Ecoscience: Does Captive Breeding Solve Extinction Problems?

Paul and Anne Ehrlich's ecological research brings up the questions: Does captive breeding solve extinction problems? Does captive breeding of species and reintroduction to nature really work?


| July/August 1982



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Even if breeding and reintroduction programs could always be successful—and many have already proved to be failures—there are severe limits on the number of populations and species of animals and plants that can be maintained artificially.


PHOTO: MOTHER EARTH NEWS STAFF

The Ecoscience column asks the questions: Does captive breeding solve extinction problems? Does captive breeding and reintroduction work?

CAPTIVE BREEDING: A SOLUTION TO THE EXTINCTION PROBLEM?

Paul Ehrlich (Bing Professor of Population Studies and Professor of Biological Sciences, Stanford University) and Anne Ehrlich (Senior Research Associate, Department of Biological Sciences, Stanford) are familiar names to ecologists and environmentalists everywhere. But while most folks are aware of the Ehrlichs' popular writing in the areas of ecology and overpopulation (most of us—for instance—have read Paul's book The Population Bomb) . . . few people have any idea of how deeply the Ehrlichs are involved in ecological research (the type that tends to be published only in technical journals and college texts). That's why we're pleased to present this regular semi-technical column by these well-known authors/ecologists/educators.  

In our last column we discussed the role that seed banks can play in the preservation of the genetic diversity of crops. Does captive breeding solve extinction problems? Couldn't zoos and botanical gardens—you may well wonder—perform a similar task in the conservation of non-domestic animals and plants?

Well, a number of people, including some importers of animals for zoos and private collections, now contend that many organisms are doomed in the wild anyway. Why not, such individuals ask, preserve the creatures for posterity in captivity? Furthermore, some biologists have promoted programs of captive breeding as a means of rebuilding decimated wild populations . . . since it can be used to provide a stock from which reintroduction to nature could be attempted.

PEREGRINE FALCONS: THE "HAWK BARN"

In some cases such programs may indeed be able to make important contributions to the preservation of species. For example, the peregrine falcon was, not long ago, unable to reproduce in most of the United States (except in Alaska) because of high levels of DDT that interfered with the formation of strong eggshells. So, a decade back, Cornell University ornithologist Tom Cade began attempting to breed peregrines in captivity. And after several years of work, his efforts proved successful. Hundreds of birds have now been hatched in the Cornell "hawk barn". More than 200 of them have been released at 15 locations in the East . . . and of these, about 10% have survived to maturity. In 1979 four chicks were hatched, in the wild, by birds that had been raised in the barn and released.

The end result of Cade's program is still not certain, but it seems likely that, barring some unforeseen disaster, the peregrine will be reestablished. Of course, the 1972 ban on most uses of DDT in the United States has been a key factor in this potential success. That legislation removed the major cause of the deterioration of the peregrine's habitat. The bird can do well in otherwise quite highly modified environments, too. In fact, it will even thrive among city skyscrapers and hunt pigeons!





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