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.

Nov 11

A project has begun on the Isles of Scilly to eradicate the invasive brown rat population in an attempt to secure the future survival of 14 seabird species.

The Isles of Scilly are composed of 5 inhabited islands and over 300 smaller uninhabited islands, which provide extremely important breeding habitats for many seabirds. There are 14 different seabird species which use the islands to breed, including the common tern, razorbill, lesser black-backed gull, puffin, shag and the European storm-petrel. In total, the breeding seabird population on all of the islands is around 20,000 individuals.

European storm-petrel image

The European storm-petrel is one of the 14 bird species which breed on the Isles of Scilly

An unwelcome visitor

The brown rat was first introduced to the Isles of Scilly from shipwrecks in the 18th century, which subsequently led to the establishment of a wild population. The brown rat is known to be one of the most successful and harmful invasive species in the world and causes tremendous damage to habitats it has been introduced to. On the Isles of Scilly, brown rats are known to predate the eggs and young of nesting birds, and they also carry and transmit various diseases. The total population of brown rats on the Isles of Scilly is thought to be around 34,500.

Brown rat image

Brown rat feeding on hen’s egg

How, where and when?

The project, starting at the beginning of November 2013, will cost over £755,000 and aims to eradicate the brown rat population on St. Agnes and Gugh, which are two of the inhabited islands in the Isles of Scilly. The company conducting the project is using techniques which have proven to be successful at eradicating brown rats in other areas while not causing damage to non-target species. Once all the brown rats are thought to have been eradicated from the two target islands, a long-term monitoring programme will begin and the local community will be encouraged to take precautionary measures to ensure that the areas remain rat free.

Puffin image

The Isles of Scilly provide an important breeding habitat for the puffin.

Taking responsibility

Johnny Birks, Chair of the Mammal Society, said, “Brown rats are not native to Britain… it’s our own fault they are so widespread and that makes it right for us to repair the damage we’ve caused.” The Heritage Lottery Fund and the EU Life Fund have both awarded money to the project, as have the Isles of Scilly Area of Outstanding Beauty Sustainable Development Fund and Natural England.

Read more on this story at BBC News – Isles of Scilly rat eradication to ‘save seabirds’ begins.

View photos and videos of bird species found in the UK on ARKive.

Hannah Mulvany, ARKive Content Officer.

Oct 1

Defending the United Kingdom against invasive, non-native species costs as much as £1.7 billion each year, according to a report by the BBC Countryfile programme.

Photo of a captive American mink on riverbank

The American mink has contributed to a rapid decline in the native water vole in the UK

Threat to native wildlife

The programme highlights the threats that so-called ‘alien’ species are posing to the UK’s native animals and plants, and the high cost of tackling the problem.

Invasive, non-native species are those which have been introduced by humans to areas outside of their natural range and, in the absence of natural predators and parasites, increase and spread to the detriment of native species and human interests. Worldwide, invasive species are considered to be the largest cause of biodiversity loss after humans.

Photo of common carp being fed on by an invasive species, the American signal crayfish

The signal crayfish is a voracious predator and has a negative impact on native crayfish species in Europe

Alien invaders

An example of a problematic invasive species in the UK is the zebra mussel, which arrived in the UK around ten years ago on the hulls of ships from Europe. This species reproduces so rapidly that it smothers native mussels and can block water systems. At Rutland Water in Leicestershire, England, the local water company has to spend around half a million pounds a year dealing with the species, and has installed filters to the reservoir to prevent the zebra mussels from spreading through and choking their water pipes.

Other well-known invasive species in the UK include the American mink, implicated in the decline of the water vole, and the grey squirrel, which is held largely responsible for the decline in native red squirrels.

Photo of grey squirrel collecting leaves in mouth

Introduced to the UK from North America, the grey squirrel has caused a decline in native red squirrels

Foreign plants are also causing major problems. Japanese knotweed alone is estimated to cost the UK economy £165 million each year to eradicate, and mortgages are being turned down due to the damage this species can do to properties. Of the £1.7 billion spent each year on dealing with invasive species in the UK, around £3 million goes towards clearing non-native weeds which can block canals, rivers and ponds.

Threats to health

As well as threatening native species and having an economic impact, invasive animals and plants can also pose risks to human health. For example, the sap of giant hogweed can cause painful blisters, while the hairy caterpillars of oak processionary moths can trigger allergic reactions.

Photo of bluebells in oak wood

Native UK bluebells are threatened by hybridisation with introduced Spanish bluebells

According to BBC Countryfile’s investigations reporter, Tom Heap, “From the grey squirrel, American crayfish, mink driving water voles from our river banks and the small but scarily named ‘killer shrimp’, a whole host of animals and plants are playing their part in colonising our countryside. Luckily, of the 2,000 non-native species living among us, only a few hundred are actually harmful.”


Read more about this story at The Telegraph – Defending UK from foreign species costs £26 per person.

Find out more about invasive species in the UK at the GB Non-Native Species Secretariat (NNSS).

View photos and videos of species from the United Kingdom on ARKive.

Liz Shaw, ARKive Text Author

Sep 5

Europe’s towns and cities are particularly vulnerable to the threats posed by invasive alien species, and experts say that action needs to be taken to control them.

Close up photo of a northern raccoon

Native to North America, the northern raccoon is an invasive species in parts of Europe

Invasive alien species are plants or animals that are not native to an area and which therefore lack natural predators, meaning they are able to spread rapidly.

Urban areas are at high risk from invasive species because of their large number of transport links, with many non-native animals and plants arriving accidentally at ports and airports. Some species also arrive through the plant and pet trades.

Threats to native wildlife

Invasive alien species can pose a significant threat to native wildlife, often through competition or predation.

Photo of red-eared slider ssp. elegans on rock

Abandoned pet turtles such as the red-eared slider can threaten native turtle species

According to Chantal van Ham, European Programme Officer for IUCN, “These non-indigenous species represent one of the main threats to the world’s biodiversity. This threat is set to increase unless meaningful action is taken to control their introduction and establishment.”

Non-native species can also cause problems for humans living in urban areas. For example, common ragweed, which is native to North America, is spreading rapidly across Europe and can cause hay fever and asthma-like symptoms. Other plants, such as Japanese knotweed, can cause structural damage to buildings.

IUCN conference

IUCN has recently released a publication entitled Invasive Alien Species: The Urban Dimension, which lists case studies from more than 15 European countries which show action being taken on invasive species in urban areas.

Photo of harlequin ladybird

The harlequin ladybird is an invasive insect that threatens native species in Europe and elsewhere

To address the issues posed by invasive alien species in Europe, IUCN is also hosting a conference today in Gland, Switzerland. The aim of the conference is to bring together local authorities, scientists, NGOs and policymakers to analyse the problem of invasive species in urban areas, and to discuss potential solutions.

Chantal van Ham said that local authorities have a key role to play in taking action to reduce the risk of invasive species becoming established. However, she added that it will be important for local authorities to have the support they need to do this.

European action

Photo of American bullfrog sitting on grass at the water's edge

The American bullfrog has been named one of the top 100 most invasive alien species in the world by IUCN

Next week, the European Commission is expected to publish its plans on tackling invasive species across Europe and to announce a legal framework which will require action to be taken on the issue in all EU member states. It will also look at the control methods which are available and the ways in which established invasive species populations can be managed.


Read more on this story at BBC News – Invasive alien species threaten urban environments and IUCN – Invasive alien species: the urban dimension.

You can also find out more about invasive species at the GB Non-native Species Secretariat and the IUCN/SSC Invasive Species Specialist Group.

Do you teach 11-14 year olds? Take a look at the invasive species teaching resource on ARKive’s education pages!

Liz Shaw, ARKive Text Author


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