SI Vault
There Are Problems when Man Plays God
Gilbert Rogin
November 04, 1968
The cahow, a bird that the Spaniards mistook for a devil and the English thought was silly, is a living—barely living—monument to man's effect on his environment. A Bermudian naturalist is attempting to save the cahow from its enemies and itself, while wondering if its fate is not the fate of all of us
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November 04, 1968

There Are Problems When Man Plays God

The cahow, a bird that the Spaniards mistook for a devil and the English thought was silly, is a living—barely living—monument to man's effect on his environment. A Bermudian naturalist is attempting to save the cahow from its enemies and itself, while wondering if its fate is not the fate of all of us

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In the cahow, as well as in other birds, chick mortality is greatest just before or immediately after hatching, a phenomenon that has been reproduced experimentally by feeding sublethal diets of DDT to bobwhites and pheasants. This probably occurs because the DDT residues in the mother are passed into the yolk. When the embryo absorbs the yolk, the DDT enters its system, and the older it gets the more poison it assimilates—thus the highest concentration occurs when the yolk is fully absorbed around the time of hatching.

DDT is a nerve poison. Its presence in the vicinity of a nerve causes hyperactivity, resulting in restlessness and eventually tremors and death. DDT also operates on at least one other mechanism—it can cause the liver to break down sex hormones, including the female sex hormone estrogen, which in birds affects maternal behavior as well as calcium metabolism. When this estrogen breakdown is induced, brooding behavior may be changed, leading to abnormalities such as egg eating. Records kept since the 1890s show that eggshells have had a consistent thickness and weight through the years. However, beginning in the late 1940s and coincidental with the introduction of DDT, many species of carnivorous birds have laid eggs with shells as much as 25% lighter than the norm. These are prone to breakage and loss of water, and apparently contribute to chick mortality.

The only real solution to the DDT problem is discontinuing its use. There are alternative pesticides that are less persistent and just as effective. Better yet is the use of procedures that control only the pest species population. DDT isn't a pesticide—it is a biocide in that it will kill all animal life if present in sufficient quantities. Ironically, the insects for which it is intended can afford the terrific mortality rate since they reproduce rapidly and through natural selection develop resistant strains that require ever-greater dosages to kill.

No one knows how DDT will eventually affect life on earth. The cahow story, when correlated with other evidence, suggests it may be disastrous to carnivorous birds. The mortality of salmon and trout fry from DDT in Lake Michigan and Lake George could soon be repeated in the ocean, if it isn't already happening. Pacific hake, mackerel and tuna have been found to contain 0.2 to 2.0 ppm, higher concentrations than those in fish of many lakes with heavily treated farmland in their watersheds. Organisms at the bottom of the food chain are also susceptible. Thirty-nine percent of a batch of brine shrimp were killed within three weeks by a concentration of one part per trillion—the equivalent of 1/1,000th of a drop in a tank car lot. A few parts per billion in water can decrease photosynthesis in certain phytoplankton. These algae are the indispensable base of marine food chains and are responsible for more than half the world's photosynthesis. Says Wurster: "Interference with this process could have profound worldwide biological implications."

Fortunately mammals are better equipped than other vertebrates to break down and eliminate DDT, but Win-gate suggests that even in infinitesimal amounts it may be having a subtle effect on man. "The long-range effects of hormonal imbalance may be graver than we suspect," he said recently. "Human behavior could be altered by DDT and, although it may seem farfetched, perhaps some of our social problems might be influenced by our contamination with DDT. After all, society is a delicate thing and the slightest change may throw it out of balance. While we don't have all the answers yet, we do know enough to stop using it now." Otherwise, as Governor Butler wrote, it may be "overlate."

Last June I spent four nights reclining on a down mattress on one of the cahow islets in the hope of seeing a chick depart. Wingate lay on a mattress beside me. These mattresses we had lugged ashore and carried on our heads up the lee cliff and across the crown of the islet. On the fourth night I remarked that in a better world than this one of us would be a girl. Wingate replied that he used to have the best line in Bermuda during College Week: Would you like to see my cahows? "Of course," he added, "then they found out I really wanted to watch the damn birds."

David Balcombe Wingate, the ruddy, strapping second son of a Scottish civil servant who emigrated to Bermuda in 1924, has two ruling passions: birds and what he is fond of calling "primeval Bermuda." This was not always the case. "Originally, I was curious about bugs and spiders," he said one night during our vigil on the islet. "Then I went through a period of egg-collecting. Between 10 and 12 I had an enormous phase in astronomy, which was replaced by an overriding interest in birds. I knew all the wood warblers before I was 12. It was worth your life to be considered a bird watcher as a teen-ager. It was not until I got to Cornell that I found there were others in the world as oddball as myself."

There is nothing Wingate would rather do than sit in his Boston Whaler at evening, on the edge of the deep, and watch shearwaters veering past, migrating from Tristan da Cunha to the Newfoundland Banks—it is a spectacle that greatly moves him. He has, however, contempt for the variety of bird watchers known as dickeybirders. "They're the most irritating creatures on earth," he said. "They've no ecological understanding. With them it's just like collecting stamps. I used to take dickeybirders out to see the cahows. Once they saw one they couldn't wait to get back to the hotel. Their sole enjoyment was in seeing a bird someone else hadn't. In fact, having seen it they'd much prefer it if the cahow became extinct.

"Every creature I've seen I regard as an individual and a character, and in each I've seen something of myself and therefore gained a better understanding of myself. For example, the cahows have taught me a little bit about the function of married life, the intimacy of the pair bond, the parents' faithfulness to the chick. This is being very anthropomorphic, but since all life springs from a common ancestor, I believe anthropomorphism is justifiable. Oftentimes I've lain out on this cold, barren rock, a bit sex-starved myself, and been jealous of them snug in the nest. Silly little things! They seem to have such a determination to survive! I can't picture a cahow saying, 'I'm determined to survive, I'm determined to survive,' but it's there instinctually. This applies equally to man. As much as man consciously appreciates and argues his mission in life, so much of this is decided by instinct. It begins to make you realize that you're part of the animal kingdom. How similar the cahows are to us! Our roots link us irrevocably with the rest of the kingdom. Man must live in balance with it. He cannot shake himself loose from it. It controls his destiny. All observations force this impression on me. We must retain a humility toward nature.

"I feel that I am morally right in trying to save the cahow, but it is a duty—not a penance. Although man is guilty of destroying the cahow he shouldn't blame himself for it. If I were an early colonist I'd have done the same. The birds walked into their huts at night, even right into the hearth fires. No wonder they thought they were gifts from God! Modern man is arrogant, he has a blatant assumption that he can control nature, his own destiny, turn everything to his own advantage. He doesn't see the locomotive roaring up behind him which will smash him to smithereens. Consider the land crabs. They're a bit of a pain in the neck. They spoil my lawn, girdle my trees. People say, 'That's no problem, it's easy to get rid of them.' Sure, it's easy, but by destroying land crabs how am I throwing everything else out of balance? That's why I admit I'm defeated by land crabs.

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