How Animals Forecast The Weather

Growing up in the arid Southwest, I became interested in weather forecasting at a very young age. Rainfall, or the lack thereof, had a lot to do with our quality of life living on a small cattle ranch/farm. I had always heard the older generation talk about "rain signs" or changes in the behavior of animals that meant that a change in the weather was coming. Here are some of the common rain signs and the science behind why they may indeed predict the coming of rainfall.

The Rain Crow

A rain sign that has been noted by farmers and ranchers in the Southwest for many years is the call of the "rain crow". The "rain crow" is another name for the yellow billed cuckoo, as seen in the photo below. The reason that the call of the rain crow may be a rain sign, is that it has a habit of becoming very vocal on unusually hot days. In coastal areas in the summertime, where heat causes moisture to rise off the ocean, a very hot day will often precede a thunderstorm. The call of the rain crow sounds like "ka ka ka ka, cow, cow, cow". These birds are now a threatened species, and the call of the rain crow is seldom heard anymore except in some isolated, rural areas.

Desert Tortoises or "Land Turtles" Crossing The Road May Indicate That Rain Is Coming

The desert tortoise, such as the one seen in the photo above, is not fond of water, nor is it very good swimmer. Scientists believe that tortoises can sense changes in barometric pressure through the pressure exerted on their bony shells. Falling barometric pressure is a strong indicator that a low pressure system is moving in, meaning increased chances for rain. Millions of years of evolution have programmed the desert tortoise to see these changes in pressure as a sign to move to higher ground. Seeing a desert tortoise crossing the road in rural areas of Texas, New Mexico, Arizona and other states, may mean that heavy rains are on the way.

Cows Lying Down May Mean Rain Is Coming

Bovines, including cattle, oxen and bison, have large, multi - chambered stomachs which produce methane gas as they digest grass. Cattle are believed to feel small changes in barometric pressure as the gas in those chambers expands or contracts. Often cattle will be observed lying down, just before a rain, possibly because of the discomfort this pressure change causes. This rain sign may not be as accurate as others though, since cattle are often simply resting after grazing.

Birds Flying Close To The Ground Is A Sign Of Changing Weather

If you notice birds such as vultures, herons, ducks, and other species that normally fly at considerable heights suddenly flying closer to the ground, this may be a rain sign. When weather is disturbed in the upper atmosphere, birds will avoid high winds and fly closer to the ground.

More Of Nature's Rain Signs

You may have noticed that before a change in the weather you tend to see more insects, such as ants and houseflies, in your home. Insects can sense changes in barometric pressure through their bony exoskeletons in the same way that tortoises can. Instinct directs them to seek shelter inside your home before a storm. Insects that can sense changes in weather include ants, scorpions, wasps, flies and spiders.

Aside from sensing barometric pressure it is well known that many species of animals can hear low-frequency sound waves over long distances. Studies have shown that whales can hear low frequency sounds, below 500 Hz, across entire oceans. Perhaps some of the animals responsible for so called "rain signs" can actually hear thunder emanating from faraway storms and sense when they are nearing.

I personally find nature's "rain signs" to be a fascinating phenomenon, even in this age of Doppler radar and satellite imagery. Keeping folklore such as this alive helps keep us humans stay more connected to our natural world. Nature is always offering us subtle clues about what is happening in the environment around us, all we have to do is look and listen.