The extinction crisis has also inspired the creation of some high-tech, internationally accessible aids to captive breeding: studbooks, the International Zoo Yearbook (IZY), and the computer-based International Species Information System (ISIS).
Each zoological studbook lists details on all zoo-dwelling individuals of one particular species, wherever they may be in the world. An international record, it is the key to preserving a healthy genetic pool and keeping at bay that ‘silent stalker,’ inbreeding. The Berlin Zoo opened the very first zoo studbook when, in 1923, it began breeding the wisent, or European bison, driven to the edge of extinction by World War I.
To facilitate the global distribution of scientific data such as studbooks, IZY, and demographics data, ISIS went on-line in 1974 in the United States. Its expanding electronic network and its massive, ever-growing data base are helping zoos work together to turn the megazoo concept into a reality.
The biological tools embraced by the zoos include DNA fingerprinting, embryo transplantation, in vitro fertilization, and cryogenics (freezing sperm and embryos). DNA fingerprinting helps zoos identify parentage with 100-percent accuracy, which is essential in controlling inbreeding among species such as herd animals, where parentage is hard to monitor. Embryo transplantation and in vitro fertilization, meantime, accelerate reproduction. One way is by broadening the “parent” base of endangered species.
Their embryos can be inserted into closely related animals—even domestic animals—which then serve as surrogate mothers. This technique has seen a holstein cow give birth to a gaur (wild ox) and a domestic cat give birth to the highly endangered Indian desert cat. It also reduces the cost, risk, and trauma of transporting endangered breeding stock. A pack of embryos or frozen sperm is all that needs to be taken.
With the possibility of some species disappearing totally, a number of zoos have even embarked on the science of cryogenics—freezing sperm and embryos for long-term storage. This frozen zoo offers the prospect of offspring being born decades, perhaps even centuries, after extinction! Though fraught with uncertainties, it has been dubbed “last resort insurance.”
Studies in the Wild Help Zoos Make More Babies
A scientific study of animals, including their behavior in natural habitats, is critical to captive breeding and is the inspiration behind “immersion” exhibits. For animals to stay healthy and to breed, zoos must play to their instincts and keep them “happy.”
Male and female cheetahs, for example, remain visually isolated in the wild and communicate only by the scent in their urine and feces. The male’s nose tells him when the female is ready to mate, and then he stays with her for just a day or two. When the zoos learned of this behavior, they modified their enclosures to keep the sexes visually apart during all but the brief mating period, and it worked; cubs followed.
While absence makes the cheetah’s heart grow fonder, this is not so with the flamingo. It mates only when in flocks too large for most zoos to handle. So a zoo in England experimented—it “doubled” the size of the flock by means of a large mirror. For the first time, the birds actually started their dramatic courtship ritual! Do these examples give you an inkling of the complexity of earth’s wildlife? The zoos certainly have a mighty challenge.
How Realistic Is the Goal to Save the Animals?
Indicating the potential of the new program, some captive-bred species have already been reintroduced into their native habitats. Among these are the California condor, the European bison, the American bison, the Arabian oryx, the golden lion tamarin, and Przhevalski’s horse. Nevertheless, dark clouds hover over long-term prospects.
“Human society is so complex, and the world’s problems so numerous,” says Strategy, “that despite the growth in consciousness and concern regarding nature and the environment, it has not been possible to halt many of the destructive processes.” As a result, “conservationists must be prepared to find a means of weathering the expected critical period,” it adds. Naturally, this calls for cooperation at every level of society. Present cooperation, according to one science writer, is “woefully short of what is needed.” If the pressures driving extinction merely abate but do not reverse, even the best of efforts may still come to naught. Substantial and complete habitats—not just isolated pockets, which lead to inbreeding—must be created. Only then can zoos confidently release their charges back into the wild. But is such a hope realistic, or is it wishful thinking?
Straining credibility still further is the capacity of even a global megazoo. “The grim truth,” says Professor Edward Wilson, “is that all the zoos in the world today can sustain a maximum of only 2,000 species of mammals, birds, reptiles and amphibians”—the tip of the iceberg. Zoos thus have the unenviable task of deciding which species to cut out for conservation while the rest join the long list of those heading for oblivion.
For experts in the field, this raises an ominous question, In view of the interdependence of all living things, when will biodiversity fall to that critical threshold where it triggers an avalanche of extinctions that may snuff out much of the remaining life on earth, humankind included? Scientists can only guess. “The elimination of one or two or fifty species will have effects that we cannot predict,” says Linda Koebner in Zoo Book. “Extinctions are creating change even before we understand the consequences.” Meanwhile, says the book Zoo—The Modern Ark, “zoos remain among the most crucial garrisons of life in a planetary war of attrition, a war the extent of which cannot be predicted but one for which future generations will hold us utterly responsible.”
So is there any basis for hope? Or are future generations doomed to a world of biological monotony, with the abyss of extinction awaiting them?
Credit: Awake 1997 publised by JW
Bison and Cheetahs: Zoological Parks Board of NSW
Rhinoceros: National Parks Board of South Africa
Tiger and Elephants: Zoological Parks Board of NSW