Island restoration
Encyclopedia
The ecological restoration of islands, or island restoration, is the application of the principles of ecological restoration to island
s and island groups. Islands, due to their isolation, are home to many of the world's endemic
species, as well as important breeding grounds for seabird
s and some marine mammal
s. Their ecosystems are also very vulnerable to human disturbance and particularly to introduced species
, due to their small size. Island groups such as New Zealand
and Hawaii
have undergone substantial extinction
s and losses of habitat
. Since the 1950s several organisations and government agencies around the world have worked to restore islands to their original states; New Zealand has used them to hold natural populations of species that would otherwise be unable to survive in the wild. The principal components of island restoration are the removal of introduced species and the reintroduction of native species.
, formulated by Robert MacArthur
and E.O. Wilson this is understood to be because isolation limits immigration of new species to the island, allowing new species to evolve. For example, 71% of New Zealand
's bird species (prior to human arrival) were endemic. Island species, as well as displaying greater levels of endemism, have characteristics that make them particularly vulnerable to human disturbance.
Many island species evolved on small islands, or even restricted habitats on small islands. Small populations are vulnerable to even modest hunting, and restricted habitats are vulnerable to loss or modification. More importantly, island species are often ecologically naive, that is they have not evolved, or have lost appropriate behavioural responses to predators. This often resulted in flightlessness, or unusual levels of tameness
. This made many species susceptible to hunting (it is thought, for example, that moa
s were hunted to extinction in a few short generations) and to predation by introduced species. Some, such as the Dodo
, are thought to have become extinct because of the pressure of both humans and introduced animals. One estimate of birds in the Pacific islands puts the extinctions at 2000 species. Between 40 to 50% of the bird species of New Zealand went extinct since 200 AD.
The field of island restoration is usually credited with having been started in New Zealand in the 1960s, but other smaller projects, such as the restoration of Nonsuch Island in Bermuda
(which began in 1962) have been going on for almost as long. Nevertheless, the program undertaken by the Department of Conservation
(DOC) is one of the largest in the world. It began on Cuvier Island
, where ecologists removed stock, goat
s, feral cats and finally, in 1993, Pacific Rats. The success of the project resulted in similar projects around New Zealand. The advantages to the DOC were considerable; in addition to protecting species endemic to smaller islands, like the Magenta Petrel
, islands near the mainland, once restored, could act as habitat for species of birds that were unable to survive on the mainland. Species like the Takahe
, where the remaining wild population was at considerable risk from feral cats and dogs, could be moved to these islands to safeguard the species.
. Since these species are most often the reason that native fauna and flora is threatened, their removal is essential to the restoration project. Islands are particularly suitable for restoration as once cleared of an introduced species they can be kept cleared of these species by virtue of being an island. Species removal is intensive and expensive, and methods used must be carefully chosen as to not create too much impact on non-target species. Feral cats, goats and three species of rats are among the most damaging species introduced to islands (Moors & Atkinson 1984). The differences in size, lifestyle and behaviour preclude the use of the same techniques for all of them, but with many species a range of techniques needs to be used in order to ensure success. Larger animals, such as goats and pigs, can effectively be hunted; in the case of Round Island
, in Mauritius
, all the goats were eliminated by a single marksman. On larger islands ecologists use a Judas goat
, where a radio collared goat is released into the wild. This goat is then followed and groups it joins are removed. To remove cats a combination of techniques is needed, both hunting, trapping and poisoning. Cats are more difficult to hunt than goats and pigs, requiring the use of experienced hunters and night hunting.
Trapping is ineffective for rats, given their sheer numbers, and the only method that works is poison
ing, which can be delivered into the field by broadcasting (by hand or from the air) or by the maintenance of bait stations. This method has been employed around the world, in the Falkland Islands
, in the tropical Pacific, and off New Zealand, where over 40 islands have been cleared. This method is not without problems, especially if the rats share the island with other, native species of rodent that might take the bait as well, as has happened on Anacapa Island
in the Channel Islands
. In the Pacific poison intended for rats was taken by land crab
s instead; the crabs were not affected by the poison but frustrated attempts to clear the rats.
The removal of invasive weed
s is, in most cases, more difficult than removing animal species. One such eradication was that of sandbur
, Cencrus echinatus, an introduced grass
on Laysan
. The grass, introduced to Laysan around 1961, had taken over 30% of the island by 1991, displaced the native bunchgrass, and reduced the breeding habitat of two endemic threatened species, the Laysan Duck
and Laysan Finch
, as well as those of several seabird
s. The removal took ten years, with controlled spraying for the first year, then individual removal of plants, then, when few plants were being found, sifting of the sands around plants to remove seeds. The cost of the eradication program was $150,000/year.
, where the potential benefits need to be weighed against the possibility of failure. Not all translocations succeed, and it may be necessary to help the reintroduced animals along with supplementary feeding or other kinds of management.
One other important aspect of restoration is prevention, that is, keeping invasive species from returning to a cleared island. This can be achieved by restricting access to the island in question (reducing possible instances of invasion) to more stringent quarantine methods. For example, in order to prevent invasive weeds from returning to Laysan people working on the island must bring entirely new clothes to the island, which must be frozen prior to arrival.
movement, which contends that the welfare
of the pests in question is not adequately addressed in island restoration plans. Because a broad spectrum of pest removal techniques needs to be used, including leg traps, animal rights campaigners accuse ecologists of cruelty, and indifference to non-targeted species that also take bait or are trapped, and suggest that more humane methods such as capture and sterilization be used instead (something those working in island restoration contend would be too expensive, and potentially ineffective see Kangaroo Island koala
s.). Some also defend the rights of the introduced species to exist as well. Others, including scientists affiliated with the animal rights movement, accept that when the choice is between the future of a species and a population of pests, the future of a species must take priority (with the caveat that the extermination is conducted as humanely as possible). Opposition to island restoration has not led to the abandonment of many projects but has delayed several, particularly through court action. Groups sometimes adopt different approaches; opponents of hedgehog
removal in the Outer Hebrides
offered bounties for live hedgehogs removed from the islands and relocated in their natural habitat. Invasive plants can also generate strong feelings. The removal of Eucalyptus
trees from Angel Island in San Francisco Bay
faced considerable opposition.
The Aleutian Islands, prior to the 18th century, lacked any terrestrial predators, but from the mid 18th century Arctic Fox
es were introduced to act as a source for the fur trade
, a practice that continued into the early 20th century. This introduction decimated the birds of the chain, particularly seabird
s like the Whiskered Auklet
. The reduction in seabirds, in turn, had effects on the ecology
of the islands, as many of the plants were dependent on the guano from nesting birds acting as a fertilizer. In the early 1950s managers of the Aleutian Islands Reservation became aware of the damage, and an eradication program began. Since then over 80 islands have been cleared of non-native foxes (only six islands remain) and bird populations have rebounded. Whiskered Auklets, which numbered 25,000 in 1974, had increased to 116,000 in 2003.
is a sub Antarctic
island 700 km south of New Zealand that became infested with rats in the 19th century. Several endemic birds, including the Campbell Teal and Campbell Snipe, only survived on small rocky islets just off the island, and the populations were perilously low. Several teals were taken into captivity for ex-situ conservation
, but once they had bred in captivity there was no-where else to return them to until the island was cleared of rats. The DOC's plan to remove rats from the island was one of the most ambitious attempted, as the island was so remote, the rat populations had the highest density of rats anywhere in the world, the weather treacherous and, at 113 km², it was the largest island at that point where eradication had been attempted. The poison had to be dropped in the winter, to minimize disturbance to nesting seabirds and reduce the chance of bird strike
for the pilots. After several experiments, the eradication began in 2001. In 2003 trackers with dogs were unable to find any rats. Soon after the island was cleared it was possible to return the teals to the island. Snipe have self-reintroduced to the island and have begun breeding.
Island
An island or isle is any piece of sub-continental land that is surrounded by water. Very small islands such as emergent land features on atolls can be called islets, cays or keys. An island in a river or lake may be called an eyot , or holm...
s and island groups. Islands, due to their isolation, are home to many of the world's endemic
Endemic (ecology)
Endemism is the ecological state of being unique to a defined geographic location, such as an island, nation or other defined zone, or habitat type; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. For example, all species of lemur are endemic to the...
species, as well as important breeding grounds for seabird
Seabird
Seabirds are birds that have adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same environmental problems and feeding niches have resulted in similar adaptations...
s and some marine mammal
Marine mammal
Marine mammals, which include seals, whales, dolphins, and walruses, form a diverse group of 128 species that rely on the ocean for their existence. They do not represent a distinct biological grouping, but rather are unified by their reliance on the marine environment for feeding. The level of...
s. Their ecosystems are also very vulnerable to human disturbance and particularly to introduced species
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...
, due to their small size. Island groups such as New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
and Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...
have undergone substantial extinction
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...
s and losses of habitat
Habitat (ecology)
A habitat is an ecological or environmental area that is inhabited by a particular species of animal, plant or other type of organism...
. Since the 1950s several organisations and government agencies around the world have worked to restore islands to their original states; New Zealand has used them to hold natural populations of species that would otherwise be unable to survive in the wild. The principal components of island restoration are the removal of introduced species and the reintroduction of native species.
Islands, endemism and extinction
Isolated islands have always been known to have greater levels of endemism; since the 1970s the theory of Island biogeographyIsland biogeography
Island biogeography is a field within biogeography that attempts to establish and explain the factors that affect the species richness of natural communities. The theory was developed to explain species richness of actual islands...
, formulated by Robert MacArthur
Robert MacArthur
Robert Helmer MacArthur was an American ecologist who made a major impact on many areas of community and population ecology....
and E.O. Wilson this is understood to be because isolation limits immigration of new species to the island, allowing new species to evolve. For example, 71% of New Zealand
Biodiversity of New Zealand
The biodiversity of New Zealand, a large Pacific archipelago, is one of the most unusual on Earth, due to its long isolation from other continental landmasses. Its affinities are derived from Gondwana, from which it separated 82 million years ago, New Caledonia and Lord Howe Island, both of which...
's bird species (prior to human arrival) were endemic. Island species, as well as displaying greater levels of endemism, have characteristics that make them particularly vulnerable to human disturbance.
Many island species evolved on small islands, or even restricted habitats on small islands. Small populations are vulnerable to even modest hunting, and restricted habitats are vulnerable to loss or modification. More importantly, island species are often ecologically naive, that is they have not evolved, or have lost appropriate behavioural responses to predators. This often resulted in flightlessness, or unusual levels of tameness
Island tameness
Island tameness is the tendency of many populations and species of animals living on isolated islands to lose their wariness of potential predators, particularly of large animals. The term is partly synonymous with ecological naïvete, which also has a wider meaning referring to the loss of...
. This made many species susceptible to hunting (it is thought, for example, that moa
Moa
The moa were eleven species of flightless birds endemic to New Zealand. The two largest species, Dinornis robustus and Dinornis novaezelandiae, reached about in height with neck outstretched, and weighed about ....
s were hunted to extinction in a few short generations) and to predation by introduced species. Some, such as the Dodo
Dodo
The dodo was a flightless bird endemic to the Indian Ocean island of Mauritius. Related to pigeons and doves, it stood about a meter tall, weighing about , living on fruit, and nesting on the ground....
, are thought to have become extinct because of the pressure of both humans and introduced animals. One estimate of birds in the Pacific islands puts the extinctions at 2000 species. Between 40 to 50% of the bird species of New Zealand went extinct since 200 AD.
Island restoration
Bermuda
Bermuda is a British overseas territory in the North Atlantic Ocean. Located off the east coast of the United States, its nearest landmass is Cape Hatteras, North Carolina, about to the west-northwest. It is about south of Halifax, Nova Scotia, Canada, and northeast of Miami, Florida...
(which began in 1962) have been going on for almost as long. Nevertheless, the program undertaken by the Department of Conservation
New Zealand Department of Conservation
The Department of Conservation , commonly known by its acronym, "DOC", is the state sector organisation which deals with the conservation of New Zealand’s natural and historic heritage...
(DOC) is one of the largest in the world. It began on Cuvier Island
Cuvier Island
Cuvier Island is a small island off the east coast of the North Island of New Zealand. It lies on the seaward end of the Colville Channel, north of the Mercury Islands and approximately south-east of Great Barrier Island...
, where ecologists removed stock, goat
Goat
The domestic goat is a subspecies of goat domesticated from the wild goat of southwest Asia and Eastern Europe. The goat is a member of the Bovidae family and is closely related to the sheep as both are in the goat-antelope subfamily Caprinae. There are over three hundred distinct breeds of...
s, feral cats and finally, in 1993, Pacific Rats. The success of the project resulted in similar projects around New Zealand. The advantages to the DOC were considerable; in addition to protecting species endemic to smaller islands, like the Magenta Petrel
Magenta Petrel
The Magenta Petrel or Chatham Island Taiko is a small seabird in the gadfly petrel genus, Pterodroma....
, islands near the mainland, once restored, could act as habitat for species of birds that were unable to survive on the mainland. Species like the Takahe
Takahe
The Takahē or South Island Takahē, Porphyrio hochstetteri is a flightless bird indigenous to New Zealand and belonging to the rail family. It was thought to be extinct after the last four known specimens were taken in 1898...
, where the remaining wild population was at considerable risk from feral cats and dogs, could be moved to these islands to safeguard the species.
Eradication of introduced species
One important aspect of island restoration is the removal of invasive speciesInvasive species
"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....
. Since these species are most often the reason that native fauna and flora is threatened, their removal is essential to the restoration project. Islands are particularly suitable for restoration as once cleared of an introduced species they can be kept cleared of these species by virtue of being an island. Species removal is intensive and expensive, and methods used must be carefully chosen as to not create too much impact on non-target species. Feral cats, goats and three species of rats are among the most damaging species introduced to islands (Moors & Atkinson 1984). The differences in size, lifestyle and behaviour preclude the use of the same techniques for all of them, but with many species a range of techniques needs to be used in order to ensure success. Larger animals, such as goats and pigs, can effectively be hunted; in the case of Round Island
Round Island (Mauritius)
Round Island is an uninhabited islet 22.5 kilometers north of Mauritius. It has an area of 1.69 square kilometers and a maximum elevation of 280 meters...
, in Mauritius
Mauritius
Mauritius , officially the Republic of Mauritius is an island nation off the southeast coast of the African continent in the southwest Indian Ocean, about east of Madagascar...
, all the goats were eliminated by a single marksman. On larger islands ecologists use a Judas goat
Judas goat
A Judas goat is a trained goat used at a slaughterhouse and in general animal herding. The Judas goat is trained to associate with sheep or cattle, leading them to a specific destination. In stockyards, a Judas goat will lead sheep to slaughter, while its own life is spared. Judas goats are also...
, where a radio collared goat is released into the wild. This goat is then followed and groups it joins are removed. To remove cats a combination of techniques is needed, both hunting, trapping and poisoning. Cats are more difficult to hunt than goats and pigs, requiring the use of experienced hunters and night hunting.
Trapping is ineffective for rats, given their sheer numbers, and the only method that works is poison
Poison
In the context of biology, poisons are substances that can cause disturbances to organisms, usually by chemical reaction or other activity on the molecular scale, when a sufficient quantity is absorbed by an organism....
ing, which can be delivered into the field by broadcasting (by hand or from the air) or by the maintenance of bait stations. This method has been employed around the world, in the Falkland Islands
Falkland Islands
The Falkland Islands are an archipelago in the South Atlantic Ocean, located about from the coast of mainland South America. The archipelago consists of East Falkland, West Falkland and 776 lesser islands. The capital, Stanley, is on East Falkland...
, in the tropical Pacific, and off New Zealand, where over 40 islands have been cleared. This method is not without problems, especially if the rats share the island with other, native species of rodent that might take the bait as well, as has happened on Anacapa Island
Anacapa Island
Anacapa Island is a small volcanic island located about off the coast of Port Hueneme, California, in Ventura County. The Island is composed of a series of narrow islets six miles long, running in a mostly east-west orientation, five miles east of Santa Cruz Island...
in the Channel Islands
Channel Islands of California
The Channel Islands of California are a chain of eight islands located in the Pacific Ocean off the coast of Southern California along the Santa Barbara Channel in the United States of America...
. In the Pacific poison intended for rats was taken by land crab
Crab
True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...
s instead; the crabs were not affected by the poison but frustrated attempts to clear the rats.
The removal of invasive weed
Weed
A weed in a general sense is a plant that is considered by the user of the term to be a nuisance, and normally applied to unwanted plants in human-controlled settings, especially farm fields and gardens, but also lawns, parks, woods, and other areas. More specifically, the term is often used to...
s is, in most cases, more difficult than removing animal species. One such eradication was that of sandbur
Sandbur
Cenchrus is a genus of about 25 species of grasses in the family Poaceae. Common names include buffelgrasses, sandburs, and sand spur. Some botanists include the genus within the related genus Pennisetum.-Species:...
, Cencrus echinatus, an introduced grass
Grass
Grasses, or more technically graminoids, are monocotyledonous, usually herbaceous plants with narrow leaves growing from the base. They include the "true grasses", of the Poaceae family, as well as the sedges and the rushes . The true grasses include cereals, bamboo and the grasses of lawns ...
on Laysan
Laysan
Laysan , located northwest of Honolulu at N25° 42' 14" W171° 44' 04", is one of the Northwestern Hawaiian Islands. It comprises one land mass of , about 1 by 1.5 miles in size . It is an atoll of sorts, although the land completely surrounds a shallow central lake some above sea level that has...
. The grass, introduced to Laysan around 1961, had taken over 30% of the island by 1991, displaced the native bunchgrass, and reduced the breeding habitat of two endemic threatened species, the Laysan Duck
Laysan Duck
The Laysan Duck , also known as the Laysan Teal because of its small size, is an endangered dabbling duck endemic to the Hawaiian Islands...
and Laysan Finch
Laysan Finch
The Laysan Finch is a species of finch in the Hawaiian honeycreeper subfamily, Drepanidinae, that is endemic to the Northwestern Hawaiian Islands. It is one of four remaining finch-billed Hawaiian honeycreepers, and is closely related to the smaller Nihoa Finch. The Laysan Finch is named for...
, as well as those of several seabird
Seabird
Seabirds are birds that have adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same environmental problems and feeding niches have resulted in similar adaptations...
s. The removal took ten years, with controlled spraying for the first year, then individual removal of plants, then, when few plants were being found, sifting of the sands around plants to remove seeds. The cost of the eradication program was $150,000/year.
Restoration of former habitat
In many cases the removal of introduced species is sufficient to allow a return to a pre-disturbance state, but generally active management, often in the form of replanting native flora and reintroduction of extirpated fauna is needed to achieve restoration goals. Planting of native species helps to replenish species that were either grazed or out competed. Species of animal can be translocated either from existing populations, or from captive bred populations. These reintroductions need to be carefully managed, particularly in the case of endangered speciesEndangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
, where the potential benefits need to be weighed against the possibility of failure. Not all translocations succeed, and it may be necessary to help the reintroduced animals along with supplementary feeding or other kinds of management.
One other important aspect of restoration is prevention, that is, keeping invasive species from returning to a cleared island. This can be achieved by restricting access to the island in question (reducing possible instances of invasion) to more stringent quarantine methods. For example, in order to prevent invasive weeds from returning to Laysan people working on the island must bring entirely new clothes to the island, which must be frozen prior to arrival.
Opposition to island restoration
Prior to the initial efforts to remove rats from New Zealand's offshore islands there was a great deal of skepticism as to the feasibility of island restoration amongst ecologists and conservation workers. However as the techniques have improved and larger islands have been restored, most of the initial criticisms from within the field have been dropped, in particular as the costs of eradication are often much lower than continuous pest control. Outside of the field of conservation there has been some opposition from other interested groups, particularly from the animal rightsAnimal rights
Animal rights, also known as animal liberation, is the idea that the most basic interests of non-human animals should be afforded the same consideration as the similar interests of human beings...
movement, which contends that the welfare
Animal welfare
Animal welfare is the physical and psychological well-being of animals.The term animal welfare can also mean human concern for animal welfare or a position in a debate on animal ethics and animal rights...
of the pests in question is not adequately addressed in island restoration plans. Because a broad spectrum of pest removal techniques needs to be used, including leg traps, animal rights campaigners accuse ecologists of cruelty, and indifference to non-targeted species that also take bait or are trapped, and suggest that more humane methods such as capture and sterilization be used instead (something those working in island restoration contend would be too expensive, and potentially ineffective see Kangaroo Island koala
Koala
The koala is an arboreal herbivorous marsupial native to Australia, and the only extant representative of the family Phascolarctidae....
s.). Some also defend the rights of the introduced species to exist as well. Others, including scientists affiliated with the animal rights movement, accept that when the choice is between the future of a species and a population of pests, the future of a species must take priority (with the caveat that the extermination is conducted as humanely as possible). Opposition to island restoration has not led to the abandonment of many projects but has delayed several, particularly through court action. Groups sometimes adopt different approaches; opponents of hedgehog
Hedgehog
A hedgehog is any of the spiny mammals of the subfamily Erinaceinae and the order Erinaceomorpha. There are 17 species of hedgehog in five genera, found through parts of Europe, Asia, Africa, and New Zealand . There are no hedgehogs native to Australia, and no living species native to the Americas...
removal in the Outer Hebrides
Outer Hebrides
The Outer Hebrides also known as the Western Isles and the Long Island, is an island chain off the west coast of Scotland. The islands are geographically contiguous with Comhairle nan Eilean Siar, one of the 32 unitary council areas of Scotland...
offered bounties for live hedgehogs removed from the islands and relocated in their natural habitat. Invasive plants can also generate strong feelings. The removal of Eucalyptus
Eucalyptus
Eucalyptus is a diverse genus of flowering trees in the myrtle family, Myrtaceae. Members of the genus dominate the tree flora of Australia...
trees from Angel Island in San Francisco Bay
San Francisco Bay
San Francisco Bay is a shallow, productive estuary through which water draining from approximately forty percent of California, flowing in the Sacramento and San Joaquin rivers from the Sierra Nevada mountains, enters the Pacific Ocean...
faced considerable opposition.
Island restoration projects
Island restoration has been attempted in many countries since the 1960s, and has met with varying degrees of success. The following examples highlight some of the factors that influence projects.Aleutian Islands
Arctic fox
The arctic fox , also known as the white fox, polar fox or snow fox, is a small fox native to Arctic regions of the Northern Hemisphere and is common throughout the Arctic tundra biome. The Greek word alopex, means a fox and Vulpes is the Latin version...
es were introduced to act as a source for the fur trade
Fur trade
The fur trade is a worldwide industry dealing in the acquisition and sale of animal fur. Since the establishment of world market for in the early modern period furs of boreal, polar and cold temperate mammalian animals have been the most valued...
, a practice that continued into the early 20th century. This introduction decimated the birds of the chain, particularly seabird
Seabird
Seabirds are birds that have adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same environmental problems and feeding niches have resulted in similar adaptations...
s like the Whiskered Auklet
Whiskered Auklet
The Whiskered Auklet, Aethia pygmaea, is a small seabird of the auk family. It has a more restricted range than other members of its genus, Aethia, living only around the Aleutian Islands and on some islands off Siberia , and breeding on these islands. It is one of the smallest alcids, only the...
. The reduction in seabirds, in turn, had effects on the ecology
Ecology
Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...
of the islands, as many of the plants were dependent on the guano from nesting birds acting as a fertilizer. In the early 1950s managers of the Aleutian Islands Reservation became aware of the damage, and an eradication program began. Since then over 80 islands have been cleared of non-native foxes (only six islands remain) and bird populations have rebounded. Whiskered Auklets, which numbered 25,000 in 1974, had increased to 116,000 in 2003.
Campbell Island
Campbell IslandCampbell Island, New Zealand
Campbell Island is a remote, subantarctic island of New Zealand and the main island of the Campbell Island group. It covers of the group's , and is surrounded by numerous stacks, rocks and islets like Dent Island, Folly Island , Isle de Jeanette Marie, and Jacquemart Island, the latter being the...
is a sub Antarctic
Antarctic
The Antarctic is the region around the Earth's South Pole, opposite the Arctic region around the North Pole. The Antarctic comprises the continent of Antarctica and the ice shelves, waters and island territories in the Southern Ocean situated south of the Antarctic Convergence...
island 700 km south of New Zealand that became infested with rats in the 19th century. Several endemic birds, including the Campbell Teal and Campbell Snipe, only survived on small rocky islets just off the island, and the populations were perilously low. Several teals were taken into captivity for ex-situ conservation
Ex-situ conservation
Ex-situ conservation means literally, "off-site conservation". It is the process of protecting an endangered species of plant or animal outside of its natural habitat; for example, by removing part of the population from a threatened habitat and placing it in a new location, which may be a wild...
, but once they had bred in captivity there was no-where else to return them to until the island was cleared of rats. The DOC's plan to remove rats from the island was one of the most ambitious attempted, as the island was so remote, the rat populations had the highest density of rats anywhere in the world, the weather treacherous and, at 113 km², it was the largest island at that point where eradication had been attempted. The poison had to be dropped in the winter, to minimize disturbance to nesting seabirds and reduce the chance of bird strike
Bird strike
A bird strike—sometimes called birdstrike, avian ingestion , bird hit, or BASH —is a collision between an airborne animal and a man-made vehicle, especially aircraft...
for the pilots. After several experiments, the eradication began in 2001. In 2003 trackers with dogs were unable to find any rats. Soon after the island was cleared it was possible to return the teals to the island. Snipe have self-reintroduced to the island and have begun breeding.
External links
- Island Conservation
- New Zealand Department of Conservation Ecological Restoration
- IUCN Proceedings of the International Conference on Eradication of Island Invasives
- UC Santa Cruz: Impact of Foxes in Alaska
- BBC News: New Zealand's pest eradication on islands
- UK SNH Uist Wader Project: impact of hedgehogs on wading bird breeding success
- SEAPRE: A Research Coordination Network whose purpose is to bring scientists from around the world together to understand the importance of seabirds and introduced predators for island function and conservation