Why not humans? When an imminent disaster so unimaginably primal as this occurs, can only creatures in tune with nature at its most elemental sense it coming?
Research shows that many fish are sensitive to low-frequency vibrations and detect tremors long before humans. The bullhead catfish detects magnitude-2 earthquakes so weak people can't feel them at the top of 10-story buildings, says John Caprio, a biological sciences professor at Louisiana State University specializing in fish senses.
An elephant clears a path in Banda Aceh. Sensitive to ground vibrations, elephants may have detected the undersea quake long before the tsunami hit.
(Beawiharta -- Reuters)
Other animals are also extremely sensitive to ground vibrations. Lynette Hart, professor of animal behavior at the University of California-Davis, says that's what probably cued the elephants, which most likely felt the quake in their feet and trunks. Elephants, she says, are known to "lay their trunks on the ground when an airplane or truck generates large seismic noise," as if to feel it.
With the elephant's intelligence -- its brain is the largest of terrestrial creatures -- "they can figure out what direction the stimulus is coming from, how strong it is, and what evasive action to take," Hart says.
Some animals may have heard the tsunami coming from the moment the quake erupted under the ocean. Species of birds, dogs, elephants, tigers and other animals can detect "infrasound" -- frequencies in the range of 1-3 hertz, compared with humans' 100-200-hertz range, says psychobiologist James Walker, director of the Sensory Research Institute at Florida State University. "It's sensitivity to such a low frequency range that most people wouldn't call it sound anymore."
"The Naked Ape" author and animal behavioralist Desmond Morris says cats and dogs are sensitive to sudden electromagnetic changes -- like those that precede an earthquake -- which is why "many dogs shiver and become scared when a thunderstorm is approaching."
"Canines' sense of smell is 10,000 to 100,000 times superior to that of humans," says Walker, who is starting research to train dogs to detect bladder and prostate cancer in human urine. Dogs' olfactory senses are so sensitive -- they're said to be able to smell fear -- that it's possible they could pick up on chemical changes in the air before an earthquake.
This week, scientists of the Anthropological Survey of India told the Herald Sun of Melbourne, Australia, that members of the ancient tribes it visited on the Andaman and Nicobar islands near the earthquake's epicenter may have been spared because they noticed unusual behavioral changes in the birds, dolphins and lizards.
Chinese researchers have pioneered studies of animals to see how their sensory organs react to minute changes. Their impetus was the earthquake in 1975 that struck the densely populated town of Haicheng in northeast China. Based largely on sightings of unusual animal behavior, the public was warned and thousands of lives were saved. "A lot of snakes came out of hibernation, and they had a week's notice," says Pararas-Carayannis.
Research in China is focused on pigeons, which have shown high sensitivity to ground vibrations in their tibia and fibula nerves, he says. The Chinese are trying to create instruments that replicate such sensitive physiology.
There's evidence not all animals pick up on disasters, cautions Ben Hart, Lynette Hart's husband and a UC-Davis professor of animal physiology. His studies have shown that domestic animals' pre-quake behavior is inconsistent. "It is only a few earthquakes that are preceded by unusual behavior," he says. "Most are not, and we don't have the slightest idea why."
Ruth Buskirk, a senior lecturer in biological sciences at the University of Texas at Austin, says one reason may be "background noise" -- the clutter of sensory stimuli before quakes.
In 1981, Buskirk reviewed the unusual behavior of eels, frogs, snakes, turtles, sea birds, pigeons, chickens, dogs, cats, horses, cows, deer, rats and mice before 36 earthquakes on four continents. She crunched the data every which way. "Our main conclusion was, boy, the animals can sense anything, including very minor changes that happen before earthquakes, but there's so much background noise during an earthquake" that it's unclear what stimuli the animals are reacting to.
University of Maryland animal behavioralist Ray Stricklin says the reported low wildlife death toll in the tsunami areas may have more to do with chance than cognition. "It is quite possible that animals do have the capacity to sense vibrations more than we humans do, but I don't think it is necessary to attribute to them an ability to recognize there is an earthquake or tsunami threatening and know which way to run."
Bart Houx, an ethologist at Utrecht University in the Netherlands, prefers other explanations than "sensory warning systems" for the low animal casualties -- the swimming abilities of certain animals or small animal carcasses being hard to find in the debris. "I would only be convinced that wild animals had higher survival rates if there are relatively few casualties found in wild coastal territories," he says. "But often these places are very hard to tread, and now, understandably, most people have other things on their mind."
Reacting to Pressure
In the 12 hours before Hurricane Charley battered Florida's Gulf Coast last year, 14 electronically tagged blacktip sharks off Sarasota bolted into deeper waters. They stayed away for up to two weeks, then returned. None of them had left its home otherwise in four years of monitoring, according to scientists at Mote Marine Laboratory in Sarasota.
The sharks did the same thing three years earlier when Tropical Storm Gabrielle hit.
"I think these animals are more attuned to their environment than we give them credit for," says Michelle Heupel, a staff scientist. "When things change, they may not understand why it's happening, but the change itself may trigger some instinct to move to an area that is safer for them."
Heupel says what coincided with the sharks' abrupt flight was a big drop in barometric pressure. "Not that they thought, 'Oh my God, the pressure's changing and we've got to go,' " she says. "We know so little about how animals sense these things. These findings are just a glimpse into what animals are doing when we're not looking."