In 1974 bears in Alaska came out of hibernation about two weeks early. They roused themselves from their winter sleep, left their dens, and took to the hills. Soon afterward, Alaska was hit by the worst earthquake in its history.
In 1975 farm animals near Oroville, California, started to act strangely. Chickens refused to enter their coops. Cattle stopped grazing and bellowed loudly in the fields. Horses ran wildly around their corrals. Dogs whined and howled all over the area. This went on for several days. Then Oroville was struck by a major earthquake that measured 6.0 on the Richter scale.
In 1976 people in the Friuli region of northern Italy reported similar events. Here, chickens refused to roost. Cattle panicked in their barns. Hundreds of cats moved out of the area. Mice and rats left their hiding places and marched through people's houses. Once again, this strange behavior was followed by an earthquake.
These stories were reported in the press and were investigated by scientists. Similar reports in recent years have come from China, Japan, Russia, and Guatemala. Experts agree that animals often do act strangely weeks, days, or hours before earthquakes. The animals seem to sense that a quake is coming....
As yet, we do not fully understand the changes that take place in the earth and atmosphere before an earthquake. And we know little about the ability of animals to detect such changes. What is it that the animals are sensing?
For the most part, animals possess the same senses as humans - they see, hear, feel, smell, and taste. In many cases, however, an animal's senses are much more highly developed than ours. A dog identifies odors that our noses can never appreciate. A bat hears sounds beyond our range of hearing. An owl sees on the darkest night. A pigeon feels vibrations that we cannot feel.
Some animals possess senses that are beyond human experience. For example, scientists recently discovered that some animals detect slight changes in the earth's magnetic field. This is an important finding, since magnetic changes appear to be associated with earthquakes.
During the 1960s, scientists at Northwestern University in Illinois found that creatures as different as protozoans, flatworms, and mud snails can be led off course if a magnet is placed in their line of travel. During the 1970s, German scientists demonstrated that honeybees are sensitive to weak magnetic fields. When the magnetic field inside a hive was artificially changed, the bees seemed to lose their sense of direction.
At Cornell University in New York, researchers found that slight shifts in magnetic fields also affect homing pigeons. When tiny magnets were attached to the pigeon's backs, they had trouble finding their way home. When the magnets were removed, the birds regained their sense of direction.
In 1978 scientists discovered small amounts of magnetite in the bodies of honeybees and pigeons. Magnetite is an iron oxide that has magnetic properties. This mineral may make it possible for animals like pigeons and bees to tune in to the earth's magnetic field.
Other recent experiments have shown that several kinds of birds, and some fishes as well, react to small changes in magnetic fields. Researchers also have found that birds can detect slight changes in air pressure. They can hear extremely low-frequency sounds coming from the earth. Magnetic changes, air-pressure changes, and low-frequency sounds all have been associated with impending earthquakes.
So far, no one can say with certainty that animals detect danger signals in the earth and atmosphere before earthquakes. But the evidence seems to indicate that they do. Which signals are the animals reacting to? How do they tell the difference between harmless changes in the earth and atmosphere and changes that may precede a quake?
If we could answer those questions, then we might be able to predict earthquakes with enough accuracy to save hundreds of thousands of human lives.
Reprinted with the permission of Simon & Schuster Books for Young Readers, from CAN BEARS PREDICT EARTHQUAKES? by RussellFreedman. Copyright © 1982 Russell Freedman.
A. tells about extraordinary events.
B. tells a story about animals.
C. includes surprising descriptions.
D. provides mostly factual information.
A. how earthquakes destroy the environment.
B. unusual animal behavior before earthquakes.
C. different ways animals adapt to earthquakes.
D. how earthquakes affect magnetic fields.
A. fish
B. honeybees
C. birds
D. bears
A. to demonstrate that the author can answer them in the last paragraph
B. to summarize the information in the preceding paragraphs
C. to give the reader more information about the animals
D. to show that there is much left to learn about the subject
A. predict
B. react to
C. sense
D. understand
A. an almanac
B. an encyclopedia
C. a dictionary
D. a thesaurus