Bats and their ways with the barometer

It is easy for a meteorologist to become discouraged by the limitations of his natural abilities

It is easy for a meteorologist to become discouraged by the limitations of his natural abilities. Many people, maybe knowing one or two, will wisely nod their heads and say they can easily understand why this might be. Those of a literary bent might quote the Bard:

Condemn the fault and not the actor of it and then, sotto voce, add in a little Byron for good measure:

The fault was Nature's fault, not thine,

Which made thee fickle as thou art.

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But you misunderstand. I am not comparing weather-people to normal human beings, but to other animals who have skills that meteorologists can only envy.

It is a well-known fact, for example, in circles that believe such things, that pigs can see the wind, a talent, needless to say, that would be of inestimable value to meteorologists. Grasshoppers, too, can tell how warm it is exactly, and broadcast their reports in the form of a chirp whose frequency is related to the temperature. And the ability of porpoises which live in Kerry to predict the weather for months ahead is widely known. But now, it seems, a bat has a barometer.

It has long puzzled scientists that certain species of bat seem to have an uncanny knack of knowing precisely when the air outside their caves is rich in insects, and when, therefore, it is worth their while to emerge and take a meal. On nights when very few insects are abroad, most bats, it seems, stay comfortably at home and snooze. But how do they know, without coming out to take a look?

The suggested answer is that bats are sensitive to atmospheric pressure. The clue comes from the fact that deep within the caverns where many of them go home to roost, the meteorological environment is remarkably stable: temperature and humidity stay virtually static for weeks on end, and there are no air currents - but the barometric pressure varies with the pressure in the outside world.

Sure enough, research has revealed that in the regions concerned the number of insects on the wing decreases when the pressure is high, and increases when the barometric pressure falls. Moreover, when bats were allowed to roost in a special chamber in which the barometric pressure could be controlled, respiratory rates and other metabolic indicators varied with the pressure setting, suggesting that the animals were in some way sensitive to this kind of change.

The precise nature of the bat-barometer is, as yet, unknown, but scientists suspect it may be the "vitali organ", a structure of the middle ear that is found only in bats and birds - but not, alas, in meteorologists.