Zoo

A

Education

Modern zoos act as centers of education and are designed to make learning about animals an interesting and enjoyable experience. They provide visitors with the chance to see rare creatures, such as tigers, penguins, and giant pandas, that come from many different parts of the globe. Zoos also introduce people to their own local wildlife, offering a valuable learning experience in an increasingly urban world.

Most zoos provide educational programs aimed at a wide range of ages. For young children, a visit to a children's zoo provides an opportunity to see and touch animals other than household pets. Children can learn about the work involved in keeping animals and about the differences between domesticated and wild animals.

For older schoolchildren, many zoos conduct classes or day trips that focus on different aspects of animal biology and the impact of humans on animal life. These educational visits may include discussions about zoo management, the feeding and care of different species, and the methods used to encourage animals to breed in captivity. High school students learn about the complex issues that zoo professionals must consider on a daily basis, including strategies for controlling captive animal numbers so that animal populations do not outgrow the available space in a zoo. Students also learn about the need to strike the right balance between keeping species that attract visitors and keeping those in greatest need of protection.

A zoo’s staff may include scientists who conduct research in the wild. These experts often give lectures describing their experiences in remote places and, in many cases, under difficult conditions. In addition, many leading zoos post details of current research programs on their Web sites, enabling anyone with access to the Internet to keep up to date with new research.

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B

Captive Breeding

For zoos, encouraging animals to breed, particularly animals threatened with extinction, is work of prime importance. Some species, such as lions, breed almost too well in captivity, creating difficulties when their numerous offspring have to be fed and housed. But many other animals, such as cheetahs and giant pandas, are not nearly so adaptable. When kept in zoos, they often fail to breed. The world’s leading zoos now collaborate in captive-breeding programs to enable zoo animal populations to thrive and reproduce outside of their wild habitats, forestalling extinction and eliminating the need to capture wild animals to replenish captive populations. Ultimately scientists hope that animals that have been bred in captivity can be restored to the wild.

Captive breeding also guards against the loss of genetic diversity (the hereditary differences among individuals within a species). Genetic diversity enables species to adapt to and survive changes in their environment. In the wild, genetic diversity is maintained partly by the sheer number of animals in a particular population: A large breeding population means that animals have a wide choice of partners when they breed. In zoos, however, animals have a limited choice of partners, increasing the chance for inbreeding (mating between closely related animals). The genetic diversity of zoo populations steadily declines as a result of inbreeding. This growing genetic uniformity can have serious consequences. Because inbred animals share so many genes, they are likely to be equally vulnerable to disease and other forms of stress. If a potentially lethal disease strikes an animal population with a similar genetic makeup, the entire group may die.

To counteract this danger, scientists at the International Species Information System (ISIS), based in Apple Valley, Minnesota, maintain a database of genetic information about more than 250,000 living zoo animals from more than 50 countries. They also keep data on a further 1.4 million animals that have bred in captivity in the past. Zookeepers use this database to identify potential mating partners that are genetically distinct.

Scientists use a variety of captive-breeding techniques to boost animal populations. In a process called artificial insemination, scientists transfer sperm from a male animal into the uterus of a female animal. Sperm can be frozen and shipped to other locations, enabling scientists to breed animals from different zoos without the need to transport animals. In another captive-breeding procedure, called embryo transplantation, an embryo of a donor female is transferred to another female, known as the surrogate, of a similar but genetically different species. The surrogate mother carries the embryo through a full pregnancy and live birth. At present, embryo transplantation still has a high failure rate, although scientists have successfully used this technique to breed the Przewalski’s horse, a short, stocky horse that now exists only in captivity, and the gaur ox, an endangered type of wild cattle. Scientists hope that in the near future this technique can be used to increase breeding rates for endangered animals dozens of times over, reversing years of population decline.

In many cases, advanced technologies are not necessary to encourage breeding. Instead, zookeepers rely on research performed on the animals’ reproductive habits in the wild to improve captive-breeding success. Using this information, a zookeeper can tailor the way the animal is cared for so that the prospects of breeding improve. For example, in the case of cheetahs in the wild, research shows that courting adults stay apart except during the period immediately before and after mating. When they are ready to mate, cheetahs mark their territories with urine to leave a signature scent for prospective mates. Acting on this research, many zoos now keep prospective cheetah partners separate until both are ready to mate—a simple change that has produced some positive breeding results.

Scientists consider captive breeding a success when they create an animal population that can become self-sustaining in the wild. An example of a successful reintroduction to the wild is the Père David’s deer. This Asian deer was native to marshlands in northeast China before its habitat was destroyed more than 800 years ago and it became extinct in the wild. Since that time the species has been bred in zoos in China and later in Europe. In 1985 four Père David’s deer were released to the wild in a protected animal reserve in China, where they are now breeding successfully.

Other efforts to reintroduce captive-bred animals into the wild have had mixed success. The United States Fish and Wildlife Service initiated a captive-breeding program for the endangered red wolf in 1973. Since 1986 the red wolf has been gradually returned to the wild, first in the Alligator River National Wildlife Refuge in northeastern North Carolina and later in the Great Smoky Mountains National Park in western North Carolina and eastern Tennessee. While the red wolf population has thrived in the Alligator River National Wildlife Refuge, red wolves in the Great Smoky Mountains were unable to find enough food within the park, and malnutrition, disease, and predation contributed to poor survival rates for pups. Likewise, a third of the California condors that were bred in captivity and released to the wild have died. The condors reared in captivity were too tame to cope with natural dangers. In addition, many of the birds were poisoned by lead when they fed on animal carcasses that had been killed by lead buckshot.

C

Preservation in the Wild

Although zoos deal largely with captive animals, zoo scientists believe that captive breeding should not be considered a substitute for protecting species in the wild. In order to help threatened species, zoo scientists also work to safeguard natural habitats and educate local people about the value of their native wildlife.

The Wildlife Conservation Society (WCS) is one of many zoological institutions that carry out research programs across the world. WCS programs have included efforts to protect the chiru, an antelope that lives on the mountain plateaus of Tibet and Ladakh. The chiru sports a thick brown coat that is used to make fine wool. Although the sale of this wool is illegal under the Convention on International Trade in Endangered Species (CITES), the heavy demand for this wool on the black market has decimated the chiru’s population. The WCS has helped curtail the illegal trade of this wool by alerting consumers and retail stores to avoid buying these illegal wool products. The WCS also sponsored research into the behavior of the mandrill, a type of baboon that lives in West Africa's tropical forest. As part of this work, researchers fitted a small number of mandrills with collars that contain tiny radio transmitters. The scientists tracked the radio signals emitted from the collars to learn the location of the mandrills’ favored feeding habitats. Scientists hope to establish protected areas within these habitats to help the mandrills survive in the wild. In Peru WCS scientists sought to protect macaws and other tropical forest birds. Along with fieldwork to gather information about these birds, this program promoted ecotourism, attracting tourists to explore the natural wildlife. The money spent by ecotourists encouraged local people to protect wild birds instead of trapping and selling them as pets.

In Nepal, staff from the Zoological Society of London conducted similar work to protect the Asian rhinoceros. Nepal's Royal Chitwan National Park holds about 700 Asian rhinoceroses—nearly a third of the world's total population—and their security is vital for the future of the species. However, farmers surrounding the park saw the protected area as a source of additional grazing land, firewood, and other resources in an area where farmland is in short supply. Farmers also treated rhinos as pests when they strayed onto farmland and destroyed crops. Veterinary scientists from the Zoological Society set up clinics to help Nepalese farmers learn to manage smaller numbers of farm animals and increase their productivity. This program enabled farmers to use their small farmlands more economically so that they did not need to expand into protected parklands. The scientists also helped farmers recognize the value of wildlife reserves as a source of income for the area.

Despite their successes, these field programs sometimes encounter situations in which the needs of humans and wild animals are difficult to reconcile. In Central Africa, the fate of the mountain gorilla is a particularly disturbing case. Since the late 1970s, WCS scientists have been involved in a program to protect mountain gorillas by combating poaching and encouraging ecotourism. This work has been stymied by the continuing social unrest in Rwanda, Uganda, and Democratic Republic of the Congo. As a result, no more than 500 of these beleaguered primates are thought to survive.

D

Scientific Research

In addition to carrying out research in the wild, zoo veterinarians and other scientists study animals in zoos themselves. Among other research, zoo scientists study animal diets and the way animals normally grow in order to identify problems when animals fail to thrive. Research also focuses on animal behavior, particularly with species that live in groups. Zoo scientists study animals that have died in their care to identify any health problems that could be addressed by changing the way animals are looked after. Other scientific research performed on zoo animals has helped scientists develop new drugs, medical equipment, and surgical techniques that improve animal health.

IV

History of Zoos

The earliest known collections of captive animals date back more than 4,000 years, to the time of the first civilizations in North Africa and the Middle East. In ancient Egypt, the pharaohs acquired giraffes, monkeys, and gazelles from the southern edges of the Sahara. From India they imported chickens—at the time considered exotic birds—which proved to have a very practical value. In the Middle East, the kings of Assyria collected animals in the course of their conquests, keeping them in landscaped zoological gardens. Among them were Asian elephants and Bactrian camels, as well as crocodiles and hippopotamuses, which were kept in specially constructed pools.

In 1490 bc Queen Hatshepsut of Egypt launched what is thought to be the first animal collecting expedition. Five ships ventured as far as Somalia and returned with leopards, exotic birds, monkeys, and a giraffe. The animals were all housed in the queen’s palace menagerie. Two centuries later another Egyptian ruler, Ramses II, took pride in his collection of animals, particularly a lion that is said to have followed his master everywhere, even into battle. In 1000 bc Chinese emperor Wen Wang established a 600-hectare (1,500-acre) animal preserve. Called the Garden of Intelligence, this animal collection was established to study and learn from wildlife. These early menageries were kept purely for amusement and to exhibit royal wealth and power, and they were rarely open to the public.

Around the 4th century bc the ancient Greeks collected animals primarily for scientific education. During this time, increased interest in the natural sciences led to the development of a discipline for the study of animals, known as zoology. Alexander the Great, king of Macedonia, brought back exotic animals from his military conquests. Greek scientist Aristotle, who was Alexander’s teacher, studied these captive animals and compiled his observations in his Historia Animalium (350 bc), considered the first encyclopedia of zoology.

In ancient Rome animal collections were primarily used in brutal contests in large amphitheaters in which animals were forced to fight each other, or humans, to the death. In the 1st century bc Roman emperor Titus once put on a spectacle in which 5,000 animals were killed in one day, and 9,000 more were slaughtered over the next three months. The number of animals slaughtered during these spectacles was so massive that the populations of some animals, including leopards, became endangered. These animal games continued to flourish well into the 12th century, at which time their popularity declined.

In England early in the 12th century, during the reign of King Henry I, a royal menagerie was collected in a mansion in Woodstock in Oxfordshire. The menagerie included camels, lions, and lynx. A century later King Henry III moved the collection to the Tower of London. An animal collection remained in the tower for the next 500 years. The public was invited to view these animals for a small fee, and those who brought a dog or cat to feed to the lions were admitted for free.

When Spanish explorer Hernán Cortés entered Tenochtitlán (now Mexico City) in 1519, he found an enormous zoo. The Aztec leader Montezuma II had gathered a spectacular collection of animals. Ten ponds were home to flocks of waterfowl; hundreds of vivariums (glass enclosures) housed reptiles; and huge cages with bronze bars secured pumas, jaguars, sloths, and monkeys. More than 500 keepers attended the animals, including a team of nurses who tended sick animals and kitchen workers who prepared food for the animals.

With the start of European exploration and colonization, from the late 15th century onward, the first major collections of animals featuring species from several continents were established. When the explorers returned home from their travels, they brought many animals with them. These early animal collections, which included ornamental species such as parrots and peacocks, were assembled largely as curiosities.

By the 18th century, however, zoos began to reflect the growing scientific interest in the natural world. In 1793 a zoo was established in connection with the Jardin des Plantes (Botanical Garden) in Paris, France, fostered by figures such as French zoologist Georges Cuvier, the leading animal anatomist of his day. By the time the London Zoo opened in 1828, scientific study had begun to rival entertainment as a reason for collecting animals. During the mid- to late 1800s, thousands of species were brought back to Europe, where they were examined and classified by biologists. This flood of living animals—or their preserved remains—demonstrated the unsuspected vastness of the animal kingdom, particularly in the tropics.

Modern zoo design dates back to the early 1900s, when animal trainer Carl Hagenbeck opened a zoo in Stellingen, Germany. Hagenbeck housed animals in outdoor enclosures that used ditches and moats instead of bars. Many of these enclosures were built to imitate natural habitats, such as rocky mountainsides or open plains.

The first modern zoos founded in the United States were the Philadelphia Zoological Gardens in Pennsylvania, established in 1859; Central Park Zoo in New York, which opened in 1861; and Lincoln Park Zoo in Chicago, Illinois, which opened in 1868. By the early 1900s American zoos started to become involved in conservation work, as the growing human impact on North America's wildlife became steadily more apparent. Many zoos established collections of threatened native animals, but not all of the species succeeded in captivity. Most prominent among the failures was the passenger pigeon, once the most abundant bird in the world. As a result of overhunting, the species died out in the wild in the late 1800s, and the last living specimen, a 29-year-old captive-bred female named Martha, perished at the Cincinnati Zoo in 1914.

Most of today's zoos exhibit both common animals and ones that are much rarer. More recently, however, some zoos have been founded to concentrate solely on animals that are at risk. In India, for example, the Madras Crocodile Bank Trust breeds the endangered fish-eating gavial. In Australia, the Marsupial Cooperative Research Centre at the Perth Zoo raises endangered marsupials in captivity. Writer and naturalist Gerald Durrell established the Jersey Wildlife Preservation Trust in 1963 on the island of Jersey off the French coast. The trust has successfully raised a number of exotic animal species, such as the Mauritius pink pigeon, Bali mynah, and Rodriguez fruit bat, all of which are on the brink of extinction in the wild.

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