hear the bats – the detectors convert their sounds to frequencies which we can hear between 20Hz and 20kHz. Whilst the detectors provide the sounds as clicks or brief chirps at various individual frequencies, the actual sounds that bats make can be likened to birdsong, with a range of frequencies emitted very quickly.
In the evening, not only were we able to listen to the bats, but we also saw them flying quite low, among the trees (Common and Soprano Pipistrelles) near The Barn and a little later low over the water of the lake (Daubentons, Pipistrelles and Noctules). Despite the weather, we saw and heard a lot of bat activity.
Jon provided us with a lot of other information, including the following:
In the UK, all bats hibernate. Some bats migrate from Estonia to the UK in winter and return to Estonia for summer – quite a journey with a big sea crossing!
- Bat females only have 1 pup per year
- Bats do not generally carry diseases harmful to humans
- Bats are predated upon by owls, hawks, cats and even Great Tits (if they are very hungry)
- There are bats which can catch birds
- There are bats which can catch fish
- Bats generally live between 10 – 20 years, but 1 individual was recorded as living over 40 years!
This was a very interesting and informative Bat walk.