The riddle of migratory birds: Another evidence of God’s design
by Kyu Bong Lee
Even the stork in the sky knows her appointed seasons, and the dove, the swift and the thrust observe the time of their migration. Jeremiah 8:7, NIV
Autumn is almost drawing to an end. Winds from the Arctic are gently blowing south, heralding that winter is not far away. Soon the northern lands will freeze, covered by snow. Suddenly you hear a noise in the sky. You look up, and you see a flock of birds flying southescaping the freezing temperatures and seeking warmer lands. Flocks and streams of birds continue their journey for hundreds of miles. Come spring, the reverse occurs, and the birds fly north to breed and raise their young. The migration is unmistakable, annual, and rhythmicrevealing one of the great wonders of the natural world.
How does one account for such migrations? Why do birds migrate at all? How do they know when its time to begin the long journey? What guides their flight path and direction? How do they know their destination, and how do they prepare for the trip?1
These and other questions have occupied research of scientists for years. Some questions have brought clear answers; others are still being searched out. For a scientist committed to the Christian worldview, the migration of birds is another instance revealing that there is a divine design behind all such wonders of nature.
Dispersion of migratory birds
With birds, migration usually means a two-way journey, an annual round-trip. Mostly, this occurs with birds in the large lands of the Northern Hemisphere that are covered seasonally with winters snow and ice. Flocks of birds living in Eurasia and North America cross the Equator to spend the winter season in Africa or South America.
For example, a tagged arctic tern was picked up 90 days later on the coast of southeast Africa, 9,000 miles (14.481 km) away from its northern home. Another tern flew more than 10,000 miles (16.090 km) from Greenland to reach southeast Africa. Still another, ringed on the Arctic coast of Russia, was retaken off Australia, an impressive distance of at least 14,000 miles (22.526 km).
The white-rumped sandpiper makes the same autumn sea hop from maritime Canada to the tip of the Antarctic. Among land birds, the bobolinks navigate 7,000 miles (11.263 km) or more between the clover fields of Canada and the grasslands of Argentina. The most famous migrant in Europe is the widely beloved white stork. Sometimes they ride the thermals to a great height before gliding the 10 miles over water to Africa.
Some sandpipers have been clocked at more than 100 miles (161 km) per hour. Some birds migrate long distances over water and fly as high as 14,000 feet (4.267 m). The highest altitude recorded thus far is 29,500 feet (8.992 m) for geese near northwest India.
How birds navigate during the migration
Most biologists offer four theories, and suggest that birds use one or a combination of these in their navigation over long distances.
Use of visual landmarks. This has long been a popular theory. Many birds seem to follow visual clues such as rivers, coastlines, and mountain ranges in order to arrive at the correct destination. However, this idea does not explain how birds keep from getting lost during their very first migration.
Use of the Sun. According to this theory, birds, like humans, possess an internal circadian clock that allows them to track the daily light-dark cycle. Along with this internal clock, birds seem to use the Suns shadows to gain a sense of location. Through the use of these two devices, birds would be able to use the Sun as a compass.
Birds traveling by daytime would orient themselves by the position of the Sun. But on cloudy days when the birds cannot see the Sun at all, how are they able to align themselves properly? They have an internal time clock by which they are ruled. Perhaps this can be explained as a result of Gods creation.
Use of the stars. Because many birds migrate at night, these nocturnal migrants appear to have learned to use the stars for navigation. Birds can orient themselves in relation to the North Star, and unlike the Sun-compass, this star-compass is not time dependant. Young birds seem to use this pattern of rotation to distinguish north from south. This theory is supported by an experiment that was conducted with indigo buntings.2
Some birds seem able to use patterns of stars, small clusters of stars, or the Moon to determine what direction they need to fly. A disadvantage of using the stars to navigate is that the North Star cannot be seen in the Southern Hemisphere. Another problem arises on cloudy nights, when the stars cannot be seen.
Use of the Earths magnetic field. Biologists have two different theories on how birds could use the Earths magnetic field to navigate. One is that birds have certain pigments in their eyes that become weakly magnetic when they absorb light and thus alter certain nerve signals that the eyes send to the brain.3 A second, and more popular theory, comes from the fact that scientists have detected tiny crystals of magnetite along the olfactory tract in the brains of some birds.
Biologists still do not know how the birds can sense the position of the magnetite crystals in their heads, and there is little experimental data on the subject. (Interestingly enough, some researchers say that humans have the ability to sense the magnetic field as well.) Two observations are worth noting. First, with reference to homing pigeons:
Careful tests with homing pigeons and other birds displaying the ability to judge direction show that the birds are affected by changing magnetic field. . . . If birds are released at places where the earths magnetic field is anomalously strong, their homing ability is entirely disrupted. . . .
Next to, or essentially in, each pigeon skull, [the researchers] have located a tiny piece of tissue 1 mm by 2 mm (about 1/16 in by 1/8 in) that was somewhat magnetic. Searches inside this tissue with an electron microscope revealed the presence of more than ten million tiny crystals each four times as long as wide. Other tests demonstrated that these crystals were magnetite, the iron-oxygen compound of which compass needles are made.4
Second, a research observation on bird migration from northern Wisconsin to the Amazon:
How birds find their way from a northern Wisconsin pine tree, south to the Amazon and back again is still not completely understood by science. But a half-century of research is shedding some light on this amazing feat.
Birds can track the sun, the moon and the stars, using their apparent movement as a compass. Birds also use other senses. They can detect weak magnetic fields with tiny magnetite crystals in their heads. They follow faint odors as does a salmon returning to its birth river from the ocean. They can see polarized light and use barometric pressure. Along with memory and genetic urges to head in a certain direction, birds use a combination of these senses to cross continents and oceans.5
Recently it was discovered that monarch butterflies
have an internal magnetic compass that enables them to make their winter
journey without the guidance of sunlight.6
As mentioned in the above paragraphs, it was shown that some fishes and
butterflies also use their magnet-detecting senses. (See sidebar, Salmon
Despite all the theories and experiments dealing with bird migration, there is much that is still not understood about how birds determine their position in relation to a fixed goal. The fact is that they continue to migrate on a cyclical and predicable pattern through centuries.
What causes birds to migrate?
What causes birds to migrate? When did the practice of migration begin? Some scientists once suggested that the ice sheets during the Ice Age might have been originally responsible. This idea sounds plausible, but it does not explain migration in many parts of the world that have never been touched by glaciations. Consequently, most ornithologists now reject this theory as a basic cause of migration.
There is no question that the birds that originated in warm climates spread outward in their search for food. Most Creation scientists have held that the Ice Age existed for hundreds of years in some areas after Noahs Flood because of change in weather. After the Flood, many birds found food in abundance in higher latitudes but were forced to withdraw when winter came.
What stimulates birds to begin their migration at approximately the same time each year? What internal clock or external stimuli? From a physiological point of view, we know that the endocrine glandsthe controls that make male birds sing and females lay eggsundergo great changes before the nesting season. Other changes occur after the nesting season is over. Most birds migrate during this period.
While evolutionary scientists may have their views, we as Christian scientists can attribute all these magnetic mysteries to Gods design, the same as we do with many other kinds of animal migration. God made birds to adapt themselves to the change in their surroundings. Because birds need extraordinary stamina to travel long distance, these migrants have the ability to store a vast fuel supply in the form of fat, sometimes doubling their weight. Moreover, the greatest wonder of migration is the manner in which birds find the waytheir navigation skill. Surely, one can see a supernatural design in all these!
Navigation is the part of migration that has puzzled scientists the most. How birds can find their way with apparent ease over vast distances remains the unsolved riddle of migration. So precisely can they follow their invisible paths that scientists have from time to time suspected that birds possess a special sense unknown to us. At one time they were thought to have a kinesthetic sense, by which they could form patterns of their route through pressures on the inner ear. Another idea was that birds navigate through responses to the Earths magnetic field, perhaps even to its rotational effects. None of these hypotheses has, however, stood the test of experiment.
The Bible, however, invites us to study the wonders of nature and to see in them evidences of the handywork of a wise Creator: Ask the animals, and they will teach you, or the birds of the air, and they will tell you. Look at the birds of the air, your heavenly Father feeds them (Job 12:7, 8; Matthew 6:26, NIV).
So, what we can learn by observing or studying bird migration? First, not all birds migrate. Therefore, migration is not the law of all flying birds. Secondly, birds take more or less the same migratory routes. This selection cannot be by chance. Third, before sin, there would have been no migration, for in the pre-Fall world, there would have been no harsh climate necessitating bird migration.
Consider migration itself and its relation to the Earths
magnetic field and gravity. The magnetic field changes according to the
latitude of the Earth and height. The strength of gravity also changes
according to latitudes, though we usually say, gravity is constant.
God created the Earth, populated it with all kinds of creatures, and designed
each of them to be adapted to its circumstances. Also, the Sun radiates
the light and electromagnetic energies to all the creatures. These might
be affected by quantum energy even though they may not feel it. God designed
the birds to make good use of their tiny variation in energy and also
gave them abilities to detect even the smallest amount of gravity and
variations in the magnetic field in ways that are unknown to us, and to
orient themselves toward this direction. To the extent this happens, migration
reveals Gods intelligent design and benevolent providence.
Kyu Bong Lee (D.Sc., Sungjun University) teaches physics in the School of Natural Sciences, at Sahmyook University, Seoul, Korea. E-mail: email@example.com
Notes and references
1. See Peter Berthold, Bird Migration: A General Survey (Oxford University Press, 1993); Peter Berthold, Control of Bird Migration (London: Chapman and Hall, 1996).
2. See www.channelone.com/ns/news/96/12/96/1205/story1.html; How Birds Migrate, About Hummingbirds- users.vnet.net/joecool/hummer.fact.html.
3. Stephen Day, Migration, New Scientist 135 (September 12, 1992).
4. T. Neil Davis, Magnetic Navigation by Birds, Alaska Science Forum, Article #345 (September 28, 1979).
5. Steve Tomasko, Mystery of Bird Migration: How They Get Here from There, in Science Café, Columns (April 4, 2000).
6. Orley Taylor, Jr., Monarchs Migration. E-mail:firstname.lastname@example.org
7. Larry Gedney, Do Salmon Navigate by the Earths Magnetic Field? Alaska Science Forum, Article #691 (November 23, 1984).
8. Ellen G. White, Counsels to Teachers, Parents, and Students (Mountain View, California: Pacific Press Publ. Association, 1913), p. 189.
9. Ellen G. White, Education (Mountain View, California: Pacific Press Publ. Association, 1952), pp. 117, 118.