People have always kept captive wildlife. Nomadic peoples maintained few species, but with the emergence of sedentary societies, animal collections became larger and more commonplace, e.g., in Egypt, Assyria and China 3000-1000 BCE, and later in Greece and Rome. Augustus Caesar (63 BCE–14 CE) maintained a menagerie of over 3,500 vertebrate animals — a collection larger than any Canadian zoo. The famous menagerie of the Aztec ruler Montezuma II (circa 1480–1520 CE) employed 600 keepers. When monarchies were replaced by parliamentary governments, many private collections became public zoos. For example, the menagerie of Louis XVI, at Versailles, was moved to the Jardin des Plantes (1794).
Private zoos brought prestige and enjoyment to their owners and entertainment to their guests. Early public zoos emphasized recreation, later coming to serve modern objectives of education, conservation and research. During the first half of the 20th century, zoos commonly attempted to show a wide variety of species in rows of cages, giving animal inventories the character of stamp collections. The concentration of species offered a broad spectrum for taxonomic study and, by its diversity, considerable entertainment to viewers. However, the approach has become outdated. Zoos have been redesigned on foundations of a better understanding of animal psychology, behaviour and wildlife appreciation. Zoo education programs have shifted focus to enhance ecosystem, biodiversity and environmental awareness.
The artificial environment of a zoo must accommodate the physical and psychological needs of animals. Exhibits must provide seclusion, sight barriers, camouflage, opportunities for hierarchical positioning, and stimulus to prevent boredom and stereotyped behaviour. The reduction of obvious barriers (e.g., bars, fences) is important. Many modern exhibits contain animals through their physical and behavioural limitations, using water moats, dry moats, electric fences, light zones, etc. Glass barriers are used to provide an unobstructed view.
Zoos also include off-exhibit facilities (e.g., maternity dens, sleeping boxes, treatment enclosures) that are often equipped with closed-circuit television for behavioural monitoring.
Zoos are engaged in various international conservation programs. Zoos have become wildlife producers, not wildlife users as in former times. Today, few animals are collected from the wild for zoos. Most zoos operate extensive rescue and animal orphanage programs. Rehabilitated specimens are returned to their native habitats or are exhibited and traded with other zoos.
With diminishing wild habitats, countless species of animals become endangered, even extinct. Zoos propagate various species in captivity, and some species now depend on captive management for survival. Relatively few species can be perpetuated in captivity: only about 9 per cent of known mammal species have had consistent multiple-generation reproductions in captivity. The Calgary Zoo and the Toronto Zoo established ex situ breeding programs for whooping cranes (Calgary) and black-footed ferrets (Toronto) as an integral part of the species recovery programs of the Canadian Wildlife Service of the US Department of the Interior. The zoos are propagating animals to protect the gene pool and enable in situ re-introduction.
Objectives are now focused on general conservation, establishment of self-sustaining populations, specialized education programs and presentation of wildlife in natural habitat settings.
Zoos have become complex operations. Animal husbandry, research and development, education and interpretation, veterinary medicine, public relations, fund development, food services, horticulture, facility maintenance, security, marketing, general administration and finance have important zoo components. Many zoos are subsidized by municipal or provincial funding; direct federal funding is less common. Other facilities operate commercially; shareholders receive profits after operating expenses and capital development costs are covered. Commonly, zoos have the support of zoological societies. These societies are typically volunteer, usually tax-exempt, non-profit organizations; involvement ranges from interested affiliation to managing authority.
Zoos in Canada
Major zoos are found in larger cities. Andrew Downs’ Zoological Garden in Halifax (1847–67; 1869–72) was Canada’s first. The Riverdale Zoo in Toronto (1887–1974) followed. The Toronto Zoo, Canada's largest, opened in 1974. Others include Assiniboine Park Zoo, Winnipeg (1905); Calgary Zoo (1917); Provincial Wildlife Park, Shubenacadie, Nova Scotia (1947); Vancouver Aquarium (1956); Edmonton Valley Zoo (1959); Aquarium du Québec (1959); African Lion Safari, Rockton, Ontario (1969); Parc Safari, Hemmingford, Quebec (1972); Salmonier Nature Park, near Holyrood, Newfoundland (1978); and Ripley’s Aquarium of Canada, Toronto (2013).
Canadian zoos that are now closed include Stanley Park Zoo, Vancouver (1888–1997); Moose Jaw Wild Animal Park (1929–1995); Jardin Zoologique de Montréal (1957–2008); and Aquarium de Montréal, 1967–1991);
Canadian zoos range from very modest collections to facilities exhibiting more than 3,000 animals of over 400 species (invertebrates excluded). Costly housing requirements during the winter season may limit the number of tropical species.