some people believe these events are caused by tornadoes that occur over bodies of water. The theory is that the tornadoes, whose force sucks up animals into the clouds, are also responsible for carrying the animals until they are dropped back onto land. However , this explanation has never been proven. It also does not explain why many of these rainfalls consist of only one species, and why many of them consist of species that are not native to the area where they fall, but to an area many hundreds of miles away.