Monday, December 22, 2008

Can animals predict the weather? How can animals predict the weather?

Can your dog or a passing flock of birds predict an incoming storm? Is there any scientific research to substantiate those claims? And even more interestingly, if animals can predict the weather, do we stop watching the weatherman and start observing the behaviors of animals at the zoo or in our own backyards?

Storm Image Gallery

an albatross
Tui De Roy/Minden Pictures/Getty Images
Birds, like the albatross, can be greatly affected by changes in the weather. So can they predict when the next storm will hit?
See more pictures of storms.

The implications of such a revelation would surely have a huge impact on people's day-to-day lives. Even more so, these predictions would be especially valuable during catastrophic events like earthquakes, tidal waves, or a one-in-a-million natural disaster, like the tsunami that smashed into Southeast Asia on Dec. 26, 2004.

One of the things we will examine is a widely observed (though scientifically unproven) phenomenon -- even though the tidal wave killed more than 200,000 people, almost no wild animals perished (with the exception of caged or confined animals within the wave's path). Observers report that the animals seemed to have some warning, whether by several hours or just seconds, that allowed them, and the people who heeded those warnings, the chance to find safety.

Can a look say it all?

Most claims of animals predicting weather relate to behavioral changes. However, some animals' appearances cause people to wonder if they might be looking at a living, breathing Doppler radar system.

One of these creatures is the banded woolly bear caterpillar. Some people believe this furry insect, which blossoms into a tiger moth in spring, can predict the severity of the coming winter. According to folklore, if the caterpillar's center brown stripe is long, winter won't be too harsh. If the two black stripes running on either side are longer than the center stripe, batten down the hatches.

So does this caterpillar have an inborn ability to gauge the strength of upcoming seasons? Not at all. A scientist who studied these creatures for years eventually scrapped his entire research project. He found one group of woolly bear caterpillars living near a second group of woolly bear caterpillars. The physical appearances of the two groups completely contradicted each other, thus discrediting their predictive look [source: Rozell].

Do animals have built-in weather detectors?

If your dog always comes inside right before it rains, you may think that animals can predict the weather. It's probably more accurate to say that animals react to certain environmental signals that accompany weather changes, not to the weather itself.

A prevalent opinion is that animals can detect certain events, like earthquakes, as soon as they happen, even if the originating event is a great distance away. While this ability wouldn't make much of a difference to people at the scene of the disaster, it could conceivably assist those located farther from the epicenter. A few researchers even believe animals may be able to sense the precursors to these events before they actually strike. However, hard evidence of this is extremely limited; most of the evidence is anecdotal.

Sadat, the elephant
Charles Pertwee/Getty Images
Some elephants seemed to sense the December 2004 tsunami was coming. This elephant named Sadat helped in the clean-up efforts by clearing debris in Banda Aceh, Indonesia.

Another detail worth noting is that the majority of researchers do not claim animals have ESP or a sixth sense. What they are saying is that animals make greater use of their existing five senses, especially when compared to humans. Let's take a look at how those five senses can operate differently from ours in certain animals.

The most critical sense is hearing. There are some sounds people can't hear. On the low end of the scale are infrasonics, low-pitched sound vibrations on the hertz frequency scale falling below 20 hertz (Hz). On the other end are high-pitched sounds, like dog whistles, which humans also can't hear. People typically hear in a range between 20 and 20,000 Hz (middle-aged adults usually don't hear beyond 12,000 or 14,000 Hz). Elephants, however, generally hear between 16 and 12,000 Hz. Cattle also start hearing sound at 16 Hz, but can continue to hear all the way to 40,000 Hz. And what sort of elements produce sounds in the infrasonic range? The answer includes earthquake shockwaves and ocean waves. See where this is going?

Some researchers think certain animals, like elephants, get an early earthquake warning because they can sense shockwaves in the ground through their large feet. They don't hear the sound and think, "Oh no, an earthquake is coming." But they do sense distant, unfamiliar vibrations rolling in that terrify them into fleeing for safety.

How animals, not just elephants, sense these vibrations is generally unknown. Researchers are examining different organs, body parts and nerve chains in a variety of species that may be able to pick up sound vibrations that humans just can't sense.

This theory could also account for the just-in-time-reactions of other animals with less acute hearing just prior to the tsunami. Researchers note that infrasonic sound produces uneasiness and nausea in people. Animals may perceive these sound vibrations as dangerous and instinctively seek safety.

So what about less extreme causes? Can birds let you know when a storm is coming? Can the behavior of bears alert you to the severity or duration of cold winter months ahead?

Will animal behavior become my weather forecast?

What happens to animals before storms roll in or at the onset of winter? Infrasonic sounds could still be the culprit because hurricanes and thunder produce sound waves at those frequencies. But there's also the matter of changes in barometric (air) and hydrostatic (water) pressure.

Normally, these pressures fluctuate slightly. Animals are highly tuned in to any changes beyond those natural fluctuations, which can signal big changes in the weather. These variations can trigger an animal's survival mechanism. The animals' instinctive reaction is to seek shelter in the face of potentially violent weather.

For example, abnormal conditions like hurricanes cause large decreases in air pressure and water pressure (at least in the more shallow depths). Animals exposed and accustomed to certain patterns can quickly sense these changes. And again, similar to the observed behavior of the animals during the tsunami, they flee for safety.

a seagull over the water
Craig van der Lende/Photographer's Choice/Getty Images
Seagulls are sensitive to barometric changes. It's thought that they return to land if they feel pressure drop.

Researchers observed this type of behavior among a group of sharks as they tracked the sharks' movements during Tropical Storm Gabrielle and Hurricane Charlie. After the barometric pressure dropped just a few millibars -- an occurrence that causes a similar change in hydrostatic pressure -- several sharks swam to deeper waters, where there was more protection from the storm [source: Vatalaro].

Birds and bees also appear to sense this drop in barometric pressure and will instinctively seek the cover of their nests or hives. Birds also use their ability to sense air pressure to determine when it's safe to migrate.

And what about long-term predictions, like how harsh winter will be? It seems that groundhogs aren't holding any cards. Hibernation appears to be related to an animal's biological clock and stored-up fat rather than any ability to gauge temperature trends.

There have been interesting proposals about the validity of some animal folklore. Some Native Americans believe black bears choose different sleeping spots in their caves depending on how cold the winter will be, or the fur on a hare's feet will grow fluffier if heavy snows approach. While there's a chance these are simply coincidences, some have pointed out that science is based on observation, and folklore is based on centuries of observation -- although the observations haven't been conducted in controlled circumstances.

In the end, these animal behaviors may not prove all that useful to humans. Animals frequently exhibit behavior changes, and there's no practical way of deciphering whether a change in behavior is related to an impending natural disaster or just a reaction to something completely unrelated.

Also, differences exist between species -- and between individuals of the same species -- in their sensitivity to weather fluctuations. While some animals may be great weather predictors, others within that same species might not get their spidey senses tingling.

But, if you ever find yourself in a forest reminiscent of the stampede scene in "Bambi," you still might want to follow the crowd and tag along at top speed.

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