Acclimatisation societies were voluntary associations in the 19th and 20th centuries that encouraged the introduction of non-native species in various places around the world with the hope of their acclimatisation and adaptation. The motivation at the time was a sense that introducing these species of plants and animals would enrich the flora and fauna of a region. These societies were born during a period of colonialism when Europeans began to settle in unfamiliar environments, and the movement sought to establish familiar plants and animals (mainly from Europe) in new areas while also bringing exotic and useful foreign plants and animals into the European centres. Today it is widely understood that introducing species can be harmful to native species and their ecosystems; for example, in Australia plants were harmed by rabbits' overgrazing; in North America house sparrows displace and kill native birds; and around the world, salamander populations are today threatened by introduced fungal infections. At the time of acclimatisation societies, however, this was insufficiently understood.
A definition of acclimatisation was attempted by Alfred Russel Wallace in his entry in the 11th edition of the Encyclopædia Britannica (1911). Here Wallace tried to differentiate the idea from other terms like domestication and naturalization. He noted that a domesticated animal could live in environments controlled by humans. Naturalization, he suggested included the process of acclimatization which involved "gradual adjustment". The idea, at least in France, was associated with Lamarckism and Wallace noted that there were some like Charles Darwin who denied the possibility of forcing individual animals to adjust. Wallace however pointed out that there was the possibility that there were variations among individuals and that some could have the ability to adapt to new environments.
The first Acclimatisation society was La Societé Zoologique d'Acclimatation founded in Paris on 10 May 1854 by Isidore Geoffroy Saint-Hilaire. It was essentially an offshoot of the Paris museum of natural history and the other staff included de Bréau, Antoine César Becquerel and his son Alexandre. Saint-Hilaire believed in the Lamarckian idea that humans and animals could be forced to adapt to new environments. The Paris society established a branch in Algeria as well as the Jardin d' Acclimatation in Paris in 1861 to showcase not just new animals and plants but also people from other lands. Rewards in the form of medals were offered for anyone in the colonies to establish breeding animals. The rules were that at least six specimens had to be maintained with at least two instances of breeding in captivity. After Saint-Hilaire's death in 1861 the Society was headed by Édouard Drouyn de Lhuys, foreign minister to Napoleon III and many of the functionaries were diplomats who established ties with officers in the colonies both French and foreign. Franco-British as well as Franco-Australian ties were involved in the movements of plants and animals. Australian acacias for instance were introduced in Algeria by the French and by the British in South Africa. François Laporte, naturalist and consul in Melbourne and Ferdinand von Mueller of the Acclimatisation Society of Victoria were involved in the transfer of many plant species out of Australia. In some cases these movements were not direct but via Paris and Kew.
The British acclimatisation society originated from an idea proposed by the management of The Field journal. A meeting was held on January 21, 1859, at the London Tavern on Bishopsgate Street. The attendees included Professor Richard Owen at the head of the table and the servings included a large pike, American partridges, a young bean goose and an African eland. At the meeting Mitchell and others suggested that many of these exotic animals could live in the British wilderness. Professor Owen wrote in the newspapers later on the taste of the eland and the need for animal introductions. On June 26, 1860, another meeting was held and the Acclimatisation Society was formally founded in London and a year later the Secretary to the Society, Frank Buckland, a popular naturalist known for his taste in exotic meats, noted the "success" of the Society in introducing peafowl, common pheasant, swan, starling and linnet into Australia through the efforts of Edward Wilson. One of the supporters of the Society was Miss Burdett Coutts. Other such societies spread quickly around the world, particularly to European colonies in the Americas, Australia and New Zealand. In many instances they existed both as societies for the study of natural history as well as to improve the success rate of introduced species. In 1850, English sparrows were introduced into America and Eugene Schieffelin introduced starlings in 1890 as part of a plan to introduce all the birds mentioned in Shakespeare.
The appeal of acclimatisation societies in colonies, particularly Australia and New Zealand, was the belief that the local fauna was in some way deficient or impoverished; there was also an element of nostalgia in colonists who desired to see familiar species. An Australian settler, J. Martin, complained in 1830 that the "trees retained their leaves and shed their bark instead, the swans were black, the eagles white, the bees were stingless, some mammals had pockets, others laid eggs, it was warmest on the hills..." It was here that the desire to make the land feel more like England was strongest. The Acclimatisation Society of Victoria was established in 1861. Speaking at the Society, George Bennett pointed out how it was important to have such an organisation, citing the example of the Earl of Knowsley who had been conducting successful experiments in private whose results had been lost with his death. A major proponent of importing and exporting trees and plants was Ferdinand von Mueller. Introductions of commercially valuable species or game species were also made. In some instances the results were disastrous, such as the economic and ecological effects of introducing rabbits to Australia or possums to New Zealand. The disastrous effects were rapidly felt and a Rabbit Nuisance Act was passed in 1876 in New Zealand. To make matters worse, the suggestion was made that weasels and stoats could control the rabbits. Despite warnings from Alfred Newton and others, these predators were introduced and Herbert Guthrie-Smith declared it as an "attempt to correct a blunder by a crime."
In 1893, T.S. Palmer of California wrote on the dangers of animal introduction. In 1906, the editors of the Avicultural Magazine were decidedly against the idea of bird introductions. The emergence of the field of ecology transformed expert and public opinion on introductions and gave way to new rules. Quarantine regulations began to be set up instead. Beginning in New Zealand, some of the acclimatisation societies transformed themselves into fish and game organizations.