Jul 7

The Galápagos archipelago is known for its extraordinarily rich abundance and diversity of native plants and animals found nowhere else in the world. However invasive species present on islands are threatening the Galápagos’ rare species, pushing many to the brink of extinction. To date, seven vertebrate species have become extinct, while 40% of the still existing 96 species are endangered – with invasive species as the primary threat.

The world’s only marine lizard, the endemic Galápagos marine iguana, is extremely vulnerable to invasive species which consume the young and even occasionally adults

Island Conservation began working to protect species in the Galápagos Archipelago in 2008. In 2011,  the Galápagos National Park, supported by Island Conservation, Charles Darwin Foundation, The Raptor Center, and Bell Laboratories, removed invasive rats from the islands of Rábida, North Plaza, three Beagle islets, and three of the Bainbridge Rocks to protect 12 unique Galápagos species considered by the International Union for Conservation of Nature to be threatened with extinction.  One success story from this project was the rediscovery of a land snail species on Rábida Island, which was presumed to be extinct as no live specimens had been observed or recorded since 1905-1906.

In 2012, work began to remove invasive species from another island in the Galápagos Archipelago, Pinzón Island. Over 150 years ago, invasive black rats invaded this island and began feeding on the defenceless eggs and hatchlings of the Pinzón giant tortoise. By the turn of the 20th century the island endemic tortoise was unable to establish its next generation of tortoises, resulting in a captive rearing program being set up.

Pinzon giant tortoise 2

Adult Pinzón giant tortoise © Island Conservation

By December 2012, the project to remove the invasive rat species from this island was completed. With the removal of the last remaining invasive vertebrate species threat, tortoise hatchlings are now emerging from native tortoises on the island and the Galápagos National Park have successfully returned 118 hatchlings to their native island home.

The removal of invasive species from these islands is part of a much larger project to restore other key Galápagos Island ecosystems to protect native plants and animals. The next major endeavour is to remove multiple invasive species from Floreana Island. Feral goats have already been removed from the island, but other invasive species remain which are a threat to the island’s rich biodiversity. This rich biodiversity includes the Critically Endangered Floreana mockingbird which has disappeared from the island, mainly as a result of invasive species. Now only surviving on two small neighbouring islets, the removal of invasive rats and cats from Floreana will allow for this bird to comeback from the brink of extinction.

The Critically Endangered Floreana mockingbird

To find out more about the great work that Island Conservation carry out, visit their website or facebook page.

Jun 12

“When I first landed on what was Rat Island in 2007, it was an eerily silent place. A typical Aleutian island is teeming with wildlife, swirling with noisy, pungent birds. Not this place. It was crisscrossed with rat trails, littered with rat scat, scavenged bird bones, it even smelled…wrong,” reports Stacey Buckelew, an Island Conservation biologist. Buckelew first visited the island to help document centuries of damage to native birds and plant species from introduced invasive Norway rats.

Hawadax Island (formerly Rat Island), located in the Aleutian Islands off the coast of Alaska, is a 6,861 acre island uninhabited by humans. This treeless island has steep costal cliffs, a small central mountain range and broad rolling plateaus of maritime tundra. In the early 1780’s a shipwreck left the island with invasive Norway rats. Since their arrival the rats had decimated the islands native bird species by eating eggs, chicks, adult birds and plants.

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Hawadax Island (formerly Rat Island), Alaska © Island Conservation

In September 2008, Island Conservation, The US Fish and Wildlife Service and The Nature Conservancy successfully removed invasive rats from Hawadax Island. Following the removal of the rats all direct impacts, such as predation and competition for resources, immediately ceased.

Today the island is thriving. Since the removal of the rats, breeding tufted puffins (Fratercula cirrhata) have been documented on the island for the first time and species thought to have been extirpated due to the rats, such as Leach’s storm-petrels (Oceanodroma leucorhoa) and fork-tailed storm-petrels (Oceanodroma furcate), have been recorded.

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Tufted Puffins in waters around Hawadax Island, Alaska © Rory Stansbury / Island Conservation

Ground-nesting and shorebird numbers are increasing as well. A 2008 survey documented nine glaucous-winged gull nests whereas an identical survey carried out in the summer of 2013 discovered twenty eight nests, a three-fold increase. Black oystercatchers (Haematopus bachmani) and rock sandpiper (Calidris ptilocnemis) nests have also increased significantly. Song sparrows (Melospiza melodia), thought to be nearly extirpated by rats, and snow buntings, also decimated by rats, are rebounding as well.

Snow bunting in autumn

In 2012, Rat Island formally had its original Aleut name, Hawadax, restored in acknowledgement of the absence of rats.

To find out more about the great work that Island Conservation carry out, visit their website or facebook page.

Jemma Pealing, Arkive Content and Outreach Officer

Jun 10

Located 14 miles off the coast of California, Anacapa Island is the easternmost island in the Channel Islands Archipelago. Comprised of three islands strung closely together (East, Middle and West Anacapa), Anacapa Island is part of the Channel Islands National Park. Native species to the island include the Vulnerable Xantus’s murrelet (now renamed Scripps’s Murrelet), the endemic Anacapa deer mouse and the largest breeding colony of brown pelicans in California.

West and Middle Anacapa Islands, Channel Islands National Park, California, USA

Once an island with no natural predators for nesting birds, invasive non-native black rats were inadvertently introduced to the island from ships visiting the islands in the 1940’s. The invasive rats decimated native seabird populations by eating eggs and chicks. In 2001 and 2002, Island Conservation, the Channel Islands National Park, California Department of Fish and Game, the U.S. Fish and Wildlife and the National Oceanic and Atmospheric Administration removed the invasive rats from Anacapa Island. In the absence of these invasive predators Xantus’s murrelets (now renamed Scripps Murrelet) rebounded almost immediately with nesting success increasing by 91% the year after the rats were removed. The nesting success has remained at around 90%, compared to just 20% when rats were still there.

Xantus’s murrelet on water

This was not the only success story. Since the removal of the rats, ashy storm-petrels have been recorded nesting on the island for the first time ever and the Cassin’s auklet, a small seabird which had been unable to nest on Anacapa Island due to the risk of rat predation, has returned. Populations of the island’s only endemic mammal, the Anacapa deer mouse, are also thriving after the removal of the rats which used to compete with the mice as well as predating on them.

Ancapa deer mouse

Anacapa deer mouse © Jacob Sheppard/ Island Conservation

To find out more about the great work that Island Conservation carry out, visit their website or facebook page.

May 29

In a letter to Nature magazine, researchers have expressed their concern over the appearance of a non-native toad species, the Asian common toad, in Madagascar.

The Asian common toad (Duttaphrynus melanostictusi) is a close relative of the cane toad (Rhinella marina), an invasive toad species that rapidly spread across Australia after its introduction in the 1930s, and has devastated many native fauna and flora populations. First seen on Madagascar in March, the Asian common toad has been sighted several times in areas close to Toasmasina, the main port of the island nation. Worryingly, there have also been sightings of the amphibian just 25 kilometres from the Betampona Nature Reserve and short distances from other biodiversity hotspots. The dispersal of this species is not just limited to Madagascar and it is thought that populations may have also become established in other areas. One of the authors of the letter, Jonathan Kolby, of James Cook University in Queensland, Australia, said, ”There is now a high dispersal risk of these toads spreading from Madagascar to other Indian Ocean islands such as the Mascarene Islands, Comoros, and Seychelles.”

It is thought that populations may have also become established on other Indian Ocean islands, such as the Mascarene Islands

It is thought that the Asian common toad could have various negative impacts on the fauna of Madagascar, including spreading diseases such as ranavirus and chytridiomycosis to native amphibians and competing with them for food and breeding areas. This toad species is poisonous and is known to be toxic to animals that ingest it. Snakes are thought to be one of the animal groups most at risk from the invasion and there are over 50 endemic snake species on Madagascar, including the Madagascar ground boa. Other endemic species including fossas, lemurs, and birds will also be put at risk should the population of this harmful amphibian become established. Kolby also said, “It’s worrying because Madagascar has amazing endemic biodiversity – plants, animals, and amphibians that are found nowhere else. And this one species has the propensity to damage that.”

95 percent of the reptiles on Madagascar are endemic to the island, including the Madagascan ground boa

As well as being a threat to the animals of Madagascar, the Asian common toad is also a threat to the human population as it is known to contaminate drinking water and transmit parasites. After the devastation the cane toad has caused in Australia, it is thought that immediate action is required on Madagascar to prevent history from repeating itself. Kolby said, “The question is, can we still eradicate them? Have we caught it soon enough that eradication could be a feasible option? Obviously we all hope the answer is yes.” Suggested methods of eradication include removing adult toads, draining breeding ponds, and installing fences to prevent the toads from reaching water where they would be able to breed. Highlighting the urgency of the situation, Kolby said, ”Time is short, so we are issuing an urgent call to the conservation community and governments to prevent an ecological disaster.”

In Australia, the introduced cane toad is responsible for the declines of many native species, including the Near Threatened brush-tailed phascogale

Read more on this story at Nature – Toxic toads threaten ‘ecological disaster’ for Madagascar.

View images and videos of Madagascan species on ARKive.

Hannah Mulvany, ARKive Content and Outreach Officer

May 16

Island species are under threat.  Despite only making up about 3% of the Earth’s land area, islands are home to about 20% of all species and 50% of endangered species.

Approximately 80% of all known extinctions have occurred on islands. One of the primary causes for extinction of island species is the presence of invasive species. Since 1994, the charitable organisation Island Conservation has fought to prevent these extinctions by removing invasive species from island ecosystems.  Focusing on islands where the need is greatest, as biodiversity is concentrated and the rate of extinction is high, Island Conservation has deployed team members to 52 islands worldwide to protect 994 populations of 338 native species.

Invasive species are a threat to the Critically Endangered Juan Fernández firecrown

Once invasive species are removed, island ecosystems can often recover with little or no extra intervention. After the removal of invasive rats from Hawadax Island (formerly known as Rat Island), Alaska, bird species on the island increased dramatically and for the first time ever, breeding tufted puffins were documented on the island.

Working together with local communities, government management agencies and conservation organisations, Island Conservation enables many species to be brought back from the brink of extinction.

One such success story is the Anacapa Island Restoration Project. Invasive black rats on Anacapa Island, part of the Channel Islands Archipelago in California, were decimating native species populations, particularly the threatened Xantus’s murrelet (now renamed Scripps’s Murrelet),and the endemic Anacapa deer mouse. In 2001 and 2002, Island Conservation and partners removed invasive rats from Anacapa Island.  Since the removal of the rats, the nesting success of Xantus’s murrelet has increased by 90% and the Anacapa deer mice are thriving. In 2013, scientists documented the endangered ashy storm-petrel breeding on the island for the first time in history.

Anacapa Island

The removal of invasive species from island habitats has also led to the rediscovery of species once thought to be extinct. In 2011, Island Conservation and their partners removed invasive rats from Rábida Island, Galapagos to protect the native species.  A return visit to the island two years later led to an unexpected discovery of a gecko species, known only from subfossil records, which was thought to be extinct.

To date, Island Conservation have recovered and protected 338 seabird nesting colonies and taken action to restore 52 islands from the most damaging invasive animals.  With their continued work and the launch of Small Islands, Big Difference – a campaign which aims to save our world’s most vulnerable species by removing invasive species from islands at an accelerated rate, many more island species can be rescued from extinction.

Over the next few weeks we will be sharing with you more about the great work that Island Conservation have carried out.

For more information about Island Conservation visit their website or facebook page.

Discover ARKive’s favourite island species from around the world.

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