Batmanship in Beaulieu

There is a colony of tiny pipistrelle bats in our barn. In the summer evenings, the swallows who spend summer in the abandoned house circle and swoop, catching insects on the wing. Then suddenly they all retire, there is a brief pause, and the bats come out like the Changing of the Guard at Buckingham Palace, also to consume insects. The swallows of course migrate at the end of summer, to South Africa we are told, while the common pipistrelles hibernate in the barn, dramatically reducing their heartbeats and metabolic functions to consume virtually no energy during the winter months. When my daughter was eight, she came into my room one morning saying “Daddy, there’s something black on the stairs”. A baby bat, fast asleep. Wearing gloves, I picked it up and we studied it closely – still asleep – before putting it on the woodpile in the barn. Then just a couple of weeks ago, Geraldine’s daughter Ombeline was having dinner when a bat which had got in through an upstairs window made it down to the kitchen and circled her head a couple of times before fleeing through the open kitchen door.
Having decided to find out more concerning our nocturnal tenants, we went to Beaulieu-les-Loches to meet up with Vincent and Virginie, two bat experts from the Groupe Chiroptères d’Indre-et-Loire, an association for the study and protection of bats in the region. Vincent talked us through the amazing facts and figures about these creatures, the only flying mammals in the world. They have the ability to couple and then defer gestation, because the female stores the sperm as long as she wants, ensuring that her baby (they only have one offspring at a time) is born in Spring when food is available. They fly at between 25 and 70 kph and, when feeding, eat up to half their weight in insects – though a pipistrelle weighs no more than a 50-centime coin. They are not blind, despite the proverb, but have eyesight that is more or less as good as ours – though of course they navigate at high speed using echolocation, emitting sharp high-pitched blips from the larynx or – in the case of some species – the nose. When they catch an insect in their mouths, they can no longer make this noise, so – to avoid collisions – they fly in small circles while eating their prey.
It was curious meeting two people who had such a fondness for these eldritch life forms. Bats are a protected species. Vincent and Virginie have an SOS line to save bats in peril, and they told us about a colleague who saved the lives of baby bats by popping them into her bra to keep them warm against her breasts. In common with swallows, their numbers and the locations of the colonies are important ecological and meteorological indicators. There are 34 species in France and 23 in Indre-et-Loire, with the highest concentration being in this region of France and particularly around Loches, with all its old tuffeau quarries, cellars and troglodytic habitations. 
At sunset, we went out into Les Prairies du Roy, a small nature reserve with a gorgeous view of Loches across the river Indre. We glimpsed the bats in flight, following the path of a row of trees or hedges. But Vincent and Virginie went one better. They had “batbox” bat detectors – handheld devices that pick up the bats’ ultrasonic shouts (above 20kHz) and bring them into audible range. It was like radar, hearing the increasing volume of rapid-fire blip-blip-blip calls approaching, glimpsing the speeding bat overhead, then hearing it recede. Each species of bat has a different call, and they are clearly distinguishable. The enthusiasm of Vincent and Virginie for bats is apparently unbridled. Is this a curious rural equivalent of the trainspotters of my London youth?
We continued chatting under a full supermoon. When they heard about my colony, in a locality they had not yet explored or developed a statistical picture for, they immediately set up a visit, during which they plan to capture a bat for a brief get-to-know-you session.
So more news of chiropterans anon…

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