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?

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.

The belief that animals can predict earthquakes has been around for centuries.

In 373 B.C., historians recorded that animals, including rats, snakes and weasels, deserted the Greek city of Helice in droves just days before a quake devastated the place.

Accounts of similar animal anticipation of earthquakes have surfaced across the centuries since. Catfish moving violently, chickens that stop laying eggs and bees leaving their hive in a panic have been reported. Countless pet owners claimed to have witnessed their cats and dogs acting strangely before the ground shook—barking or whining for no apparent reason, or showing signs of nervousness and restlessness.

But precisely what animals sense, if they feel anything at all, is a mystery. One theory is that wild and domestic creatures feel the Earth vibrate before humans. Other ideas suggest they detect electrical changes in the air or gas released from the Earth.

Earthquakes are a sudden phenomenon. Seismologists have no way of knowing exactly when or where the next one will hit. An estimated 500,000 detectable quakes occur in the world each year. Of those, 100,000 can be felt by humans, and 100 cause damage.

One of the world's most earthquake-prone countries is Japan, where devastation has taken countless lives and caused enormous damage to property. Researchers there have long studied animals in hopes of discovering what they hear or feel before the Earth shakes in order to use that sense as a prediction tool.

American seismologists, on the other hand, are skeptical. Even though there have been documented cases of strange animal behavior prior to earthquakes, the United States Geological Survey, a government agency that provides scientific information about the Earth, says a reproducible connection between a specific behavior and the occurrence of a quake has never been made.

"What we're faced with is a lot of anecdotes," said Andy Michael, a geophysicist at USGS. "Animals react to so many things—being hungry, defending their territories, mating, predators—so it's hard to have a controlled study to get that advanced warning signal."

In the 1970s, a few studies on animal prediction were done by the USGS "but nothing concrete came out of it," said Michael. Since that time the agency has made no further investigations into the theory.

Erratic Behavior in Dogs

Researchers around the world continue to pursue the idea, however. In September 2003 a medical doctor in Japan made headlines with a study that indicated erratic behavior in dogs, such as excessive barking or biting, could be used to forecast quakes.

There have also been examples where authorities have forecast successfully a major earthquake, based in part on the observation of the strange antics of animals. For example, in 1975 Chinese officials ordered the evacuation of Haicheng, a city with one million people, just days before a 7.3-magnitude quake. Only a small portion of the population was hurt or killed. If the city had not been evacuated, it is estimated that the number of fatalities and injuries could have exceeded 150,000.

The Haicheng incident is what gave people hope that earthquakes might be predictable, says Michael, and what prompted the animal behavior studies by the USGS.

It was later discovered, though, that a rare series of small tremors, called foreshocks, occurred before the large quake hit the city.

"It was the foreshock sequence that gave (Chinese officials) the solid prediction," Michael said.

Still, the Chinese have continued to look at animal behavior as an aid to earthquake prediction. They have had several notable successes and also a few false alarms, said Rupert Sheldrake, a biologist and author of the books, Dogs that Know When Their Owners Are Coming Home and The Sense of Being Stared At.

A reproducible connection between animal behavior and earthquakes could be made, he said, but "as the Chinese have discovered, not all earthquakes cause unusual animal behavior while others do. Only through research could we find out why there might be such differences."

Sheldrake did his own study looking at animal reactions before major tremors, including the Northridge, California, quake in 1994, and the Greek and Turkish quakes in 1999.

In all cases, he said, there were reports of peculiar behavior beforehand, including dogs howling in the night mysteriously, caged birds becoming restless, and nervous cats hiding.

Geologists, however, dismiss these kinds of reports, saying it's "the psychological focusing effect," where people remember strange behaviors only after an earthquake or other catastrophe has taken place. If nothing had happened, they contend, people would not have remembered the strange behavior.

Reporting Strange Behavior

Sheldrake disagrees. Comparable patterns of animal behavior prior to earthquakes have been reported independently by people all over the world, he said. "I cannot believe that they could all have made up such similar stories or that they all suffered from tricks of memory."

More research is needed and is long overdue, said Sheldrake, who proposes a special hotline or Web site where people could call or write in if they saw strange behavior in their animals. A computer would then analyze the incoming messages to determine where they originated. A sudden surge of calls or e-mails from a particular region might indicate that a quake was imminent.

The information would be checked to make sure the observations were not caused by other circumstances known to affect the behavior of animals, such as fireworks, or changes in weather. And to avoid issuing false warnings, Sheldrake said, the data would be used in conjunction with other monitoring devices such as seismological measurements.

"Such a project would capture the imagination of millions of people, encourage large-scale public participation and research—and would be fun," he said. "What is holding this research back is not money but dogmatism and narrow-mindedness.

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.

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 hydro static (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.

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 

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.

Animals and Weather: Cheat Sheet

• So far, science hasn't found a surefire way to answer many of the questions we have about animals' behaviors, perceptions and motivations. Until that time, it's hard to prove once and for all what's going on in their heads.
• It's highly unlikely animals can predict weather in an ESP-sort of way, but they very well may be able to sense environmental signals that humans miss. Reaction is another key component: A human might sense a drop in barometric pressure, for example, but not feel compelled by that sensation to seek shelter before a storm hits, as an animal might.
• Another potential reason animals might react to impending weather events and natural disasters differently than humans is because at least some of their five senses almost always surpass our own. Many weather occurrences generate noises in the infrasonic range, too low for people to usually hear, for example, but well within the hearing range of many animal species.
• There are many ways the conditions of an environment may alter to give animals a heads-up that something rough is on the way. Apart from barometric pressure and sound waves, there can also be changes in hydrostatic, or water, pressure.
• How animals pick up on and react to fluctuations in environmental signals likely varies from species to species, as well as among the individuals of those species.