Island tameness is the tendency of many populations and

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of animals living on isolated

island An island (or isle) is an isolated piece of habitat that is surrounded by a dramatically different habitat, such as water. Very small islands such as emergent land features on atolls can be called islets, skerries, cays or keys. An island ...

s to lose their wariness of potential

predators Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

, particularly of large animals. The term is partly synonymous with ecological naïveté, which also has a wider meaning referring to the loss of defensive behaviors and

adaptation In biology, adaptation has three related meanings. Firstly, it is the dynamic evolutionary process of natural selection that fits organisms to their environment, enhancing their evolutionary fitness. Secondly, it is a state reached by the po ...

s needed to deal with these "new" predators. Species retain such wariness of predators that exist in their environment; for example, a

Hawaiian goose The nene (''Branta sandvicensis''), also known as the nēnē or the Hawaiian goose, is a species of bird Endemism in birds, endemic to the Hawaiian Islands. The nene is exclusively found in the wild on the islands of Oahu, Maui, Kauai, Kauai, Mo ...

retains its wariness of hawks (due to its main predator being the

Hawaiian hawk The Hawaiian hawk or ''io'' (''Buteo solitarius'') is a raptor in the genus '' Buteo'' endemic to Hawaii, currently restricted to the Big Island. The ''io'' is one of two extant birds of prey that are native to Hawaii, the other being the ''pueo' ...

), but does not exhibit such behaviors with mammals or other predators not found on the

Hawaiian Islands The Hawaiian Islands ( haw, Nā Mokupuni o Hawai‘i) are an archipelago of eight major islands, several atolls, and numerous smaller islets in the North Pacific Ocean, extending some from the island of Hawaii in the south to northernmost Kur ...

. The most famous example is that of the

dodo The dodo (''Raphus cucullatus'') is an extinct flightless bird that was endemic to the island of Mauritius, which is east of Madagascar in the Indian Ocean. The dodo's closest genetic relative was the also-extinct Rodrigues solitaire. The ...

, which owed its extinction in a large part to a lack of fear of humans, and many species of

penguin Penguins (order (biology), order List of Sphenisciformes by population, Sphenisciformes , family (biology), family Spheniscidae ) are a group of Water bird, aquatic flightless birds. They live almost exclusively in the Southern Hemisphere: on ...

(which, although wary of sea predators, have no real land predators and therefore are very bold and curious towards humans). A comparison of 66 species of lizards found that flight initiation distance (how close a lizard allows a human "predator" to approach before it flees) decreases as distance from the mainland increases and is shorter in island than in mainland populations. According to the authors,

Charles Darwin Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all species of life have descended fr ...

believed that escape behavior evolved to be lower where

predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

s were rare or absent on remote islands because unnecessary escape responses are costly in terms of time and energy. Island tameness can be highly maladaptive in situations where humans have introduced predators, intentionally or accidentally, such as dogs, cats, pigs or rats, to islands where

ecologically Ecology () is the study of the relationships between living organisms, including humans, and their biophysical environment, physical environment. Ecology considers organisms at the individual, population, community (ecology), community, ecosy ...

naïve fauna lives. It has also made many island species, such as the extinct dodo or the

short-tailed albatross The short-tailed albatross or Steller's albatross (''Phoebastria albatrus'') is a large rare seabird from the North Pacific. Although related to the other North Pacific albatrosses, it also exhibits behavioural and morphological links to the alb ...

, vulnerable to human hunting. In many instances the native species are unable to learn to avoid new predators, or change their behavior to minimize their risk. This tameness is eventually lost or reduced in some species, but many island populations are too small or breed too slowly for the affected species to adapt quickly enough. When combined with other threats, such as habitat loss, this has led to the extinction of many species (such as the

Laysan rail The Laysan rail or Laysan crake (''Zapornia palmeri'') was a flightless bird endemic to the Northwest Hawaiian Island of Laysan. This small island was and still is an important seabird colony, and sustained a number of endemic species, includ ...

and

Lyall's wren Lyall's wren or the Stephens Island wren (''Traversia lyalli'') is a small, extinct, flightless passerine belonging to the family Acanthisittidae, the New Zealand wrens. It was once found throughout New Zealand, but when it came to the attention ...

) and continues to threaten others, such as the

Key deer The Key deer (''Odocoileus virginianus clavium'') is an endangered deer that lives only in the Florida Keys. It is a subspecies of the white-tailed deer (''O. virginianus''). It is the smallest extant North American deer species. Description Th ...

. The only

conservation Conservation is the preservation or efficient use of resources, or the conservation of various quantities under physical laws. Conservation may also refer to: Environment and natural resources * Nature conservation, the protection and managem ...

techniques that can help endangered species threatened by novel introduced species are creating barriers to exclude predators or eradicating those species.

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

has pioneered the use of offshore islands free of introduced species to serve as wildlife refuges for ecologically naïve species. A comparable phenomenon may be present in

plant Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclud ...

species that colonize faraway islands devoid of their natural predators on the mainland, losing anti-browsing measures (like spines and toxins). However, this point is in need of further study.Burns, Kevin C. (2019). ''Evolution in Isolation: The Search for an Island Syndrome in Plants''. Cambridge University Press.

References

{{reflist Behavioral ecology

Tameness A tame animal is an animal that is relatively tolerant of human presence. Tameness may arise naturally (as in the case, for example, of island tameness) or due to the deliberate, human-directed process of training an animal against its initially ...

See also

Further reading

References