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6 Nisan 5759 - March 24, 1999 | Mordecai Plaut, director Published Weekly
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Opinion & Comment
Sylvia Curruca Proclaims "There Is A Borei Olom"
by Joshua Josephson

Part II

Part I of this article looked at some wonders of animal migration and briefly examined the implications of these facts for the theory of evolution. This part continues with an examination of some marvels of animal navigation.

Tristan da Cunha is a group of six small islands named after the largest and northernmost one of the group. The islands lie in the South Atlantic almost four thousand miles south of the equator, and over two thousand miles away from each of the three surrounding continents -- Africa, South American and Antarctica.

The southernmost island of the group, Nightingale, which has an area of less than 38 square miles, lies about 20 miles southwest of Tristan da Cunha. Its coastal cliffs are the nesting site of a sea bird whose common name is the greater shearwater.

These birds feed during the summer months in the North Atlantic, from Newfoundland to Scandinavia. They set out in the autumn from their various feeding areas and fly between 7000 and 8000 miles over featureless ocean to nest on Nightingale.

Though only a tiny dot of land afloat in millions of square miles of virtually empty ocean, several million shearwater somehow find their way to it, unerringly, every single year.

How they manage to converge on this small piece of land is as yet a mystery. This ability appears to be so incredible that one author was prompted to refer to it as a "miracle of navigation."

But as difficult as this capability may seem, it pales in comparison to what some other animals can do. Birds that fly high can at least detect an island from a reasonably great distance. The scope of vision of turtles, however, is surely far less. Nevertheless, turtles too somehow manage to home onto a tiny bit of land awash in the open seas.

Ascension Island lies a few thousand miles north of Nightingale, slightly more than 500 miles south of the equator, midway between Africa and South America and about 1400 miles from the nearest Brazilian coast. There is no other land in between. Not more than about seven miles at its widest point with a total area of 34 square miles, the island was difficult for humans to find before the invention of modern navigational aids. Its highest point is Green Mountain (2,817 feet) and is visible from sea level only when one gets to within a few miles of the island.

The island is mainly inhospitable to life, with no surface streams and little indigenous vegetation. But it is to the sandy beaches of this tiny island that the globally endangered green sea turtles, who can lift their heads but a few inches above the water, gravitate to nest between the months of January and April.

Green turtles that have been tagged on the island have been recovered on the coast of Brazil, 1,400 miles away. And these turtles come back to Ascension Island year after year. Five turtles tagged in one breeding season returned to the island in a later breeding season, four to the same beach.

How do animals do it? How can they navigate across open ocean to find a pinpoint of land more than a thousand miles, or even thousands of miles, away? How does a turtle keep its bearing despite inclement weather, wind, waves, and ocean currents? No one really knows.

But for the past half century, ever since these sorts of abilities of animals were formally recognized by the scientific community, scientists have been trying to discover the methods with which animals orient, navigate, home and migrate. And what they have discovered is nothing less than astounding.

They have discovered, naturally, that many animals are endowed with senses and abilities that we humans clearly lack. Some of these abilities had indeed hitherto not even been suspected.

For example, they have found that animals can hear sounds we cannot, can smell odors we cannot, and can see parts of the spectrum or things like the polarization of light that we have no inkling about from our unaided senses. And despite its seeming impossibility, animals can even detect, and meaningfully use, the earth's magnetic and electrical fields.

Virtually all animals studied have been found to possess an extremely accurate biological clock that tells the animal the precise time of day. Some species regulate their activity by lunar phase -- i.e. they know precisely what part of the month it is. And many species, such as migratory birds, even possess an accurate annual clock. They instinctively can tell precisely what season it is even though they are placed in total isolation and in uniform conditions with no clue about the world outside.

Many animals use the sun as a compass to accurately tell direction and are not at all fooled by the sun's movement across the sky. They compensate accurately for its movement even when they are placed indoors with no clue as to the whereabouts of the sun.

At least one species (the beach amphipod) has been found which can navigate using the moon. Doing this is extremely complex, much more complicated than using the sun for such a purpose. The sun at least moves in a fairly regular way across the sky from day to day. Its position in the sky hardly varies from one day to the next.

The moon, however, has a very different pattern of movement. Because the earth rotates on its axis, the moon appears to move across the night sky during the course of every night. But the moon also moves on its own accord. It travels in a circle around the earth. The direction of this motion is opposite to the motion caused by the earth's revolution.

In effect, at any particular time of night, it is not in the same location as it was on a previous night or as it will be on a subsequent night. From day to day its position changes by about 12 degrees, or about one 15th of the visible sky.

The animal which uses the moon to navigate also happens to use the sun for the same purpose during the daytime. This implies that it possesses a dual tracking system for finding its way around.

Then there is navigation by stars. So far only birds that migrate by night have been found to possess this capability.

This is why sylvia curruca is so special. It is one of the few species that possesses this ability and was one of the first species with this ability to be studied carefully. (In fact, the experiments were conducted with several species of related birds, all sylviids. For sake of simplicity, however, I will lump these results together as if the experiments were done on a single species.) What was found is truly amazing.

To be sure, the experiments with the sylviids were done before certain facts about navigational abilities in general were discovered and before some techniques for studying such things were fully developed. So there exist some criticisms, or at least questions, about the original findings. Nevertheless, the original experiments still stand and have never actually been refuted. They are consistently reported in recent books on animal and bird migration.

Let's look at the details of these birds' abilities. If true, these facts present an incredible spectacle of the natural world. And even if not completely true, even if the facts are only those that critics are willing to accept, they are more than sufficiently awesome to warrant careful attention.

Sylvia curruca's common name is the lesser whitethroat. It is a warbler (a type of songbird) that lives in northern Europe during spring and summer and migrates to sub-Saharan Africa during the autumn. It is a nocturnal migrant, flying only at night.

It was noticed that these birds were somehow using the stars to orient themselves for migratory flight. To test precisely how, some birds were taken into a planetarium and shown different views of the night sky. When shown the autumn night sky as it would appear in their home locale during migratory season, these birds aligned themselves and attempted to fly in the direction of their migratory route.

This was true even when the stars on the planetarium ceiling were rotated in such a way that what appeared to be south was really north. When they were shown only diffuse weak light, however, the birds aligned themselves only randomly. Both these facts showed that the birds were using the configuration of the stars for finding direction, not some other cue, such as the earth's magnetism.

To get to Africa, the birds generally fly southeast from northern Europe, passing over Bulgaria and Turkey. When they come to the area of Cyprus, they turn due south, cut across the Mediterranean and head straight up the Nile valley. They then disperse over a fairly large area of mid-Africa.

As they fly south from northern Europe, the positions of the stars are constantly changing. So the experimenters wanted to see what would happen if these birds were taken on an imaginary migratory flight.

Guess what? As they changed the star map the birds changed course. When shown the constellations as they would appear over the northern parts of the their trip, their alignment direction was generally southeast. But when the configuration of the stars appeared as it would over Cyprus, the birds changed direction and headed due south, just as they would in real life. Then when they were shown the sky as it appears over their final destination, they became totally disinterested in migratory behavior. They thought they were at the end of their migratory flight and settled down to rest.

More interesting, these birds were able to find their way to their destination even when they were taken on an imaginary flight to a locale which they had never experienced. When shown an image of a night sky over Lake Balkash in Siberia, several thousand miles to the east of where they would normally be and a place to which they had never been, they turned due west to get back to where they belonged.

The image was then changed gradually to give the appearance of actual flight to the west. As soon as the stellar configuration gave the birds the appearance of being over Romania, the birds changed course, and began heading south, the direction they must take to get to the Nile valley.

Show these birds a totally unrealistic sky, however, and they get totally confused. They face in all different directions. Since this type of configuration never happens in reality, they have no way of knowing where they are.

The abilities displayed by these birds are uncanny. For these birds to use the stars as they do, they must (a) have a very accurate map of at least some of the stars and know accurately the position of these stars at each time of year and day; and (b) have a fantastically accurate internal clock that tells them both day of year and time of day.

But there were more surprises in store for the experimenters. Birds that had been reared in isolation from other birds, reared in sealed areas and with only very limited exposure to the night sky, or none at all, were taken into the planetarium and shown the night sky as it appears over their home territory in the autumn at the time they ought to be migrating. After only a few moments of hesitation, these young, inexperienced birds, faced in the direction they ought to face to begin their migration to Africa, a land they had never seen, using a system of navigation they had never used and information that could not have been known to them before.

The conclusion is inescapable. These birds are born with some knowledge of the features of the night sky etched into their brains. Precisely what comprises this information is one of the subjects of controversy. But the essential conclusion has been corroborated from later experiments on a number of other bird species which migrate at night. At least several different kinds of birds instinctively use information provided by the stars to determine migratory routes.

Different mechanisms, however, seem to be used by different species. The sylviids may be an exception rather than the rule.

The experiments with inexperienced sylviids were done under a stationary planetarium sky. The fact that the sylviids were able to orient under such a condition meant that they could tell direction merely by looking at the configuration of the stars, at the geometric shapes formed by the bright and less bright stars. This in turn implies that they must be born with preexisting knowledge about star patterns, a proposition with which scientists are extremely uncomfortable (for good reason, no doubt).

Experiments with other species, however, have found that other species at least use a somewhat less spectacular method for identifying direction. One species, the indigo bunting, seems to know where south lies not by looking for star configurations in a stationary sky, but by looking at the way in which the sky rotates. The stars in the north make small semicircles during the night, while the stars in the south make very large semicircles in an equal amount of time.

It is assumed that the buntings discern north by observing the area of the sky which has the least rotation. They instinctively know that their direction of migration in the fall is opposite the direction of this least rotation, of course making adjustments as necessary for the precise angle of flight.

But even the slightly less amazing ability of the indigo bunting implies that these birds' genes "know" (believers in evolution have to say "stumbled by chance on") much about the world around them. They know that there is day and night, that at night there are points of light in the sky, that these points of light move, that these points of light move differently in different regions of the sky, and that it is possible to determine direction by observing how these points of light move. And after all this is discerned, the genes instruct the bird which way to fly.

In essence, no matter what is involved, it must be concluded that some birds are born with a genetic program that matches the reality of the world in a very precise way.

The implications of all of this for evolution is easy to understand, especially in light of the arguments made in part I of this article. Several features of these particular facts make the argument against evolution very compelling. To do justice to these arguments however, requires a whole other article, which, G-d willing, is forthcoming.

For now though, a single quote from an article by an expert in the field, who strongly believes in evolution, should suffice to make the point.

The article, by Kenneth P. Able written in '80, reviews three decades' worth of findings and studies regarding animals' abilities to orient, navigate and home. The author generally attempts to minimize the wonder of it all by arguing that animals are really not using incredibly sophisticated or complex mechanisms to find their way. Whenever possible he posits an alternative mechanism, such as a refined sense of smell or sound, that would make navigation and homing a less unbelievable feat.

But the author encounters a slight difficulty with which he cannot contend. During the late '70's, scientists tracking the migration route of the monarch butterfly discovered that large numbers of these butterflies spend winters in Mexico in a small patch of mountainous forest surrounded by miles and miles of forest which all looks alike.

This is all Able has to say about this amazing phenomenon:

"The recent discovery in Mexico of very localized winter roosts inhabited by staggering numbers of monarch butterflies . . . leads one to wonder how the butterflies find these isolated, but traditionally used, sites at the end of a flight that may well exceed 2500 km. . . . [There is no reason to think that any individuals return to the winter roost a second time. The monarch butterfly lives a short period of time. The butterflies that head back to Mexico in the fall are all the children, grandchildren or even great- grandchildren of those who left to go north in the spring.] For the autumn migration of these butterflies to be goal- directed in the absence of any opportunity for learning requires a seemingly impossible level of complexity for genetic engineering. Similar problems surround the first autumn migrations of young birds, discussed below [this discussion includes the abilities of the sylviids]."

Need more be said?

Although Able is not willing to admit it (the most he can get himself to say is "seemingly impossible"), this is about as strong a concession as one can expect from a believer in evolution. I have yet to encounter one that is stronger.

But that's his hang up.

We, however, who know the existence of a Borei Olom from our historical experience, should have no difficulty recognizing the facts for what they are. And we can certainly be proud and aggressive in broadcasting these facts to all who will listen. Birds and butterflies loudly proclaim: "We are creatures of an awesome Creator and not the products of chance."


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