Vagrancy (biology)
Encyclopedia
Vagrancy is a phenomenon in biology
whereby individual animals appear well outside their normal range
; individual animals which exhibit vagrancy are known as vagrants. The term accidental is sometimes also used. There are a number of factors which might cause an individual to become a vagrant — genetic factors and weather conditions are two — but the causes are overall poorly understood. Vagrancy can be a precursor to colonisation
if individuals survive.
Vagrancy is known to occur in bird
s, insect
s, mammal
s and turtle
s.
In autumn, some young birds, instead of heading to their usual wintering grounds, take "incorrect" courses and migrate through areas which are not on their normal migration path. For example Siberian passerine
s which normally winter in Southeast Asia
are commonly found in Northwest Europe, e.g. Arctic Warbler
s in Britain. This is reverse migration
, where the birds migrate in the opposite direction to that expected (say, flying north-west instead of south-east). The causes of this are unknown, but genetic mutation or other anomalies relating to the bird's magnetic sensibilities is suspected.
Other birds are sent off course by storms, such as North America
n birds, blown across the Atlantic Ocean
to Europe
. Birds can also be blown out to sea, become physically exhausted, land on a ship and end up being carried across the ocean.
, and dragonflies.
s, seals
, and kangaroo
s.
s, snakes (e.g. Pelamis platurus ), crocodilians, and probably also occurs in lizards. It therefore seems to be a fairly widespread phenomenon in reptiles. Saltwater crocodiles are especially prone to vagrancy, with individuals occasionally being recorded in odd locales including Fiji
, Iwo Jima
, and even the Sea of Japan
.
Biology
Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy. Biology is a vast subject containing many subdivisions, topics, and disciplines...
whereby individual animals appear well outside their normal range
Range (biology)
In biology, the range or distribution of a species is the geographical area within which that species can be found. Within that range, dispersion is variation in local density.The term is often qualified:...
; individual animals which exhibit vagrancy are known as vagrants. The term accidental is sometimes also used. There are a number of factors which might cause an individual to become a vagrant — genetic factors and weather conditions are two — but the causes are overall poorly understood. Vagrancy can be a precursor to colonisation
Colonisation (biology)
Colonisation is the process in biology by which a species spreads into new areas, regions, and continents. It is sometimes also referred to as immigration, but colonisation often refers to successful immigration with integration to a community, having resisted initial local extinction.One classic...
if individuals survive.
Vagrancy is known to occur in bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s, insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s, mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s and turtle
Turtle
Turtles are reptiles of the order Testudines , characterised by a special bony or cartilaginous shell developed from their ribs that acts as a shield...
s.
In birds
In the northern hemisphere, adult birds (possibly inexperienced younger adults) of many species are known to continue past their normal breeding range during their spring migration and end up in areas further north (such birds are termed spring overshoots.)In autumn, some young birds, instead of heading to their usual wintering grounds, take "incorrect" courses and migrate through areas which are not on their normal migration path. For example Siberian passerine
Passerine
A passerine is a bird of the order Passeriformes, which includes more than half of all bird species. Sometimes known as perching birds or, less accurately, as songbirds, the passerines form one of the most diverse terrestrial vertebrate orders: with over 5,000 identified species, it has roughly...
s which normally winter in Southeast Asia
Southeast Asia
Southeast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...
are commonly found in Northwest Europe, e.g. Arctic Warbler
Arctic Warbler
The Arctic Warbler, Phylloscopus borealis, is a widespread leaf warbler in birch or mixed birch forest near water throughout its breeding range in Fennoscandia and northern Asia. It has established a foothold in North America, breeding in Alaska. This warbler is strongly migratory; the entire...
s in Britain. This is reverse migration
Reverse migration
Reverse migration is a phenomenon in bird migration. Although some large birds such as swans learn migration routes from their parents, in most small species, such as passerines, the route is genetically programmed, and young birds can innately navigate to their wintering area.Sometimes this...
, where the birds migrate in the opposite direction to that expected (say, flying north-west instead of south-east). The causes of this are unknown, but genetic mutation or other anomalies relating to the bird's magnetic sensibilities is suspected.
Other birds are sent off course by storms, such as North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
n birds, blown across the Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
to Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
. Birds can also be blown out to sea, become physically exhausted, land on a ship and end up being carried across the ocean.
In insects
Vagrancy in insects is recorded from many groups — it is particularly well-studied in butterflies and mothsMoths
Moths may refer to:* Gustav Moths , German rower* The Moths!, an English indie rock band* MOTHS, members of the Memorable Order of Tin Hats...
, and dragonflies.
In mammals
In mammals, vagrancy has been recorded for batBat
Bats are mammals of the order Chiroptera "hand" and pteron "wing") whose forelimbs form webbed wings, making them the only mammals naturally capable of true and sustained flight. By contrast, other mammals said to fly, such as flying squirrels, gliding possums, and colugos, glide rather than fly,...
s, seals
Pinniped
Pinnipeds or fin-footed mammals are a widely distributed and diverse group of semiaquatic marine mammals comprising the families Odobenidae , Otariidae , and Phocidae .-Overview: Pinnipeds are typically sleek-bodied and barrel-shaped...
, and kangaroo
Kangaroo
A kangaroo is a marsupial from the family Macropodidae . In common use the term is used to describe the largest species from this family, especially those of the genus Macropus, Red Kangaroo, Antilopine Kangaroo, Eastern Grey Kangaroo and Western Grey Kangaroo. Kangaroos are endemic to the country...
s.
In reptiles
Vagrancy has been recorded for turtleTurtle
Turtles are reptiles of the order Testudines , characterised by a special bony or cartilaginous shell developed from their ribs that acts as a shield...
s, snakes (e.g. Pelamis platurus ), crocodilians, and probably also occurs in lizards. It therefore seems to be a fairly widespread phenomenon in reptiles. Saltwater crocodiles are especially prone to vagrancy, with individuals occasionally being recorded in odd locales including Fiji
Fiji
Fiji , officially the Republic of Fiji , is an island nation in Melanesia in the South Pacific Ocean about northeast of New Zealand's North Island...
, Iwo Jima
Iwo Jima
Iwo Jima, officially , is an island of the Japanese Volcano Islands chain, which lie south of the Ogasawara Islands and together with them form the Ogasawara Archipelago. The island is located south of mainland Tokyo and administered as part of Ogasawara, one of eight villages of Tokyo...
, and even the Sea of Japan
Sea of Japan
The Sea of Japan is a marginal sea of the western Pacific Ocean, between the Asian mainland, the Japanese archipelago and Sakhalin. It is bordered by Japan, North Korea, Russia and South Korea. Like the Mediterranean Sea, it has almost no tides due to its nearly complete enclosure from the Pacific...
.