Island tameness is the tendency of many populations and

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of animals living on isolated

island An island or isle is a piece of land, distinct from a continent, completely surrounded by water. There are continental islands, which were formed by being split from a continent by plate tectonics, and oceanic islands, which have never been ...

s to lose their wariness of potential

predators Predation is a biological interaction in which 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 ...

, 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 p ...

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

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

Hawaiian Islands The Hawaiian Islands () are an archipelago of eight major volcanic islands, several atolls, and numerous smaller islets in the Pacific Ocean, North Pacific Ocean, extending some from the Hawaii (island), island of Hawaii in the south to nort ...

. The most famous example is the

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

, which owed its

extinction Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

in large part to a lack of fear of humans, and many species of

penguin Penguins are a group of aquatic flightless birds from the family Spheniscidae () of the order Sphenisciformes (). They live almost exclusively in the Southern Hemisphere. Only one species, the Galápagos penguin, is equatorial, with a sm ...

(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 Lizard is the common name used for all squamate reptiles other than snakes (and to a lesser extent amphisbaenians), encompassing over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The ...

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 author

Charles Darwin Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English Natural history#Before 1900, naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all speci ...

, he believed that escape behavior evolved to be lower where

predator Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation ...

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 natural science of the relationships among living organisms and their environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere levels. Ecology overlaps with the closely re ...

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

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 Northwestern Hawaiian Islands, Northwest Hawaiian Island of Laysan. This small island was and still is an important seabird colony, and sustained a num ...

and

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

) and continues to threaten others, such as the

Key deer The Key deer (''Odocoileus virginianus clavium'') is an endangered subspecies of the white-tailed deer that lives only in the Florida Keys. It is the smallest extant North American deer species. Description This deer can be recognized by its ch ...

. The only conservation 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 () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

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 the eukaryotes that form the Kingdom (biology), kingdom Plantae; they are predominantly Photosynthesis, photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with c ...

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.

See also

References

Further reading