Q: How does a tornado explain the finding of a single species in some falls of frogs? Surely, the aerodynamics of the lift might sort for weight but not for species and genus.

—L. Coleman

A: For millennia, people have reported a rare and strange phenomenon: a sudden rain of frogs—or fish or worms—from the sky. You may be minding your own business walking in a park on a blustery day when a small frog hits you on the top of your head. As you peer down at the stunned animal, another one comes down, and then another and another all around you, in a surreal rain of frogs in various states of trauma.

The most likely explanation for how small frogs get up into the sky in the first place is meteorological: a whirlwind, tornado, or other natural phenomenon. Mystery-mongering curiosity collector Charles Fort admitted that this is a possibility but offered several reasons he doubted that’s the true or complete explanation in his 1919 The Book of the Damned:

It is so easy to say that small frogs that have fallen from the sky had been scooped up by a whirlwind … but [this explanation offers] no regard for mud, debris from the bottom of a pond, floating vegetation, loose things from the shores—but a precise picking out of the frogs only. … Also, a pond going up would be quite as interesting as frogs coming down. Whirlwinds we read of over and over—but where and what whirlwind? It seems to me that anybody who had lost a pond would be heard from.

Of course frogs and fish do not live in the sky, nor do they suddenly and mysteriously appear there; in fact, they share a common habitat: ponds and streams. It’s certain that they gained altitude in a natural, not supernatural, way. That there are very few eyewitness accounts of frogs and fish being sucked up into the sky during a tornado, whirlwind, or storm is hardly mysterious. Anytime winds are powerful enough to suck up fish, frogs, leaves, dirt, and detritus, they are powerful enough to be of concern to potential eyewitnesses. In other words, people who would be close enough to a whirlwind or tornado to see the fearful flying amphibians would be too concerned for their own safety to pay much attention to whether or not some frogs are among the stuff being picked up and flown around at high speeds. These storms are loud, windy, chaotic, and hardly ideal for accurate eyewitness reporting.

The same applies to Fort’s apparent surprise that, following frog falls, farmers or others don’t come forward to identify the specific pond the frogs came from. How would anyone know, and why would they care? Whirlwinds and tornadoes may move quickly and over many miles, destroying and lifting myriad debris in its wake. Unless a farmer took an inventory of all the little frogs in a pond both before and after a storm, there’s no way anyone would know exactly where the frogs came from. Neither would it be noteworthy.

Which brings me to the question above: How does a tornado explain finding a single species in some frog falls? The first thing to note, of course, is that before we try to explain something we should be sure that there is indeed something to explain. In this case the writer has asserted, without any supporting evidence or documentation, that some falls of frogs contain only “a single species.” If that is not true—if it is a mistake, for example, or mere rumor or legend—then we need not spend considerable time trying to explain how that could happen.

But the claim does not seem unreasonable, and I’m perfectly willing to concede that it’s possible that in at least a few frog falls only one species of frog was found. Of course, I’d like to know who did the investigation (a herpetologist? a farmer? a little boy who said he only saw one kind of frog?) and what the methods were (How big an area did the person survey to determine how many species of frogs were found? A few feet? A few yards? A mile? If it were a forested or urban area, did he or she search treetops and rooftops for smaller frogs that might have been trapped up there and not made it to the ground, or did the person only count the frogs nearby?). As long as we’re looking at this from a scientific perspective, I’d also be curious about how the determination of single-species frog dispensing was made. Different species of frogs may look alike, have similar colors, or be unidentifiable because of injury from falling from a great height; did the person reporting the data have the frogs collected, catalogued, and identified by a biologist to conclusively determine that only one species fell?

I would argue that the evidence for single-species frog falls—however plausible—is far from definitive because of a dearth of information about how the data was collected. Rumors and third-hand information are routinely cited in the Fortean literature as self-evident truth and established fact.

These questions aside, the most likely answer is that the ponds and rivers that were the source of the frogs had only one species in them to begin with. Unless we know that the waters over which those tornados and whirlwinds travel have multiple species of frogs in them, there doesn’t seem to be much mystery to the fact that only one species may sometimes be found picked up in them. It’s entirely plausible that a whirlwind or tornado (especially one confined to a localized area of a few miles) might cross over only one river, stream, or lake during its time and pick up only one species of frog.

The comment that “the aerodynamics of the lift might sort for weight, but not for species and genus” is a non sequitur, because weight is a function of genus and species. Some species of frogs (just like some species of any animal) are larger and heavier than other species. I am not an expert on frogs and do not claim to be, but it seems that the statement would be valid only if all genus and species of frogs in a given location had equal mass and weight and were therefore equally likely to be picked up by a passing whirlwind or tornado, all else being equal. Frog falls are weird and rare but hardly unexplainable, and neither is the fact—if indeed it is a fact—that they may affect a single species. And that’s a falling frog fact.