Calendar An icon of a desk calendar. Cancel An icon of a circle with a diagonal line across. Caret An icon of a block arrow pointing to the right. Email An icon of a paper envelope. Facebook An icon of the Facebook "f" mark. Google An icon of the Google "G" mark. Linked In An icon of the Linked In "in" mark. Logout An icon representing logout. Profile An icon that resembles human head and shoulders. Telephone An icon of a traditional telephone receiver. Tick An icon of a tick mark. Is Public An icon of a human eye and eyelashes. Is Not Public An icon of a human eye and eyelashes with a diagonal line through it. Pause Icon A two-lined pause icon for stopping interactions. Quote Mark A opening quote mark. Quote Mark A closing quote mark. Arrow An icon of an arrow. Folder An icon of a paper folder. Breaking An icon of an exclamation mark on a circular background. Camera An icon of a digital camera. Caret An icon of a caret arrow. Clock An icon of a clock face. Close An icon of the an X shape. Close Icon An icon used to represent where to interact to collapse or dismiss a component Comment An icon of a speech bubble. Comments An icon of a speech bubble, denoting user comments. Comments An icon of a speech bubble, denoting user comments. Ellipsis An icon of 3 horizontal dots. Envelope An icon of a paper envelope. Facebook An icon of a facebook f logo. Camera An icon of a digital camera. Home An icon of a house. Instagram An icon of the Instagram logo. LinkedIn An icon of the LinkedIn logo. Magnifying Glass An icon of a magnifying glass. Search Icon A magnifying glass icon that is used to represent the function of searching. Menu An icon of 3 horizontal lines. Hamburger Menu Icon An icon used to represent a collapsed menu. Next An icon of an arrow pointing to the right. Notice An explanation mark centred inside a circle. Previous An icon of an arrow pointing to the left. Rating An icon of a star. Tag An icon of a tag. Twitter An icon of the Twitter logo. Video Camera An icon of a video camera shape. Speech Bubble Icon A icon displaying a speech bubble WhatsApp An icon of the WhatsApp logo. Information An icon of an information logo. Plus A mathematical 'plus' symbol. Duration An icon indicating Time. Success Tick An icon of a green tick. Success Tick Timeout An icon of a greyed out success tick. Loading Spinner An icon of a loading spinner. Facebook Messenger An icon of the facebook messenger app logo. Facebook An icon of a facebook f logo. Facebook Messenger An icon of the Twitter app logo. LinkedIn An icon of the LinkedIn logo. WhatsApp Messenger An icon of the Whatsapp messenger app logo. Email An icon of an mail envelope. Copy link A decentered black square over a white square.

Nature Watch: The enigma of bats

Lesser horseshoe bat (Rhinolophus hipposideros) in flight, bat threatened with extinction in Germany. Picture by Shutterstock
Lesser horseshoe bat (Rhinolophus hipposideros) in flight, bat threatened with extinction in Germany. Picture by Shutterstock

Dusk by my local river – and bats should be beginning to stir by an old bridge, but the only movement are trout rising to snap up mayflies that brush the water’s surface.

I wait a bit longer, and then, only inches above the trout-rippled water a bat flickers and swerves.

Another one appears, and then another, and within a matter of seconds the river is alive with tumbling bats.

The mayflies are now under sustained attack from trout and bats in an insect feast in the gloaming.

I turn on my electronic bat detector, and the earphones fill with a marvellous mix of rapid-fire staccato clicks from their echolocation calls.

Ingenious device

The bat detector is an ingenious hand-held device that picks up the ultrasonic calls of bats as they hawk for insects and converts them into sounds that can be heard readily by the human ear.

The detector also provides information on the frequency range of the calls, which is an important means for identifying species when on the wing.

These calls were coming in at just below 50 kHz, which combined with their behaviour of swooping low over the water, made me deduce they were Daubenton’s bats.

This river-loving species is habitually late in leaving their daytime roosts compared to some other types, which further confirmed my identification.

Bats are enigmas, the only mammals that fly and their nocturnal habits further add to their mystique.

18th century fascination

Gilbert White, the pioneering 18th century English nature diarist, was fascinated by bats, and wrote of knowing two species – the pipistrelle and the long-eared bat.

In his seminal book, The Natural History of Selborne, he recounted about being much entertained by a tame bat, which would take flies out of a person’s hand.

“The adroitness it showed in shearing off the wings of flies, which were always rejected were worthy of observation and pleased me much.

“Insects seemed to be most acceptable though it did not refuse raw flesh when offered: so that the notion that bats go down chimneys and gnaw men’s bacon seems no improbable story.”

Flying bat hunting in forest. The Greater horseshoe bat (Rhinolophus ferrumequinum) occurs in Europe, Northern Africa, Central Asia and Eastern Asia. It is the largest of the horseshoe bats in Europe

I suspect house mice were the culprits of bacon gnawing at the time, for bats don’t often enter houses, and bacon would be the last thing on a bat’s mind should one inadvertently tumble down a chimney.

The following day, I ventured out with my bat detector once more, this time to a small burn that runs through woodland behind my house.

The detector buzzed into action – clicks that were peaking at 55 kHz.

These are soprano pipistrelles, which also having a liking for areas by water.

It was only as recently as the 1980s that it became clear that the widespread pipistrelles in Britain comprised of two species, rather than one.

This made me ponder: if we are still finding new mammal species in Britain in modern times, how many other species of mammal are still to be discovered in other parts of the world? And how many will become extinct before we are even aware of their existence?

Conversation