Be batty about bats
We were lucky to be able to arrange late in the season a bat walk with Rachel Bates from the Cambridgeshire Bat Group. 25 of us visited Rampton on a warm sunny evening on 23 September. Rachel led us on a walk from the village green to All Saints Church, then out across a couple of fields, visiting potential bat habitat like high hedges and veteran trees along the way. Rachel brought along a number of bat detectors which we were able to use, and after a slow start the bats eventually emerged. We heard and identified both common and soprano pipistrelles. Some of the bats were close enough for us to see as dusk fell.
What really made the walk though was Rachel’s enthusiasm and incredible depth of knowledge – she’s a font of fascinating facts about bats and their ecology. There are 18 species of bat present in the UK, with 12 of these previously recorded in Cambridgeshire. All Saints Church at Rampton is unusual in Cambridgeshire as it has a thatched roof. I, in my blissful ignorance, had thought this would be brilliant roosting habitat for bats! But apparently thatch is too tightly packed to allow bats access, and bats prefer old, tiled roofs with lose tiles to shelter under. Small bats, such as the pipistrelles we saw, can even use gaps in stone walls as shelter. Staying at the church, Rachel found some pipistrelle droppings in the church porch. To the untrained eye they look like mouse poo, but if crushed they crumble to a shiny dust. This is because bat droppings are comprised from left over bits of the insects they feast on.
There is much we don’t know about bats lifestyle. Amazingly for such small mammals they can live to be 40 years old or more. In comparison a mouse will live for around 2-4 years. Rachel explained than bat RNA (or do I mean DNA!) doesn’t show signs of aging when studied – so will be identical in a 10 or 40 year old bat. Bats grow old and die, but don’t show the effects of old age. Bats aren’t blind but use echolocation – sonar – to fly in the dark and hunt insects. Some species, such as the brown long-eared bat are involved in an evolutionary arms race with their insect prey. Insects evolved to be able to hear the sonar of an approaching brown long-eared bat and developed strategies to avoid being munched – such as dropping like a stone out of the air to fool the bat. In return, brown long-eared bats evolved to possess incredibly outsized ears, to be able to use sonar more quietly and once again sneak up on unsuspecting insects.
Brown long-eared bat c. Ireland’s Wildlife
Breeding is equally strange. Bats congregate in specific mating roosts from around September or October time, but the females can store sperm and delay becoming pregnant until spring. They then give birth to their pups when the weather is warm and food sources plentiful. Males can get carried away chasing the ladies in breeding season, neglecting to hunt and feed, and ending up in poor condition. This rather reminds me of several of my university friends in their early 20s. It is not unusual for bat group members to find weak out of condition male bats in the breeding season – and to nurse them back to health on a diet of yummy mealworms.
Bat walk season, and bat survey season for professional ecologists, runs in general from May to September or so. Survey work requires plenty of dawn starts and late nights and is very intensive. Volunteers can help – such as by surveying maternity roosts, which are often found in churches. This involves arriving before dusk with deckchairs, blankets, tea and snacks, and counting bats as they emerge from their roosts to get an idea of the numbers present.
We hope Rachel will be able to fit in several more bat walks during summer 2022, and if there is interest locally, it would be great fun to arrange some roost surveys at local churches. To learn a whole lot more about the fascinating bats in the county, take a look at the Cambridgeshire Bat Group online and on Facebook page.
