For other uses see Zoo (disambiguation).
A zoological garden, abbreviated to zoo, is an institution in which living animals are exhibited in captivity. In addition to their status as tourist attractions and recreational facilities, modern zoos may engage in captive breeding programs, conservation study, and educational outreach.
Collections of wild animals were displayed in the civilizations of Mesopotamia, Egypt, and China. In medieval Europe some monarchs, monasteries, and municipalities continued to maintain collections of wild animals. The transition from menagerie, a predominantly private collection, to public institution marks the beginning of the modern zoo concept. Collections established during the nineteenth century began calling themselves zoological gardens. Throughout the nineteenth and twentieth centuries, many new zoos and related facilities were founded for very different motives and purposes.
The aims of zoo professionals have traditionally ranged from public education to conservation of biodiversity, as well as recreation. Many zoos define their aims as education, research, and conservation. Animal-rights groups claim that there is a wide gap between these claimed aims and actual practice, and that zoos have commercial and entertainment purposes in mind as well as financial profit. Zoos are frequently criticized by animal rights groups for varied reasons, including the quality of life of the animals they exhibit, and the perceived necessity or purpose of exhibiting captive animals at all.
Types of zoo include urban, open-range, safari, animal theme, roadside, rescue, sanctuary, petting, and specialized. The most traditional form of maintaining wild animals in captivity is keeping them in cages constructed of concrete or metal, in aviaries, or fenced paddocks. Most zoological gardens incorporated within international umbrella organizations are led by professionals such as zoologists or veterinarians.
The terms zoo and zoological garden, that refer to zoology (from Greek: ζῷον, zoon, "animal"; and λόγος, logos, "knowledge"), did not come into use until the modern zoo concept developed during the nineteenth century.London Zoo, launched in 1828, is the first place where wild animals are exhibited in captivity, to be called a "zoological garden" and, after 1829, when land on the opposite side of the road fronting the main gate was acquired, in the plural form "zoological gardens". The Zoological Society of London first used this term to describe its collection at Regent's Park, although this collection was simultaneously referred to as a menagerie. Most zoo founders of the nineteenth century operated with the term zoological garden to distinguish their institutions from the aristocratic and travelling menageries.The abbreviation zoo first appeared in print in Britain about 1847, when it was used for the Clifton Zoo, but it was not until some twenty years later that the shortened form became popular by a song called "Walking in the Zoo on Sunday".
To be precise, London Zoo was initially known as "the Gardens and Menagerie of the Zoological Society of London"; the term zoological gardens was itself a form of short-hand apparently first used in print in a guide-book in 1829.
Relatively new terms for zoos, which were coined in the late twentieth century, are conservation park or biopark. Adopting a new name is a strategy by some zoo professionals to distance their institutions from the stereotypical and nowadays criticized zoo concept of the nineteenth century. The term "biopark" was first coined and developed by the National Zoo, Washington, D.C. calling itself "Creating the Nation's first Biopark" in the late 1980s. In 1993, the New York Zoological Society changed its name to the Wildlife Conservation Society and rebranded the zoos under its jurisdiction as "wildlife conservation parks".
The most abundant evidence of the earliest zoos from Egypt derives from burial sites of about 2500 BC to 1400 BC. Throughout the entire period, written records -- on tablets, papyri, and tomb walls -- describe how pharaohs and other powerful citizens created zoos for their pleasure, prestige, and to satisfy scientific curiosity. Rulers gathered many of their animals from distant lands, frequently setting forth on expeditions for that purpose or receiving them as gifts from fellow leaders. They kept hyenas, monkeys, various antelopes, and mongooses. Proud of their collections, they took pains to ensure that their acquisitions would thrive and reproduce, often employing handlers to care for the creatures. The ancient Egyptians kept wild animals in a form of acclimatization which approached domestication. On tomb pictures dating from 2500 BC, at Saqqara, some ungulates including antelopes, gazelles and ibex are depicted wearing collars and leashes. Egyptian Queen Hatshepsut established a zoo in Thebes around 1490 BC. Hatshepsut's zoo contained exotic animals collected from what is today Somalia, and it included tall cattle, exotic birds, cheetahs, leopards, monkeys and a giraffe. During the Hellenistic period, Ptolemy I of Egypt (323-285 BC), who had a particular interest in natural history, founded a zoo in Alexandria.His son Ptolemy II developed the Alexandria zoo into the largest collection of captive animals assembled to that date. The animals were paraded at great ceremonies. In 285 BC, a procession for the feast of Dionysus included 96 elephants, 24 lions, 14 leopards, 16 cheetahs, 14 camels, a giraffe, a rhinoceros, hundreds of domestic animals as well as numerous birds.
In Mesopotamia, the kings of Sumeria, Babylonia, and Assyria were proud of their animal collections, which were symbol of power, wealth, and authority.The kings treasured rare specimens sent by their subjects and foreign dignitaries after searches and difficult transport.Animals came from Asia via trade with the Indus society and from Africa via trade with the Egyptians. The earliest zoo with large carnivores was probably in Sumer and was King Shulgi's (2094-2047 BC) of the 3rd Dynasty of Ur. Babylonian and Assyrian royal parks and gardens were where animals were kept.Tiglath-Pileser I, King of Assyria (1114-1076 BC), kept herds of deer, gazelles, and ibex from conquered territories in his park.Ashurnasirpal II, King of Assyria (883-859 BC), had wild bulls, lions, ostriches and apes.Sargon II, King of Assyria (721-705 BC), is reported to have been particularly fond of lions and falcons. Evidence of the earliest zoos from Mesopotamia comes from Assyrian palace reliefs of about 880 BC to 627 BC. Bas-reliefs from Assyrian royal palaces show monkeys, antelopes, camels, elephants, and other species brought to the Assyrian kings as tribute. 7th century BC stone reliefs from Nineveh depict the Assyrian king Ashurbanipal hunting lions, which seem to have been first caught and held in cages before being released and killed by hunting. A relief on one of the palace walls shows a Lion Hunt in which a captive lion is released from its transport crate into the animal park of Ashurbanipal, King of Assyria (668-627 BC) at Nineveh, Mesopotamia.Another well-known collector of lions was King Nebuchadrezzar II of Babylonia (605-562 BC).
In ancient China, wild animals, especially exotic species, were of interest to rulers and the wealthy class. Starting with the founder of the Shang dynasty (ca. 1500 BC), China's rulers built animal reserves.The Chinese empress Tanki, who ruled around 1150 BC, built a marble "house of deer".However, it was Wen Wang, founder of the Zhou dynasty (ca. 1000-200 BC), who built the first animal reserve, which he called Lingyou, commonly referred to as the "Garden of Intelligence". A more accurate translation would be "Garden for the Encouragement of Knowledge". This reserve and similar parks owned by the wealthy class of the Zhou period were large, walled-in natural areas that required their own staffs of administrators, keepers, and veterinarians, and housed a different animals like deer, fish, and "white birds with dazzling plumes". The rulers of the Qin (221-206 BC), Han (206 BC-AD 220), Tang (618-907), and Song (960-1279) dynasties continued the fashion of large royal parks, where birds and mammals were kept in cages for personal pleasure and the demonstration of wealth and power. In the thirteenth century, Marco Polo described the royal menagerie of Kublai Khan (1215-1294), founder of the Yuan Dynasty, in Shang-tu, which maintained leopards, tigers, lynxes and elephants, as well eagles and falcons used for hunting.In 1417, Yung-lo, a Chinese Ming Dynasty emperor, organised an expedition to Africa to collect a giraffe; apparently the emperor had a menagerie that included a zebra and other African animals. The fifteenth century Chinese explorer Cheng Ho returned in 1422 from Africa with at least one giraffe and one zebra.
Live animal collections also existed in the ancient Greek and Roman worlds.In the fourth century BC, Greek animal collections enabled Aristotle to write the first systematic zoological survey, The History of Animals, which describes about three hundred vertebrates known at this time.His student, Alexander the Great, sent information and specimens back to Greece from his eastern campaign. Alexander's travels east into Persia opened up a new source of animals for Grecian menageries. There are many publications about extravagant and bloodthirsty spectacles in Rome, involving wild animals.The 19th-century historian W.E.H. Lecky wrote of the Roman games, first held in 366 BC:"At one time, a bear and a bull, chained together, rolled in fierce contest along the sand ... Four hundred bears were killed in a single day under Caligula ... Under Nero, four hundred tigers fought with bulls and elephants. In a single day, at the dedication of the Colosseum by Titus, five thousand animals perished. Under Trajan ... lions, tigers, leopards, bears, elephants, rhinoceroses, hippopotami, giraffes, bulls, stags, even crocodiles and serpents were employed to give novelty to the spectacle ..." However, little has been written about the facilities of keeping those animals. By the second century BC, wealthy and influential Romans were keeping aviaries, fish ponds and menageries to show their power and prestige.The Romans had a special interest of birds. Although modern zoos claim to have built the first "walk through" aviaries, the idea originated with the Romans. Birds were not only kept for studies, but also for the table. They were allowed to fly freely in designated dining rooms incorporated within aviaries where some were caught and eaten. The Latin word vivarium referred to the stockyards and arenas where wild animals were held for public spectacles. In Rome, there were extensive animal holding areas, called vivaria, associated with the arenas that citizens might view. These were menageries of a sort. Each Roman emperor had a menagerie for triumphal processions and official celebrations, especially gladiatorial exhibitions in which animals were killed.At the dawn of the Christian era the Emperor Augustus (29 BC-AD 14) is recorded to have had over 3,500 wild and tamed animals from his menagerie killed in 26 celebrations, including 420 tigers, 260 lions, 36 crocodiles, and a number of elephants and rhinoceroses. However, some Romans, like Pliny the Elder (23-79) did have a scientific interest in animals.
In the New World, one of the earliest collections of animals was that of the Aztec emperor Montezuma II in Tenochtitlan (now Mexico City). It contained several buildings, flight cages and numerous gardens, lakes, streams, and ponds for its birds, mammals and reptiles.Hundred of gardeners and animals keepers tended the collections and the grounds.Montezuma 's imperial collections even had dedicated veterinary staff to care for sick animals.These animal collections were destroyed during the Spanish conquest (1519-1521) by Hernando Cortés.
At the middle of the 16th century, Hessen was ruled by Landgraf Wilhelm IV. In 1571, he established a zoological garden at the Sababurg, a castle in the Reinhards Forest not far from Kassel.The prime purpose of the wild animal park was to furnish the kitchens with meat.In 1971, this area became Tierpark Sababurg.
Menageries owned by monarchs and wealthy aristocrats can be seen as the predecessors of the modern zoological gardens.One of these aristocratic menageries was at the Palace of Versailles during the reign of Louis XIV.The oldest existing zoo, the Tiergarten Schönbrunn in Vienna, evolved from an aristocratic menagerie, founded by the Habsburg monarchy in 1752.
The transition from menagerie, a predominantly private collection, to public institution marks the beginning of the modern zoo concept. Collections established during the nineteenth century began calling themselves zoological gardens. In some cases this was simply fashionable since zoos were considered professionally managed facilities, whether they were or not. In other cases there was an emphasis on education and science rather than on entertainment.
The first modern zoo, established particularly for scientific and educational purposes according to its founders, was the Ménagerie du Jardin des Plantes as part of the Muséum national d'histoire naturelle in Paris (1793).The Paris Ménagerie was the first genuinely scientifically-oriented garden, the first one to be directed by a naturalist, and it can thus lay a legitimate claim to be the first modern zoo. It was, significantly, laid out like a picturesque park -- a semblance of Nature emphasized by Rousseau -- while the buildings themselves housed caged animals as if in museum display cabinets. About thirty years later, the Zoological Society of London was founded in 1826 by Stamford Raffles.The Zoological Society of London stated in its charter that its aim was "the advancement of zoology and animal physiology and the introduction of new and curious subjects of the animal kingdom".The members of the Zoological Society of London adopted the idea of the early Paris zoo when they established London Zoo as a scientific zoo in 1827. It opened on April 27, 1828, in Regent's Park, admitting members and their guests. Only in 1847 were working people allowed in, for a shilling. London Zoo admitted paying visitors to aid funding of its scientific work.The taxonomic presentation of animals at the London Zoo became the model for the nineteenth century.The success of London Zoo set off a Victorian wave of similar establishments.
Wealthy citizens and interested scientists founded zoological societies following the standard of the Zoological Society of London.The Royal Zoological Society of Ireland was founded in 1830, "to form a collection of living animals on the plan to the Zoological Society of London". In 1833, Dublin Zoological Gardens opened in Phoenix Park. Bristol Zoo, the Zoological Garden of the Bristol, Clifton and West of England Zoological Society, was the very first one to be founded through a shareholding company in 1835. It was opened in 1836 in the Clifton section of Bristol, England.
On continental Europe, the first modern zoos in Belgium and the Netherlands were established in their major ports.
The first of these societies was established in Amsterdam, Netherlands in 1838. It was the Zoologisch Genootschap Natura Artis Magistra (Zoological Society Natura Artis Magistra), which received the supplement "Koninglijk" (Royal) in 1852.In 1838, an appeal for the formation of a zoological society was published under the title, Natura Artis Magistra (Latin for Nature is the Master of Arts) and about 120 people joined the new society. Artis, as the Amsterdam Zoo is popular known, opened on May 1, 1838.
The first attempt to establish a zoological garden in Belgium, came with the formation of a society with royal patronage in 1841. The organization, the Société royale de zoologie à Anvers (Royal Zoological Society of Antwerp), had opened Belgium's first modern zoo in Antwerp in 1843.
The history of modern zoos in Germany began in 1841, when King Friedrich Wilhelm IV presented to the city of Berlin his pheasantry in the Tiergarten and all the animals on the Pfaueninsel, together with their cages and animal houses, as the basis of a municipal zoo.The Berlin Zoo, was constructed in 1841 on the site of the former royal pheasant run in the Tiergarten at Charlottenburg. Friedrich Wilhelm IV not only donated in 1841 the site of his pheasantry to the newly-founded shareholders' association Zoo Aktiengesellschaft, but also donated 850 animals from the royal menagerie, which moved in 1844 from Peacock Island (“Pfaueninsel”) to Tiergarten. The Berlin Zoo, the first in Germany, was opened on August 1, 1844, and today houses more than 14.000 species.
On August 8, 1858, Germany's second zoo was opened by citizens of the city of Frankfurt, the Frankfurt Zoological Society. The first grounds were leasehold land, and a new location had to be found. The new Frankfurt Zoological Garden was built in the style of a landscape garden, and inaugurated on March 29, 1874.
Cologne Zoological Garden, the third German zoo, was founded by citizens of Cologne, who formed a shareholding company, and opened in 1860.
Zoo Dresden, Germany's fourth zoo, was founded in 1861. The first plans for the new zoo were drawn up by German landscape architect Peter Joseph Lenné.The founding of the zoo was strongly supported by the king of Saxony as well as the people of Dresden, some of whom formed a zoological society to assist the endeavor.An area of 32acres within a large park adjacent to the city center was given to the society to use for the zoo.
The Zoologische Gesellschaft in Hamburg (Zoological Society of Hamburg) was a shareholding company chartered on July 10, 1860.A 32acres site was leased from the corporation of Hamburg in August 1861, initially for 50 years (later renewed every ten years). By November 1862 most of the infrastructure and the animal houses had been completed.Alfred Edmund Brehm appointed director took up his post in January 1863.The Hamburg Zoological Garden was opened to the general public on May 17, 1863. The society-run zoo was one of Europe's major gardens until it closed down, a victim of the Great Depression and competition from Hagenbeck, in 1930.
In 1860, the citizens of Hannover formed a society to establish a zoo in the city on the River Leine, and on May 4, 1865 the Zoologischer Garten Hannover opened its gates.The city went into partnership with the Ruhe animal trading company from Alfeld to the south of Hannover.The entire Hannover Zoo was leased by Firm Hermann Ruhe between 1931 to 1971 and became during those years the animal trader's "shop window".
The world’s first acclimatization society was the Société Zoologique d’Acclimatation, founded in Paris in 1854. The founding president was Isidore Geoffroy Saint-Hilaire, professor of zoology at the Muséum national d'histoire naturelle and director of the Ménagerie (created in 1793).In 1860 Isidore and his son, Albert Geoffroy Saint-Hilaire, opened Jardin Zoologique d’Acclimatation, located in the Bois de Boulogne, west of Paris.
The idea to create a zoological garden in Moscow came in 1857 when professors at the Moscow University established the first Society of Acclimatization in Russia.In 1862, the society was reorganized and given the name Tsar's Society for the Acclimatization of Plants and Animals.In 1863, this society was eventually able to buy property for its future zoo, where it still exists.The opening ceremony of the Moscow Zoological Gardens took place on February 12, 1864.A second Russian zoological garden was opened only one year later. The St. Petersburg Zoo opened to the public at its present site on August 1, 1865.The Moscow Zoo was designated national property in 1919. The zoo in St. Petersburg was nationalized in 1919, the same year as the one in Moscow.
In the United States, physician William Camac initiated the incorporation of the Zoological Society of Philadelphia in 1859. According to the society's charter, "The object of this Corporation shall be the purchase and collection of living wild and other animals, for the purpose of public exhibition at some suitable place in the City of Philadelphia, for the instruction and recreation of the people." The American Civil War interrupted these efforts so that the opening of the Philadelphia Zoo delayed until July 1, 1874.Some years ago, the Central Park menagerie evolved from gifts of exotic pets and other animals informally given to the Park, beginning, apparently, with a bear and some swans deposited near New York City's arsenal on the edge of Central Park in 1859. About 1861/62, a smaller zoo with lower standards had been already established in New York City, the Central Park Zoo. In 1864 it received charter confirmation from New York's assembly. The Baltimore Zoo actually had its beginnings as early as 1862, when the first of many citizens gave animals to Druid Hill Park for public display.It was officially created by act of Maryland state legislature on April 7, 1876.The Maryland state legislature had authorized the Baltimore Park Commission to establish a zoological collection. Lincoln Park Zoo in Chicago, Illinois, was founded in 1868, when the Lincoln Park commissioners were given a gift of a pair of swans. Roger Williams Park Zoo in Providence, Rhode Island was established in 1872 with a small collection of mostly native animals. The Zoological Society of Cincinnati was established in 1873. A site was acquired the following year, and the Cincinnati Zoo opened on September 18, 1875. Other zoos in the United States began as menageries, when animals were donated to a park system and city fathers had to find a place to house them.The zoos in Buffalo, New York (1875); Binghamton, New York (1875); and Cleveland, Ohio (1882) are examples of this type of "startup". When the first American zoological gardens came into existence, only a few supporters of the early animal welfare movement spoke out against zoos. Humanitarians protested cruelty in training animals for circuses more often than they opposed zoos. Their concerns were that zoo animals were healthy and well cared for, and not subjected to cruelty or pain.
In March 1889 an Act of Congress authorized the formation of a National Zoological Park Commission to select and purchase land for a zoological park in the District of Columbia "for the advancement of science and the instruction and recreation of the people".In April 1890, United States Congress passed another act, placing the National Zoological Park under the direction of the Smithsonian Institution's Board of Regents.First animals arrived in 1891 at the Washington Zoo.
The New York Zoological Society (now the Wildlife Conservation Society) was incorporated on April 26, 1895. Objectives of the society were "to establish and maintain in New York a zoological garden for the purpose of encouraging and advancing the study of zoology, original researches in the same and kindred subjects, and of furnishing instruction and recreation to the people".The New York Zoological Park (the Bronx Zoo, now the Wildlife Conservation Park) opened on November 8, 1899.
The most extensive zoo in the United States is the San Diego Zoo, containing over 800 species of animals on an area that stretches more than 100acres.The San Diego Zoo grew out of exotic animal exhibitions abandoned after the 1915 Panama-California Exposition. Dr. Harry Wegeforth founded the Zoological Society of San Diego, meeting October 2, 1916 and initially following precedents set by the New York Zoological Society. A permanent tract of land in Balboa Park was set aside in August 1921, and the zoo began to move in the following year.
The history of modern zoos in India began around the middle of the nineteenth century. The first zoo was probably Marble Palace Zoo, started in 1854 by Raja Mullick Bahadur in the private mansion in the center of Calcutta. There were many mammals and birds in this collection.  In 1855, a zoo was set by the Municipality of Madras in a 20-4NaN-4 area near the Railway station. It was closed down in 1980 and shifted to a new 1260acres site, known as the Arignar Anna Zoological Park, Vandalur. This is a modern zoo of India. 
The Zoological Society of Victoria was established in 1857 and was the first to develop a major zoo in Australia.Its priorities had shifted from collecting and displaying exotic animals to importing large numbers of unusual domestic animals.To reflect this emphasis, the society renames itself the Acclimatisation Society of Victoria in 1861 and concentrated its efforts on acquiring useful animals.The animals in question fell into three broad categories: economic, game and ornamental.The Royal Melbourne Zoological Gardens opened on the Royal Park site in 1862.
Ueno Zoo opened its gate in 1882 in heavily wooded Ueno Park, Tokyo, as part of the national museum, and was the first modern zoo in Japan.Kyoto Zoo was the second modern zoo in the country, opening in Okazaki Park, Kyoto, in 1903 to commemorate the wedding of the crown prince, who later became emperor.The birth of the third zoo followed in 1915 in Osaka, a municipal facility known as Tennoji Zoo.The imperial facility gave the Ueno Zoo to the City of Tokyo in 1924 to commemorate the wedding of another crown prince.
Throughout the nineteenth and twentieth centuries, many new zoos and related facilities were founded for very different motives and purposes: contribution to the advancement of science; experiments in acclimatization and domestication; access to nature; popularization of science in a refined, light and pleasurable way; support for the control of the wild; and creation of a trade of animals. Cultural and philosophical attitudes as well as political developments such as imperialism had an impact on the appearance and aims of zoological gardens. Human beings were sometimes displayed in zoos along with non-human animals, supposedly to illustrate the differences between people of European and non-European origin (“Human zoos”). According to historians Eric Baratay and Elisabeth Hardouin-Fugier the zoos of that period reflected the determination of imperialist nations to classify and dominate.
German animal dealer, and circus and ethnographic showman, Carl Hagenbeck (1844-1913) was an innovator in the history of the modern zoological park. Carl Hagenbeck opened his Tierpark ("animal park") to the public on May 7, 1907, in what was the northern suburb of Stellingen, in Hamburg.Carl Hagenbeck's Tierpark was the first in the world to combine the modern zoo elements of ersatz landscapes, moated, barless enclosures, and mixed-species exhibits of largely acclimatised animals.
Rome Zoo appears to be an exception, as it developed from the direct involvement of Carl Hagenbeck and his Stellingen team, particularly Heinrich Hagenbeck, Moritz Lehmann and Urs Eggenschwyller.In Italy, a conference was held on November 12, 1908, to introduce Carl Hagenbeck and his project to the Romans. After securing the advice of Carl Hagenbeck, a Society for the Zoological Garden was founded in Rome at the beginning of 1909. It received from the municipality an area of about 25acres at the Villa Borghese park.Work began in May 1909 and was almost completed by October 1910, in time for the Universal Exposition of Rome in 1911. The Rome Zoo was inaugurated on January 5, 1911.
In 1931, a small zoo was built by the Hagenbeck's firm for the Colonial Exposition organized by Lyautey in Paris. The popular success of this temporary zoo inspired the Muséum national d'histoire naturelle to create a new zoological garden inaugurated on June 2, 1934 in the Bois de Vincennes, east of Paris.
The most important zoo in the former German Democratic Republic (GDR), the Tierpark Berlin-Friedrichsfelde, opened in 1955.Because of its connections and animal dealings with Eastern European zoos, it contains some of the rarest species.Its former connection with the Academy of Science of the GDR supported research at Tierpark Berlin-Friedrichsfelde.It became one of the leading zoos of the world with many rare breeding groups of birds and mammals.
In the 1950s, Bernhard Grzimek used the zoo and the zoological society of Frankfurt to popularize the idea of nature conservation. When ecology emerged as a matter of public interest through the 1970s, a few zoos began to consider making conservation their central role, with Gerald Durrell of Jersey Zoo, George Rabb of Brookfield Zoo, and William Conway of Bronx Zoo leading the discussion. Since then, zoo professionals became increasingly aware of the need to engage themselves in conservation. As a modern ark, the concept of frozen zoo had been added to both captive breeding (“ex-situ conservation”) and conservation in the wild (“in-situ conservation”).Especially in United States, the new zoo concept had been developed. The changes at zoos have served both the ideology of environmentalism and the day-to-day needs of zoos to maintain their collections. Many of contemporary zoos led by professionals show fewer species and display social animals in groups; landscape immersion exhibits replicate animal habitats. The zoological garden of the nineteenth century eventually evolved into the biopark, or conservation park, of the late twentieth century.The conservation park concept is quickly being superseded with an even newer one, the environmental center of the twenty-first century. In effect, it is announced that the role of zoos will be changing in the 21st century.Instead of the living museums that they were in the 20th century, more and more zoos will become environmental resource centres in which ecosystems and survival of species are supported.It is also proposed that, as possible agents for conservation, visitors to zoos should play an active role in this process.
See also: List of zoos.
Zoo professionals proclaim exalting and demanding aims for their institutions, from educating the public to conservation of biodiversity. Many zoos define their aims as recreation, education, research, and conservation.Animal-rights groups claim that there is a wide gap between the claimed aims and actual practice, and that owners of zoos have commercial and entertainment purposes in mind to increase their financial profit. Some zoos work to save endangered species, but most animals in zoos are bred in captivity for the purpose of public display, not species protection. In his 1985 critique of zoos, philosopher Dale Jamieson asserted that zoos generally do not live up to their own goals, that zoo animals are deprived of freedom for little social or scientific good, and that zoos cause suffering without producing compensatory benefits for animals or people. Jamieson argues that a moral presumption against keeping animals in captivity outweighs any benefit that might accrue from education, science, or species preservation. The animal rights philosophy refuses zoos as a matter of principle. Keeping wild animals in captivity is seen as human domination over other creatures. French historians Baratay and Hardouin-Fugier see zoos as an allegory for the contradictions of modern Western societies: "The zoo made concrete, in an enclosed space, what society wanted to do in nature, as, with the advance of urbanization, people felt an increasing need to preserve the wild. But the desire remained unrealized, because Western society did not want its methods called into question, and because, in the final analysis, it preferred to transplant, delimit, cultivate and arrange nature however and wherever it liked, rather than leave places truly free of human influence."
Recreation, which is close to entertainment and pleasure, does not benefit the welfare of the zoo animals, but that of the zoo visitors. Jamieson points out that "we should have the honesty to recognize that zoos are for us rather than for the animals". According to Swiss zoologist Heini Hediger recreation is one of the most important aims of the modern zoo in the face of proceeding urbanization and alienation from nature. People, especially from urbanized areas, should be given the opportunity to relax and to enjoy a naturalistic environment in their very neighbourhood.
Since the beginning of the modern zoological gardens education and therefore the propagation of biological knowledge has been one of the most prominent aims claimed by zoo professionals. Already in 1829, London Zoo published its first guide to the zoo. Today’s educational efforts of zoos concentrate mostly on ecological and conservation issues. The idea of conservation education at zoos has a longer history than it is often acknowledged. This idea was foremost among the goals of the Arizona-Sonora Desert Museum as it was planned in the early 1950s. Animal exhibits were one component of the museum, which was begun with the goal of educating the public about the plant life and scenic value of the desert. Although the museum's focus was regional, and it was not a traditional zoo, directors of many American zoos looked to it as a model. Many zoos now have an education department, a classroom, and full time educational officers. Edinburgh Zoo has pioneered a scheme called "interlink" which combines the resources of the zoo, local museums, and the botanical gardens to create educational courses. Like several other zoos it offers teachers a range of courses from day trips with infants to intensive courses for advanced students. In 1991, over 50,000 students were involved with structured courses at Edinburgh Zoo. However, critics say that there is no educational value in exhibiting wild animals in artificial environments. According to them true respect for wildlife could only be stimulated by learning about animals in their natural habitat.
Classical zoological gardens played a role in research in comparative anatomy and physiology in the nineteenth century. Important scientists, such as Cuvier, Alfred Brehm and Paul Matschie, used zoos for their studies.
Oskar Heinroth, the director of the aquarium at the Berlin Zoological Gardens during the early decades of the twentieth century, coined the word ethology and was the first to articulate its general mission: a scientific study of animal behavior that would operate through comparative methods, like the already well-established of comparative anatomy.
Beginning in 1934, the brothers Lutz and Heinz Heck, two German directors of the Berlin and Munich Zoos respectively, did indeed experiment in "back-breeding" two species of extinct European ungulate: the aurochs (Bos primigenius) and the tarpan (Equus gmelini).
In 1950, Heini Hediger highlighted how a modern zoo represents an institution which has always been indebted throughout its development to scientific enquiry, and thereby stressed the importance of zoos being active in all aspects of potential research. He also recorded how the biology of zoological gardens opens up a complex field of study, ranging from zoology to human psychology, from ecology to pathology; concluding how the various links between zoo biology and animal psychology should be an on-going investigatory process.Heini Hediger developed zoo biology as a special branch of biology. Zoo biology translates the ideas and perceptions of others sciences into the practice of zoological garden management and gives stimulus to the use of zoo research in other sciences.
Contemporary research efforts focus on ethology and conservation breeding. According to William Conway zoo science would contribute basic biological information and technological know-how to the increasingly demanding tasks of wildlife care in constricted habitats.
Up to now, only a few species such as the Przewalski’s Horse, the American Bison, or the California Condor could be saved from extinction and reintroduced to the wild. The American Bison, for example, was close to extinction at the beginning of the twentieth century. In 1907, the Bronx Zoo led by William T. Hornaday was the first zoo to help the American Bison Society with its reintroduction project, sending 15 bison to the Wichita Forest Reserve in Oklahoma. Other reservation herds were established in succeeding years using additional zoo-bred animals. By 1933, there were 4,404 bison in the United States and 17,043 in Canada.  Although most species maintained in zoos are not endangered, and those that are will likely seldom be released into natural habitats, biologist Colin Tudge emphasizes the urgency of ex-situ conservation in zoos in the face of increasing threat to natural habitats. In 1993, the World Association of Zoos and Aquariums (WAZA), formerly known as the International Union of the Directors of Zoological Gardens, produced its first conservation strategy. In November 2004, WAZA adopted a new strategy that sets out the aims and mission of zoological gardens of the twenty-first century. The captive breeding of endangered species is coordinated by cooperative breeding programs. Under the auspices of WAZA, 182 International Studbooks are kept. These studbooks are coordinated by the Zoological Society of London. About 810 animal species and subspecies are managed under cooperative breeding programmes at the level of the regional association members such as the Species Survival Plan (SSP), established 1981, or the European Endangered Species Programme (EEP), established 1985.
But critics point to the marginal contribution of zoos to the preservation of biodiversity. Andrew Linzey, director of the Oxford Centre for Animal Ethics, argues that zoos make a "minuscule contribution to conservation." Most conservation experts agree that few of the rare or endangered species can be saved from extinction by breeding them in captivity. In 1990, the International Union for the Conservation of Nature (IUCN) drew up an action plan for the survival of 1370 species. It considered that the reintroduction of captive bred animals could assist in the conservation of only 19 species (1.4 percent). The difficulties associated with ex-situ conservation are illustrated by the captive breeding program for the critically endangered Sumatran rhinoceros. Between 1984 and 1996, 40 Sumatran Rhinos were transported from their native habitat to zoos and reserves across the world. After years of failed attempts and a dramatic decline of the captive population, one individual gave birth to a healthy male calf at Cincinnati Zoo in September 2001. This was the first successful captive birth of a Sumatran Rhino in 112 years. Two other calves followed in 2004 and 2007. Despite the recent successes in Cincinnati, the captive breeding program has remained controversial. Proponents argue that zoos have aided the conservation effort by studying the reproductive habits, raising public awareness and education about the rhinos, and helping raise financial resources for conservation efforts in Sumatra. Opponents of the captive breeding program argue that losses are too great; the program too expensive; removing rhinos from their habitat, even temporarily, alters their ecological role; and captive populations cannot match the rate of recovery seen in well-protected native habitats.
Urban zoos are the classical zoological gardens that stand in the tradition of the nineteenth century zoo concept, even if some of them changed their names to Conservation Park or Biopark. Most of them are relatively small in size and based within cities or urbanized areas, a fact that often complicates the construction of more sizable enclosures. In Europe, a famous urban zoo is the Antwerp Zoo in Belgium, right next to the central station of the city. In the USA a good example is the Cincinnati Zoo.
Some zoos concentrate on animals of geographical regions (geozoo); other zoos have developed ecological exhibits based on ecosystems rather than geographical areas, or attempt to exhibit their animals in a different way of the opening by night (night safari).Reopened in 1928 in Munich, Germany, Tierpark Hellabrunn was called for the first time the Geo-Zoo because the animals are grouped according to continent of origin on grounds which resemble the animals' natural habitats.The Indianapolis Zoo, opened in 1988 in White River State Park, downtown Indianapolis, Indiana, was organized around the concept of biomes such as temperate and tropical forests, plains, deserts, and oceans. In 1994, the opening of the Night Safari, conceived by Sri Lankan Lyn de Alwis and developed by the team at the Singapore Zoological Gardens led by Bernard Harrison, created the simple but totally unique concept of simulating appropriate animal species in a national park, to be viewed only at night, with subtle theatrical lighting simulating moonlight. Some 1,000 animals can be seen in a tropical rainforest setting.
A number of open-range zoos have been established since the mid-1920s in rural surroundings. The prototype is Whipsnade Park, England, established by the Zoological Society of London on the Chiltern Hills in 1926 and opened in 1931 (600 acres, 2.4 km²). Urban zoos started to develop out of city zoos -- commencing with Whipsnade for London, followed by such developments as Planckendael (1956) for the Antwerp Zoo and Tama (1958) for Ueno Zoo in Tokyo.Fewer species are exhibited in such zoos than in urban zoos, but they are mostly kept in more sizable enclosures.
Conservation centers were established for the first time in the United States for the purpose of off-site captive reproduction and conservation at the San Diego Wild Animal Park (Escondido, California, 1972), St. Catherines Wildlife Conservation Center (Midway, Georgia, 1974), and Conservation and Research Center (Front Royal, Virginia, 1975).San Diego, New York and Washington Zoos respectively manage these centers, and all are off exhibits (not open to the public) except the San Diego Wild Animal Park. After 30 years of animal research, Bronx Zoo closed St. Catherines Island preserve at the end of 2004. In North America, the seventies witnessed a boom in so-called "utopian zoos", sprawling complexes of several hundred acres often linked by trams or monorails. From San Diego (1972) to Toronto (1974), Minneapolis (1978) to Miami (1981), these elaborate facilities provided animals with vast territories to roam and offered visitors yet another version of zoo naturalism. The largest zoo in terms of size is the 1,800 acre (7 km²) San Diego Wild Animal Park in the San Pasqual Valley, California, that is run by the Zoological Society of San Diego.In 1974 the Metropolitan Toronto Zoo was open to the public. Encompassing 710acres, it is located at Scarborough, Ontario.One of only two American state supported zoos is the North Carolina Zoo located in Asheboro, North Carolina and opened in 1974 as a temporary facility while the permanent zoo was being built, and in 1979 as a permanent facility.At 1458acres, it is the largest walk-through natural-habitat zoo.The almost 1500acres park includes a 300acres recreation of Africa’s wilderness and a 200acres representation of North America’s landscape. The Minnesota Zoo, opened in 1978, is a agency of the state of Minnesota. It was built in Apple Valley, Minnesota, a suburbanizing rural area of Minneapolis-St. Paul, and organized its animals by their living environment, featuring outdoor and indoor themed walking trails: Minnesota Trail, Northern Trail, and Tropics Trail.Construction of Miami MetroZoo began in 1975. It opened on December 12, 1981. The zoo is on 740acres.Zoos in Columbus, Cincinnati, Cleveland and Toledo helped create the Wilds, a 9150acres breeding facility opened to the public in 1994, in south-eastern Ohio.
In Australia, urban zoos developed out of city zoos between the seventies and the nineties.The Western Plains Zoological Park located near Dubbo, New South Wales was opened to the public in 1977 to provide more space in a 750acres area than was available at the Taronga Zoo in Sydney. The Werribee Open Range Zoo near Melbourne, Australia, concentrates on displaying animals living in a wide open savanna. This 500acres zoo is managed by the Zoological Parks and Gardens Board of Victoria which also manages Melbourne Zoo.Public visitation began in 1983. The Monarto Zoological Park was opened to the public in 1993 on an area of 2500acres, located in Monarto, South Australia. It is administered by the Royal Zoological Society of South Australia, along with the Adelaide Zoo.
A safari park is a zoo-like commercial tourist attraction where visitors can drive in their own vehicles and observe the wildlife, rather than viewing animals in cages or small enclosures. Most safari parks were established in a short period of ten years, between 1966 and 1975.This kind of zoo was started by Lord Bath in 1966, with his Lions of Longleat, on his estate in Wiltshire, to be followed in the next year by the commercial venture, Lion Country Safari, on 640acres near West Palm Beach, Florida.
An animal theme park is a combination of an amusement park and a zoo, mainly for entertaining and commercial purposes. Marine mammal parks such as Sea World and Marineland are more elaborate dolphinariums keeping whales, and containing additional entertainment attractions.
Another kind of animal theme park is Disney's Animal Kingdom in Orlando, Florida (550 acres, 2.2 km²) or Busch Gardens Africa in Tampa, Florida (335 acres, 1.36 km²). These commercial parks are similar to open-range zoos according to size, but different in intention and appearance since they contain far more entertainment elements (stage shows, roller coasters, mythical creatures etc.).
There are hundreds of substandard wildlife attractions throughout the United States and Canada called roadside zoos. These mainly amateur facilities are usually privately owned and occasionally accredited by the American zoo organization AZA. The focus is on amusing customers, rather than on meeting the needs of the animals. Roadside zoos often lack trained, experienced animal care staff, proper funding and safety practices. Animals are confined to small, barren, often filthy cages, and suffer poor welfare as a result of inadequate housing, care and diet. Roadside zoos breed animals in order to have a constant supply of cute babies to attract the public. Big cat rescues, primate rescues, and native wildlife rescues are overwhelmed due to the constant influx of animals coming out of roadside zoos.
Animal welfare supporters have funded the construction and set-up of sanctuaries for wild animals. The animal welfare organization WSPA established several of these facilities for rescued bears worldwide. According to the organization those in Greece and Turkey have helped stamp out the tradition of forcing bears to perform tricks for public entertainment. Another type of sanctuary takes the form of a rehabilitation and release center. An example of this is the Idaho Black Bear Rehabilitation Center, where orphaned bear cubs are cared for and prepared for release back into the wild. Another sanctuary, especially for apes and primates, is 65 acre (0.26 km²) Monkey World near Pool, Dorset, England. Set up in 1987 it was originally intended to provide a home for abused chimpanzees used by Spanish beach photographers, but is now home to many different species of primates. In India, Amte's Animal Arc is an animal rescue run by the Lok Biradari Prakalp.
A petting zoo, also called children's farms or children's zoos, features a combination of domestic animals and wild species that are docile enough to touch and feed. To ensure the animals' health, the food is supplied by the zoo, either from vending machines or a kiosk nearby.
The most traditional form of maintaining wild animals in captivity is keeping them in pits (“bear pits”), in cages constructed of metal bars or concrete, in aviaries, or fenced paddocks, although many zoos replaced these by more elaborate and larger enclosures that attempt to replicate their natural habitats, for the benefit of the animals and the visitors.
The traditional structures in exotic styles in zoological gardens of European cities in the nineteenth century were thought appropriate as the home of wild creatures from foreign parts: the Egyptian temple in Antwerp Zoo (1856), the Moorish-looking elephant house at the Cologne Zoo (1863), the Indian pagoda for elephants in Berlin Zoo (1873), the Turkish elephant house at Basel (1891).
The first exotic design for a zoo building was the Egyptian temple at the Antwerp Zoo. Antwerp's Egyptian temple was a faithful reproduction of an ancient temple on the Isle of Philae. It was built for elephants, giraffes and zebras, in 1856.Its architect, Charles Servais, used the Egyptian style for all kinds of African animals.
Following the example of Zoo Antwerpen in Belgium, some of the Berlin Zoological Garden's houses were built in a picturesque, exotic style. Accordingly, 1871 witnessed the opening of the magnificent Antelope House in the Moorish style.This building was also the Giraffe House, which was elliptical in plan, was decorated with four minarets, each pierced with a large golden sphere. The Antelope House was followed by the Indian style Elephant House (1873), the Japanese Wader House (1897), the picturesque Elephant Gate (1899), the Egyptian Ostrich House (1901), the Indian Bison House (1905), the Russian Wisent House (1905), the Siamese Buffalo House (1907), and the Arabian style houses for solipeds (1910).The most remarkable example of the exotic style of zoo architecture was the Indian temple at Berlin Zoo or Elephantpagode. The magnificent elephant house was built in the form of a Hindu temple, with domes painted yellow, brown and blue. Huge columns supporting the roof have carved elephants' heads for capitals, and in the centre of the house stood the skeleton of a full-grown elephant. It was used for about 70 years until bombing during World War II destroyed it. The house for wading birds (i.e. cranes and storks) was based on Japanese architecture and stood from 1897 until 1943 when it was destroyed by the war. Also in the Japanese style, the entrance to the Berlin Zoo on Budapester Strasse is the reconstructed Elephant Gate of 1899 that was completely destroyed in the last war and resurrected in all its original detail in 1984.The Egyptian temple for ostriches opened its doors in 1901.  The ostrich house, based on Egyptian architecture, was decorated both inside and out with copies of Egytian murals, and on the back wall of the public area two immense figures, painted in a sitting position, were bathed in a deep and glorious sunset. It was destroyed during the war in 1943. Two other houses, the Russian blockhouse for European bison and the Indian blockhouse for American bison are still extant. Built in 1905 this Indo-Russian double blockhouse is home to the American bison on the one side and the Eurasian bison on the other. The American Bison House reminds visitors of a Canadian timber house. Its facade is ornamented with Native American paintings and totem poles of Pacific Northwest Indians are faithfully reproduced in front of the building. The house for the European bison was built like a Russian wooden manor house. The Berlin Zoo's Siamese Cattle House (1996) is the biggest Thai building in Europe.The new house, used for gaur and banteng, resembles an earlier (1907) one destroyed in World War II. An animal house in the Arab style, Persian tower stable, since 1910 is predominantly accommodation for equine species animals.
German merchant Carl Hagenbeck developed a new form of animal exhibition at the beginning of the twentieth century. When he opened his private owned zoo at Stellingen near Hamburg, (Tierpark Hagenbeck) in 1907, Hagenbeck had broken with a strong tradition to exhibit animals in accordance with taxonomy. He created a new style of exhibition based on ecological and geographical habitats including different species. Only two panoramas with moated exhibits existed originally: Africa and the Arctic. For example, the "Northern Panorama" exhibited seals and walruses in a pool in the foreground, with reindeer behind them, and polar bears behind the reindeer. In the "African Panorama", the foreground pond had ducks and flamingos; behind them were large plains with zebras, antelopes, and ostriches; behind them were lions and vultures at the foot of an artificial mountain, on which were ibex or barbary sheep. The different enclosures were divided with moats not visible to the public, and the successive enclosures were higher than the one in front. The exhibits were landscaped with plants and artificial rocks. The artist for the artificial rocks was Urs Eggenschwyler. Originally, the background consisted of artificial rockwork, supported on huge wooden scaffoldings. The surface was formed of cement moulded over metal gimmel-work, and arranged to form ledges and boulders, peaks and escarpments, and faced with coloured sand and paint. It was made sufficiently strong to bear the weight of the animals, which were confined within their bounds by undercut overhanging ridges, and by deep and wide ditches, masked by rockwork. This gave the public the impression they were seeing the animals together in one natural habitat. After initial skepticism, many zoological gardens throughout the world adopted Hagenbeck's ideas and replaced traditional enclosures. Edinburgh Zoo, for example, was one of these institutions inspired by Hagenbeck’s new design. Then there are the extraordinary artificial mountains of concrete, like the Mappin Terraces in London Zoo, designed in 1913-1914 by Peter Chalmers Mitchell and John James Joass.Eventually, whole zoos, such as those in Rome (1911), Munich (1928), Detroit (1928), and Vincennes (1934), followed Hagenbeck plans. Brookfield Zoo, opened in 1934, is known throughout the world for its extensive use of open-air, unbarred enclosures and natural barriers such as moats. In 1941 the African Plains exhibit, the first free-range, multispecies habitat, opened at the Bronx Zoo. The innovative, open habitat is a 4acres moated area featuring a savanna environment recreated for zebras, antelopes, and other grazing animals and birds, with lions kept apart on an island on the other side of a moat.Even if this kind of exhibiting animals to the public was revolutionary in the history and evolution of zoo design, the actual space provided to the animals remained relatively small and was, in fact, not different from that of the traditional enclosures. The new panoramas benefited the aesthetic sense of visitors and can be seen as mainly anthropocentric constructions.
At the beginning of the twentieth century, new approaches were also made to integrate modern style into zoo architecture.The Jugendstil buildings (1909-1912) at Budapest Zoo in Hungary were ornamented with carved animals. The Jugendstil pavilions of the Elephant House date of 1911 and were designed by Károly Kós.
During the 1930s, some attempts were made to introduce abstract design into the modern zoo architecture, like those famous abstract geometrical structures by Lubetkin in Regent's Park, Whipsnade and Dudley. London Zoo's Gorilla Pavilion was designed in 1932-1933 by the influential Tecton architectural firm, led by Russian emigre Berthold Lubetkin.The Round House is circular so that a half-drum shaped screen could be slid from within one half of it to enclose the other in cold weather, as a protection for the gorillas it was built to house.London Zoo's penguin exhibit designed in 1934 by Berthold Lubetkin and the Tecton Group was a icon of the Modern Movement with its sweeping, interlocking concrete ramps above the pool.
From the 1950s on, first attempts were made to integrate the behavioural needs of the animals into zoo design. This approach based on the ideas of Swiss zoologist Heini Hediger who published his book Wild Animals in Captivity in 1942, translated into English in 1950. In this work he gave cogent arguments for a biological and particularly behavioural approach to zoo design and animal care. But the attempts to integrate the knowledge about animal behaviour into zoo design were often ineffectual and not consequently implemented. More important than behaviour and welfare of the animals remained hygienic aspects and, above all, architectural innovation such as New Brutalism. The Elephant and Rhino Pavilion at London Zoo, designed by Hugh Casson and Neville Conder, and built 1962-1965, is such an example. Most enclosures constructed from the 1950s to the 1970s were sterile and small cages made of concrete or ceramic tiles. Meeting hygiene standards became important which resulted in enclosures resembling bathrooms. Few zoos adopted these techniques of "sanitary modernist" design more thoroughly than the one in America, Philadelphia Zoo which opened exhibits Carnivora House in 1951, Monkey House in 1958 and Rare Animal House in 1965. In 1963, the Tierpark Berlin-Friedrichsfelde opened the Alfred Brehm House for carnivores and tropical birds.This structure was for a long time the largest animal house in the world and the only one Cat House with indoor barless enclosures for lions and tigers. This structure houses a huge aviary containing many species of birds. The aviary is flanked by cages of wild cats and by terrariums of reptiles, and the whole is overgrown by exotic tropical vegetation. 
At the end of the twentieth century, new approaches were made to transform the appearance of hippopotamus exhibits. The so called "hippoquarium" is a term coined by the Toledo Zoo.The Toledo Zoo has an underwater hippo exhibit, but not the first or only one, the Sedgwick County Zoo (Kansas) built an underwater hippo viewing area in 1973. Opened in 1997, the new Hippopotamus House at Berlin Zoo is a hippopotamus aquarium, spanned by two fine-meshed glass domes where visitors can watch both above and underwater.
Due to limited space and a lack of financial means it still remains difficult to construct adequate enclosures, particularly for large animals and their requirement for a sizable territory. According to animal rights groups, zoos lacking the financial means or the interest in constructing more elaborate enclosures still keep their animals in inadequate conditions. These conditions can cause stereotypic behavior. Elephants in zoos can also often suffer from arthritis and foot disease. Only some zoological gardens are able to raise enough funds and have sufficient space to build more adequate enclosures for these animals. Such an example is urban Cologne Zoo, Germany, which opened in 2004 an indoor and outdoor elephant enclosure of about 5acres. Norman Foster's new addition to Copenhagen Zoo opened in June 2008 as an extension of Frederiksberg Gardens, the royal park in Copenhagen.The new Elephant House covers approximately 10% of the entire zoo site. At the end of 2001, the London Zoo's Asian elephants were moved from Regent's Park to Whipsnade Wild Animal Park in Bedfordshire, ending a 170-year tradition of keeping elephants at the city site. In the spring of 2003, the herd of five African elephants at Longleat Safari Park had been transferred from the Wiltshire park to a new purpose-built facility at the ZooParc de Beauval at St Aignan in France. In April 2005, the Detroit Zoo became the first U.S. zoo to give up its elephants on ethical grounds; the two Asian elephants were relocated to the Performing Animal Welfare Society (PAWS) Sanctuary in San Andreas, California. In 2006, three American zoos (Lion Country Safari, Philadelphia Zoo, Gladys Porter Zoo) announced the closure of their elephant exhibits due to a lack of space. Two other zoos, Bronx Zoo and Santa Barbara Zoo, announced the phase-out of their elephant exhibits.
During the 1980s many zoological gardens, first in the United States, changed their policy of designing animal enclosures. The so called "landscape immersion", a term coined by Seattle architect Grant Jones, transformed visibly the outlook and appearance of many zoos throughout the United States. The idea and concept of landscape immersion combines a naturalistic and realistic imitation of natural habitats with the environmental needs of the animals. It was developed by several landscape architects during the wholesale renovation of Woodland Park Zoo in Seattle in the late 1970s encouraged by zoo director David Hancocks. The first landscape immersion exhibit, an enclosure for gorillas, designed by Johnpaul Jones, opened in 1978 at Woodland Park Zoo. For the first time, zoo gorillas had trees to climb, places to hide, a complex landscape to explore, and live vegetation to interact with. According to the original idea and philosophy of landscape immersion the visitors are given the sense they were actually in the animals' habitat. Buildings and barriers are hidden and vegetation plays a dominant role. Urban zoos all over the USA initiated major new exhibits or renovations, or master plans. Following Woodland Park Zoo, Seattle; several zoos are notable in leading the way: Bronx Zoo, New York; Point Defiance Zoo, Tacoma, Washington; Atlanta Zoo (which became "Zoo Atlanta" after closing for a complete re-vamping); San Diego Zoo; Los Angeles Zoo; and Central Park Zoo (managed by the Bronx Zoo). The older zoos are reorganising their exhibits into bioclimatic or zoo-geographic themes. In New York City, at the Bronx Zoo, the Congo Gorilla Forest, a 6.5acres exhibit, which opened in July 1999, is the largest simulation of an African rainforest ever built. It is home to more than 300 animals, including the largest breeding group of lowland gorillas in North America. One of the best examples in Germany is the Erlebnis-Zoo Hannover ("adventure" Hanover Zoo), an EXPO 2000 project, now featuring six different zoo worlds.
Specific forms of exhibit that can also be referred to landscape immersion are walk-through enclosures and walk-in aviaries. A few European zoos had already realized such exhibits before the term landscape immersion was coined. These ideas were integrated into the concept of landscape immersion and consequently advanced. In contemporary zoos, there are a lot of walk-through exhibits where visitors enter enclosures of non-aggressive species, particularly for birds and small primates. Visitors are asked to keep to paths and avoid showing or eating foods that the animals might snatch. The animals are not tame. One example is Apenheul, a primate park opened in 1971 at Apeldoorn, Netherlands, where visitors can get into direct contact with squirrel monkeys and lemuridae on moated islands.
Associated with these changes of zoo design are large tropical indoor exhibits. Bronx Zoo’s 37000square feet Asian rainforest Jungle World, opened in 1985, is a pioneer exhibit of its kind. The exhibit is a mix of the real and artificial, in which live plants appear to be sprouting from vegetation sculpted from plastic, rubber, and epoxy.The display features more than 100 species of tropical plants, rocks and ledges crafted from concrete and fiberglass, and naturalistic murals merged with the terrain.It also features five waterfalls, numerous pools and streams, machine-made clouds, and background sounds that attempt to replicate the ambience of a real jungle. In Washington, D.C., the 12000square feet building Amazonia, opened in 1992, is a pioneer exhibit of a BioPark. The concept attempts to put animals in their appropriate context to explain the story of the ecosystem which includes human culture, animals, plants and the past.The centerpiece of the Amazonia exhibit is the Habitat, where visitors experience a replication of the sights, sounds and smells of a rainforest. The Lied Jungle at Omaha's Henry Doorly Zoo, opened in 1992, is said the largest indoor rainforest in the world; it occupies an 80feet tall building that spans 1.5acres. Zürich Zoo opened Masaola Hall in June 2003.The Madagascaran Rainforest Hall covers a space of 2.7acres where the public is able to walk and watch exotic species roaming within the hall.All the animals, lemurs, birds, fruit bats, reptiles, frogs, fish and insects are native to Madagascar and other Western Indian Ocean islands.With its dimensions of 90 m width, 120 m length and 30 m higth, this is one of the biggest artificial rainforests in the world. Leipzig Zoo, Germany, is currently building a similar, but larger project called Gondwanaland.
Burgers' Zoo at Arnhem, Netherlands, is known as presenting major indoor ecological displays.There are Burgers' Bush (1988), a tropical rainforest in a greenhouse of 3.7acres, the Mangrove Hall (1991), Burgers' Desert (1994), an American desert environment in a greenhouse of 1.85acres, and Burgers' Ocean (2000), displaying a representation of a coral sea in an aquarium containing 8 million liters of water.The Bush is 150 m long, 95 m wide and 20 m high. From the Bush, visitors have access to the Desert display by way of a long underground tunnel, as well as to the Ocean display.
The Desert Dome, an indoor display representing the desert, opened in April 2002 at Omaha's Henry Doorly Zoo, and the Kingdoms of the Night, a nocturnal animal exhibit, opened beneath the Desert Dome in April 2003.It is the world's largest glazed geodesic dome and both levels make up a combined total of 1.92acres.The Desert Dome has representations of geologic features from three deserts around the world: Namib Desert of south Africa; Red Center of Australia; and the Sonoran Desert of the southwest United States. The Kingdoms of the Night features a wet cave (with a 14abbr=onNaNabbr=on deep aquarium), a canyon, an African diorama, and representations of a Eucalyptus forest, a dry batcave, and a swamp.
The transformation of zoos to landscape immersion is slow and still in progress since the changes require financial and technical expenditures.In the United States alone, zoos claim to have spent over $1 billion during the 1990s on increasingly sophisticated exhibits, most notably so-called landscape immersion displays.
Special climate conditions are created for animals living in radical environments, such as penguins which are kept in refrigerated rooms.Special enclosures for reptiles, amphibians, insects, fish, and other aquatic life forms have also been developed.
London Zoological Gardens opened the first Reptile House (1849), the first public aquarium (1853), and the first Insect House (1881).There has been a "vivarium" at the London Zoo since 1849 when a reptile house was converted from the Cat House and was the first Reptile House to be established in the world.The world's first public aquarium, or Fish House as it was known for most of its innovative life, was opened in May 1853.The word "aquarium" also originates at London Zoo, beforehand the term for a fish enclosure was Aquatic Vivarium. What would today be called an insect or invertebrate house was opened in 1881 when a steel-and-glass structure usurped what had previously served as a refreshment room.
In the United States, zoos planners adopted a style of display in reptile houses similar to the habitat dioramas that had become popular in American natural history museums: they put the animals in glass-fronted cages, with foliage and a painted backdrop, arranged around the perimeter of an exhibition hall.Lighting the cages and keeping the hall dark, as in museums’ displays, reduced glare on the glass and focusing attention on the animals.Zoos that could afford to do so housed these small-scale natural settings in massive buildings -- museum like buildings that conveyed scientific and cultural authority.
The Reptile House at the Cincinnati Zoo is the oldest zoo building in America, dating from 1875.Crocodiles, snakes, turtles, frogs, and a reptile nursery are exhibited at the Bronx Zoo’s World of Reptiles in a historic building dating back to 1899.The St. Louis Zoo opened a reptile house in 1927. The facilities built specifically for snakes, lizards, frogs and other amphibians are inside a Mediterranean-style stucco building with a red tile roof. The National Zoo's Reptile House opened in 1931.The cages and public space were ventilated separately. In each glass-fronted cage, the vegetation, temperature, humidity, and light of its occupants' natural habitat have been simulated. In addition, the glass skylights permitted ultraviolet light to pass through, which was thought to be beneficial to reptiles.The exterior was designed as a red brick structure with dimensions of 200feet by 82feet.
In continental Europe, German-speaking zoos planners associated aquaria and vivaria sections in the same special building differently called Aquarium, Exotarium, or Vivarium.
In 1910, the old Berlin Aquarium, founded by Alfred Brehm, closed and Berlin Zoo shareholders' association decided a new aquarium should be built at the Berlin Zoo.The new building, planned by Oskar Heinroth and opened in 1913, was to be much more than just an aquarium. Its three storeys were home to sweetwater and saltwater fish, reptiles, amphibians, and a large number of invertebrates.On the first floor was an aquarium, on the second a terrarium, and on the third an insectarium.Inside was created the first walkthrough enclosure in the center of the aquarium. This large hall for crocodiles extended up through the three floors.From the aquarium floor the crocodiles could be seen swimming underwater through large windows. On the second floor a bridge led through a tropical river exhibit with sandbanks where the crocodiles lived. And from the third floor the exhibit could be seen into the glasshouse from above.The aquarium was destroyed in 1943 during World War II, but the building was restored with its original floor plan through the 1950s.
The Frankfurt Zoo aquarium inaugurated in 1928 was destroyed in 1944 during World War II. It was reopened in 1957 and substantially enlarged. It became the Exotarium where climatic landscapes and endangered reptiles can also be seen.A hall of climatic landscapes was added, featuring a tropical riverbank with birds, reptiles, and fish. In a polar landscape, where cooling units produced artificial ice and bacteria filters cleaned the air, seals and penguins could be seen through underwater windows.At the aquarium section, 14 large tanks were arranged in geographic order to show, for example, South Sea reefs, a Black Forest river, and Amazon's dark water streams.In the reptile hall, where visitors walked through vegetation, glass roofs could be moved to allow direct sunlight to reach the animals, and in the crocodile area a tropical thunderstorm was presented daily.
In the Basel Zoo, there is a large Vivarium (“Aquarium”/“Terrarium”) with freshwater and marine species of fish and invertebrates, penguins, reptiles and a few amphibians.Basel Zoo's Vivarium opened its doors in 1972 and represented already by its structural concept a characteristic. The "vivarium" offers an interactive tour of the world depicting the story of evolution on earth. The 350 meters long visitor course leads first under the surface of the pond and penetrates always far into the depth of the oceans and the evolution following again up to the country. Unnoticed the visitor on its way turned around 360 degrees. 
Zoos may have nocturnal houses, special buildings designed for nocturnal animals, with dim white or red lighting used during the day, so the animals will be active when visitors are there, and brighter lights at night to help them sleep.These exhibits reverse day and night so that visitors can see in human daylight hours some of the activities of the animal world that moves mostly after dark.The exhibits inside invert the life cycle of the animals by using strong artificial light during exterior darkness, and red light, which is invisible to most nocturnal animals, during human daylight. Thus they and their lifestyle can be observed.
The Bristol Zoo developed the first example of a nocturnal house with reverse lighting in 1953.The phenomenon was soon reproduced in zoos all over the world. The Antwerp Zoo's Nocturama had been opened for the creatures of the night in 1968.The Bronx Zoo’s World of Darkness, a building exhibiting nocturnal reptiles, birds and mammals, opened in 1969.
The Grzimek House for Small Mammals at Frankfurt Zoo is famous for its nocturnal displays.This big structure was the 16150square feet Grzimekhaus opened in 1978, a three-level building located to a great extend underground. It was the first specially constructed house of this dimensions, and is still one of the largest, most modern, and most complicated constructions of its kind. Some 50 artificial habitats accommodate some of the rarest animals.The building was divided into two sections. Half of the house is a nocturnal section, where the light regime has been reversed to present nocturnal animals during their activity phase. The other half is a daylight section for diurnal animals.
The nocturnal exhibit concept exists also in a new form such as a walk-through approach.An example is Amersfoort Zoo, Netherlands, where a walk-through nocturnal exhibit opened in 2003.
Some accredited U.S. zoos are private, for-profit entreprises.
Other accredited U.S. zoos are in the public sector, customarily part of a park district for budgetary purposes. Most of these have a private support group, a zoological or aquarium society, that provide supplementary funds.Although they can be characterized as "public", this merely describes features such as ownership or primary source of funds. There are no substantive differences between the goals or operations of public and private nonprofit zoos and aquariums.
Many cities across the country have shifted their zoos from municipal management to nonprofit management (even as they retain ownership of the land and the zoo facilities). This shift, usually to a "Friends of the Zoo" association, allows the city to shift responsability for zoo staffing to a nonprofit with much more flexible hiring rules.Typically, the relation between the society and the city is in the form of a complicated contractual agreement that specifies the extent of continuing city subsidy as well as the nonprofit organization's financial and management responsibility.
Related and similar institutions in aims, staff and history are public aquaria. At the time when the first zoological gardens were established during the nineteenth century also public aquaria came into existence. Today, both zoos and public aquaria are integrated in the same national and international umbrella organizations. These zoo associations proclaim to force their members to achieve certain standards in animal management, veterinary care, aims, and stewardship.
The International Species Information System (ISIS), a computer-based inventory system, was established in 1973 to facilitate collection and population management for wild animals maintained in captivity.
Most zoological gardens incorporated within international umbrella organizations are led by professionals such as zoologists or veterinarians.Typical departments and subdepartments include the animal collection with live mammal, bird, reptile and amphibian, fish and invertebrate inventories.
Curators plan for the development, maintenance, and growth of the animal collection and animal care staff.They are responsible for the acquisition of animals and play a role in the administration of captive breeding programs. They also participate in scientific conferences, write scientific papers, or assist in exhibit design.
Veterinarians provide medical care for ill or injured animals including surgery, vaccinations and physical exams.They also develop and implement preventive health care, or help determine healthful animal diets.
Responsible for the actual care of the animals within these institutions are zookeepers.The training of a zookeeper is very broad and covers many areas of modern animal husbandry, basic veterinary knowledge, behavioural biology knowledge. Daily basic duties of zoo keepers include cleaning and maintenance of animal enclosures and feeding of the animals.Some zookeepers prepare animal diets, report and record animal's health and behaviour, or assist veterinarians.The educational requirements for an entry level zoo keeper vary but are often a college degree in zoology, biology or an animal-related field. Some colleges offer programs oriented towards a career in zoos. Job advancement is also possible but more limited than in some other careers requiring a college degree. Some zoos, particularly roadside zoos, are private-owned amateur facilities with a lack of well trained personnel.
The organisation of animal care staff depends on zoo architecture and enclosure design.
Traditionally, the live exhibits were often organized by taxonomy, resulting in clusters of carnivores cages, bird aviaries, primate exhibits, and so on, which led to sections within a zoo cared for by specialized staff.Some keepers can become highly specialized such as those who concentrate on a specific group of animals like birds, great apes, elephants or reptiles.
Modern habitat exhibits attempt to display a diversity of species of different animal classes within one enclosure to represent ecosystem concepts. Groups of enclosures are organized by themes, relating to, for example, zoogeography and bioclimatic zones, rather than taxonomy.The shift in exhibit arrangements is changing the scope of work for curatorial staff and animal keepers, as they become habitat keepers, with a necessary working knowledge of living environment care, including landscape maintenance, plant care, climate control, and expanded knowledge of animals husbandry for many more species across taxonomic classes.
The physical health as well as the social and behavioral well-being of zoo animals depends on enclosure design, nutrition, husbandry, management practices, group social structure, behavioral enrichment, preventive medicine, and medical and surgical care.
Within the twentieth century great strides had been made in the development of management methods and of principles and techniques relating to the maintenance of captive populations that increasingly satisfied the physical and psychological needs of the animals.
Proper feeding management of wild animals in captivity incorporates both husbandry skills and applied nutritional sciences. As a basic foundation of animal management, nutrition is integral to longevity, disease prevention, growth and reproduction.
Most contemporary zoos led by professionals are aware of environmental enrichment, also called behavioral enrichment, as a part of the daily care of animals. Environmental enrichment refers to the practice of providing animals with environmental stimuli. The goal of environmental enrichment is to improve an animal's quality of life by increasing physical activity, stimulating natural behaviors, and preventing or reducing stereotypical behaviors.
The use of behavioral training has often allowed zoos to improve dramatically their ability to care for animals, while reducing animal stress and increasing safety for both keeper and animal during care procedures.
But sometimes even those zoos proclaiming high standards can fail to meet them in some way. Accidental deaths during the six months of animal stocking preceding the opening of Disney's Animal Kingdom were investigated by the United States Department of Agriculture (USDA) in 1998. After a series of publicized animal deaths at the National Zoo in early 2003, the National Academies released an interim report in 2004 and a final report in 2005. Another example is the captive breeding management of great apes where these animals and their infants are traded and shuttled from place to place.
Because they wanted to stress conservation issues, many large zoos stopped the practice of having animals perform tricks for visitors. The Detroit Zoo, for example, stopped its elephant show in 1969, and its chimpanzee show in 1983, acknowledging that the trainers had probably abused the animals to get them to perform.
Some zoo practices in countries without animal protection laws would be illegal in many countries. Some examples include in 2008 the practices of Chinese zoos:
At the beginning of the twentieth century, animals were caught in the wild; at the end of the twentieth century, many species were bred in zoos using sophisticated, and expensive, scientific procedures. For example, in 1910, the Bronx Zoo exhibited 1,160 species but recorded only 86 births. In 1993, it had 633 species and 1,253 births. Nearly 90% of the mammals and 70% of the birds in a modern zoo collection were at the mid-nineties bred in captivity under careful management schemes that seek to avoid inbreeding.
The World Zoo Conservation Strategy published in 1993 stated "that the commercial wild animal trade as a source of zoo animals should cease as soon as possible. Such animals as must be collected from the wild, must be collected for specific educational and conservation purposes. They should not be chosen from dealers’ lists of animals randomly collected for commercial purposes." These goals, while closer than in 1993, are still valid in The World Zoo and Aquarium Conservation Strategy published in 2005.
It is general practice for zoos to obtain animals from each other, usually by exchange, as loans or gifts, and in some countries, when rescued from unsuitable circumstances. 
Controversy surrounded the importation of seven African elephants (an officially endangered species) from the wilds of Swaziland to the San Diego Wild Animal Park in 2003, despite offers to move the elephants to reserves elsewhere in Africa. Prior to the import, three resident elephants were shipped to Chicago's Lincoln Park Zoo, where all three elephants died within two years.  There have been births from the Swaziland elephants since coming to the San Diego Wild Animal Park. As of 2008, the San Diego Wild Animal Park housed eleven African elephants in a 3acres enclosure. 
The downside to breeding the animals in captivity is that thousands of them are placed on "surplus lists", and sometimes sold to circuses, animal merchants, auctions, pet owners, and game farms. The San Jose Mercury News conducted a two-year study that suggested of the 19,361 mammals who left accredited zoos in the United States between 1992 and 1998, 7,420 (38 percent) went to dealers, auctions, hunting ranches, unaccredited zoos and individuals, and game farms. Some zoos have advertised surplus animals in the Animal Finders' Guide, a newsletter in which the owners of hunting ranches post notices of sales and auctions.
A German Greens Party politician alleged in March 2008 that hundreds of the Berlin Zoo's 23,000 animals are missing, amid allegations that they have been slaughtered, and that some tigers and leopards were sent to China to make drugs for traditional Chinese medicine. The Director of the zoo replied by saying he believes his detractors are spreading "untruths, half-truths and lies".
Many countries have legislation to regulate zoos that requires these institutions to be licensed and inspected.Zoo regulation is usually supported by written standards relating to species, exhibits and management.
In the United States, any public animal exhibit must be licensed and inspected by the United States Department of Agriculture, United States Environmental Protection Agency, Drug Enforcement Agency, Occupational Safety and Health Administration, and others. Depending on the animals they exhibit, the activities of zoos are regulated by laws including the Endangered Species Act, the Animal Welfare Act, the Migratory Bird Treaty Act of 1918 and others. Additionally, zoos in North America may choose to pursue accreditation by the Association of Zoos and Aquariums (AZA). To achieve accreditation, a zoo must pass an application and inspection process and meet or exceed the AZA's standards for animal health and welfare, fundraising, zoo staffing, and involvement in global conservation efforts. Inspection is performed by three experts (typically one veterinarian, one expert in animal care, and one expert in zoo management and operations) and then reviewed by a panel of twelve experts before accreditation is awarded. This accreditation process is repeated once every five years. The AZA estimates that there are approximately 2,400 animal exhibits operating under USDA license as of February 2007; fewer than 10% are accredited.
In April 1999, the European Union introduced a directive to strengthen the conservation role of zoos, making it a statutory requirement that they participate in conservation and education, and requiring all member states to set up systems for their licensing and inspection.Zoos are regulated in the United Kingdom by the Zoo Licensing Act of 1981, which came into force in 1984. The act requires that all zoos be inspected and licensed, and that animals kept in enclosures are provided with a suitable environment in which they can express normal behavior.
Hancocks, David, "Is There a Place in the World For Zoos?", pp.137-144; Farinato, Richard, "Another View of Zoos", pp.145-147.