"Qu'en disent les grenouilles?", they used to whisper at Versailles during that period of uncertainty in 1789 that followed the fall of the Bastille. The query - "What do the frogs say?" - had nothing to do with natural history: it was just that the citizens of Paris were often known as "frogs" because the animals featured on their coat of arms, and the mood of the Parisians was seen as a good barometer of the feelings of the country as a whole in those troubled, revolutionary times.
But "Qu'en disent les grenouilles?" has its place in meteorology, too, since les grenouilles, apparently, have some skill at weather forecasting.
"When loudly croak the tenants of the lake", it was said, you may be sure that rain is imminent. And some species of frog, it seems, also become darker in colour:
The frog has changed his yellow vest
And in a russet coat is dressed.
Some foreign frogs, on the other hand, have more exotic talents. The Rana wittei, or mountain frog, is to be found wallowing in the marshes of the Ethiopian highlands, and croaking on Mount Kenya's northern slopes.
Apparently this frog will continue to croak as long as the temperature remains above 0 C (zero degrees Celsius), but it falls suddenly silent the instant the temperature drops below the freezing point.
But there are practical ways of harnessing the prognostic ability of frogs. In olden times the countryfolk would place one of these unfortunate creatures in a jar half full of water, which also contained a branch of a tree that the frog could use as a kind of ladder to climb out of the water when it had the inclination.
A frog thus equipped, according to the experts, can anticipate changes in the weather. When conditions are bad, and the frog expects them to remain so, it stays in the water and croaks; but as soon as it senses any improvement it edges its way slowly up its ladder. And if a period of fine, bright, sunny weather is on the way, our amphibian friend is invariably to be found at the very top of its domain.
Those who need a long-range weather forecast should focus on the reproductive behaviour of the frog. When they spawn in the middle of a pond it is a sign of an impending drought. But earlier this year, keen observers would surely have noted that the frogs had spawned at the edges of their ponds; when they can be seen by this behaviour to have no fear whatever of a water shortage, it is a sure portent of a very wet summer on the way.