Country Matters: It was in the bathroom, twiddling its ears

What do you do if, sauntering back from a bath stark naked, you meet a bat coming the other way down the passage? No doubt books of etiquette furnish a correct response, but I was so surprised that I simply carried on, and the bat, with perfect decorum and aeronautical control, shot silently over my left shoulder.

The question then arose of how to evict the creature from the house - for my wife is not keen on having bats indoors, believing that they carry fleas and are hell-bent on seeking refuge in her hair. Clearly my best course was to open the window of the bathroom (which is at one end of the corridor), drive the bat in there, cut off its retreat, and leave it to depart into the night.

By switching some lights off and others on, I flushed it from one of the bedrooms, and after a couple more near shaves in the passage, trapped it in the bathroom, whereupon I doused the light and closed the door. Half an hour later, I found it hanging from the ceiling, with its ears - at the bottom - twiddling furiously back and forth. At the next check, however, it had gone.

The incident tied in with a minor mystery which has been puzzling me in the farmyard. In an old stable that we use as a gym I keep finding the weight-lifting bench littered with moths' wings. I sweep them off every evening, but next day there are more.

I had suspected that this was the work of a bat or bats, and the episode in the bathroom prompted me to consult our local expert. Roger Ransome, a semi-retired schoolmaster, has studied bats all his life, and his expertise is matched only by his unquenchable enthusiasm for garnering more knowledge.

When I mentioned the twiddling of the ears, he immediately told me that my visitor must have been a horseshoe bat, and that what it was doing was getting a fix on me by beaming Doppler-shift echoes. To determine the exact species, he asked, 'Teaspoon- sized or dessert-spoon?' - and when I replied, 'Definitely dessert', he said, 'Greater horseshoe, then.'

He further assured me that horseshoe bats do not carry fleas, and that although other species are infested with them, the parasites are specific to their hosts, and cannot transfer to humans. 'Besides,' he added, 'bats never get tangled in people's hair.'

His information about feeding habits made sense of the detritus in my gym.

Greater horseshoe bats hunt by cruising through the air or hanging from a perch, scanning for prey on the move, and nipping out to intercept victims.

Having caught something, they return to a feeding-post and there dismember large insects, chopping off wings and legs, and shelling carapaces.

Clearly my weight-bench, or one of the rafters above it, has become a feeding-post. But where have the bats come from, and where will they go to hibernate in the winter?

Dr Ransome believes they may well be an offshoot of the colony in a huge, empty Victorian country house three miles away across country. Having studied the greater horseshoes there for years, he knows that the population plummeted from 180 to barely 100 after a bad spring and early summer: the females became very aggressive and chased young males out, pursuing them up and down the bare stone passages, perhaps to regulate the population to the level of food supplies.

As for hibernating, it seems likely that our bats will push off to Minchinhampton, a few miles farther away, and shack up in the disused stone mines there. With the nights growing colder, they may depart any day now, especially as they have grown fat on the bounty of a fine Indian summer.

In my ignorance I imagined that once bats hang up their boots, so to speak, they do so for the duration. Not at all: they deliberately choose caves and mine-shafts through which gentle draughts percolate, so that the air currents bring them news of changes in outside temperature, and they arise from their torpor every few days to drink or feed. Even on this gentle routine they lose about a third of their body- weight during the winter.

It will be a change not to have to dust off my bench every time I go to lift weights. But the nuisance is so small, and so heavily outweighed by the pleasure of playing host to complex and self-effacing visitors, that I very much hope they will return in the spring. If a human being could twiddle his ears like that, he would bring any capital city to a standstill.