Feb 7

Native ladybird species in the UK and Europe are declining rapidly due to the spread of the invasive harlequin ladybird, according to scientists.

Photo of harlequin ladybird

Harlequin ladybird

Invasive alien

Native to Asia, the harlequin ladybird (Harmonia axyridis) has been introduced to many countries as a pest control agent, but is now spreading rapidly and has itself become a pest species.

Introduced to North America in 1988, the harlequin is now the most widespread ladybird on the continent, and the species has also invaded much of northwest Europe. It was first spotted in Belgium in 2001, and arrived in the UK and Switzerland in 2004.

Since the harlequin’s arrival, scientists have warned about its potentially harmful impacts on native ladybird species. However, new research published in the journal Diversity and Distributions has now measured the scale of these impacts and demonstrated a strong link between the spread of the harlequin and rapid declines in native ladybirds.

Photo of harlequin ladybirds, showing variation in the species

Harlequin ladybirds showing some of the colour variation in this species

Rapid declines

Led by the Centre for Ecology and Hydrology in the UK, the study was made possible by thousands of records submitted as part of “citizen science” projects that record ladybird observations across Britain, Belgium and Switzerland.

Using this data, the researchers found that in the five years following the harlequin ladybird’s arrival in the UK, seven out of eight native ladybird species declined. Similar declines were also found in Belgium and Switzerland.

Particularly badly affected was the two-spot ladybird (Adalia bipunctata), which is estimated to have declined by 44% in the UK and 30% in Belgium. It is now difficult to spot in some areas where it was once common.

Outcompeted

Like many other native ladybirds, the two-spot ladybird is smaller than the harlequin and likely to be outcompeted for food and habitat. The harlequin is also likely to prey on the eggs and larvae of native ladybird species. In addition, the harlequin ladybird may potentially be more toxic than native species, giving it better protection against predators.

Photo of harlequin ladybird in flight

Harlequin ladybird in flight

Speaking about the results, Helen Roy of the Centre for Ecology and Hydrology said, “It’s a very real decline, which should be put amongst a whole other set of factors putting ladybirds in a more fragile situation.”

Such factors may include the intensification of agriculture and climate change.

The only UK species apparently unaffected by the harlequin’s arrival was the seven-spot ladybird (Coccinella septempunctata), which is similar in size to the harlequin and not in such direct competition for habitat as other native species.

Photo of seven-spot ladybird eating aphids

Seven-spot ladybird feeding on aphids

Ecosystem impacts

The researchers have warned of potentially serious consequences if the harlequin ladybird continues to spread. Ladybirds play an essential role in ecosystems, keeping pests such as aphids in check. Although the harlequin ladybird also feeds on aphids, having just one species playing this role could make the overall ecosystem weaker.

Tim Adriaens of the Research Institute for Nature and Forest (INBO) in Belgium, said, “At the continental scale, the arrival of the harlequin could impact on the resilience of ecosystems and severely diminish the vital services that ladybirds deliver.”

Read more on this story at BBC News – Ladybird decline driven by ‘invading’ harlequin and at The Telegraph – Harlequin ladybirds threaten British species.

Find out more about how to record UK ladybird sightings at The Harlequin Ladybird Survey and UK Ladybird Survey.

View photos and videos of ladybirds on ARKive.

Liz Shaw, ARKive Species Text Author

Jan 31

Non-native Burmese pythons are believed to be the cause of severe mammal declines in the Florida Everglades, according to new research.

Photo of Asiatic rock python (Python molurus bivittatus) resting in shallow water

Asiatic rock python (Burmese python) resting in water

Escaped pets

Also known as the Asiatic rock python, the Burmese python (Python molurus bivittatus) is a large constricting snake native to Asia. The exact origins of the pythons in the Everglades are unknown, but many have been imported into the United States through the pet trade, and some are likely to have escaped or been released into the wild.

In the absence of natural predators, the Burmese python population has exploded. Since 2000 the species has been recognised as being established across large parts of southern Florida, where it is known to eat a wide variety of mammals and birds.

Close up photo of Asiatic rock python showing heat receptors

Close up of Asiatic rock python showing heat receptors, used to detect the body heat of prey

Worrying mammal declines

In new research published in the journal PNAS, a team of scientists studied the number of live and dead mammals spotted along roads in the Everglades National Park. The team compared mammal surveys performed before and after the pythons became common, and found a strong link between the spread of the snakes and a decrease in many mammal species.

In particular, observations of racoons and opossums dropped by about 99%, while white-tailed deer fell by 94% and bobcats by 87.5%. No rabbits or foxes were seen during more recent surveys, despite rabbits being one of the most common mammals in earlier studies.

Most of these mammal species have been recorded in the diet of Burmese pythons in the Everglades National Park, with raccoons and opossums being particularly vulnerable to ambush as they often forage at the water’s edge.

Photo of Asiatic rock python with hog deer prey in water

Asiatic rock python killing hog deer

The decline in mammals was found to coincide with the spread of the pythons, with mammals being more common in areas were the pythons have only recently arrived, and most common outside of the python’s current range. The pythons are also likely to be eating other types of prey, including alligators.

We have documented pythons eating alligators, we have also documented alligators eating pythons. It depends on who is biggest during the encounter,” said Professor Michael Dorcas, one of the authors of the study.

Ecosystem impacts

The exact number of Burmese pythons in the Everglades is unknown, but their numbers are increasing year by year.

Any snake population – you are only seeing a small fraction of the numbers that are actually out there,” said Professor Dorcas. “They are a new top predator in Everglades National Park – one that shouldn’t be there.”

Photo of Asiatic rock python (Python molurus bivittatus) resting on foliage

Although a problem where it has been introduced in the US, the Asiatic rock python is classified as Near Threatened in its native Asia

Professor Dorcas has also stated that more research is needed to assess the potential impacts of the large mammal declines. “It’s not unreasonable to assume that any time we have major declines in mammals like this it’s going to have overall impacts on the ecosystem. Exactly what those are going to be, we don’t know. But it’s possible they could be fairly profound.”

Import ban

Earlier this month, it was announced that the US was poised to approve a ban on the import of Burmese pythons and on the sale of the snake across state lines. Another species that has been found in the Everglades, the African rock python, is also likely to be added to this list of “injurous” species.

Although reptile breeders and collectors have challenged the ban, and it would come too late to reverse the situation in Florida, Professor Dorcas has pointed out that it could help prevent the species from invading other suitable habitats in the United States, such as in southern Louisiana and south Texas.

Read more on this story at BBC – Pythons linked to Florida Everglades mammal decline.

View photos and videos of the Asiatic rock python on ARKive.

Liz Shaw, ARKive Species Text Author

Dec 28

This weeks A-Z blog has been inspired by a couple of recent school visits where the classes were looking specifically at endangered species and the responsibilities humans have to the environment. As the aim of ARKive is to raise awareness of threatened species worldwide it seems particularly fitting for the ‘E’ edition of A-Z to be endangered-themed, so please join me on my exploration of the endangered species of ARKive.

Photo of southern bluefin tuna swimming next to fish farm net

Southern bluefin tuna are endangered due to overfishing

Life on the EDGE

We work closely with lots of other global conservation organisations including our friends at the EDGE of Existence programme, who are working to promote and conserve the most Evolutionarily Distinct and Globally Endangered species. They are the only global conservation initiative to focus specifically on threatened species that represent a significant amount of unique evolutionary history, including weird and wonderful creatures such as the purple frog, the platypus and the shoebill.

Photo of Shoebill showing detail of head

The shoebill is a potential EDGE species

See where the golden-rumped sengi, pygmy three-toed sloth and Chinese giant salamander come on the blog of ARKive’s Top 10 EDGE species.

Extinction

The word that strikes fear into the hearts of all conservationists, which is hardly surprising considering that at present it is believed that 1/4 of all mammals and 1/3 of amphibians are at risk of extinction. It might sound rather odd but there are actually varying degrees of ‘extinct’ according to the IUCN Red List. Species can either be Extinct in the Wild (EW), which means the only remaining populations are captive, such as the scimitar-horned oryx, or Extinct (EX), such as the golden toad which was last seen alive in 1989.

Photo of a male golden toad

The golden toad is classed as Extinct (EX)

 

Ethiopian wolf

Living high in the Bale Mountains of Ethiopia this wolf is the most threatened canid in the world. Human encroachment on their habitat and its subsequent conversion to agricultural land is reducing their available habitat. With humans come their dogs, which carry diseases such as rabies and canine distemper to which the Ethiopian wolves have no resistance.

Photo of the Ethiopian wolf hunting

The Ethiopian wolf is the most endangered canid in the world

 

Ecuador

The South American country of Ecuador, nestled between Colombia, Peru and the Pacific Ocean, is host to a huge variety of species including the giant otter, the boto and the giant antpitta many of which are endangered. The Galapagos Islands are also part of Ecuador which means much of the Ecuadorian biodiversity is endemic. Species from the Galapagos, such as the Galapagos marine iguana, face a plethora of threats including the introduction of domestic pets, marine pollution and the effects of environmental fluctuations such as El Nino.

Photo of a male Galapagos marine iguana

The Galapagos marine iguana faces a number of threats

 

Watch out for our new Endangered Species education module and activity coming soon to our education pages. For more information why not check out our Endangered Species page.

What is your favourite ARKive E?  Perhaps you’re a fan of elephants or the echidna, how about the eastern sandfish or the earthworm? Let us know…

Laura Sutherland, ARKive Education Officer

Jul 26
Invasive species have long been identified by conservationists as one of the greatest threats to biodiversity. When introduced to natural ecosystems, invasive species can degrade habitats or harm native animals by preying on them or their prey.

However, a number of recent articles in influential scientific journals have questioned the urgency of addressing the threat to biodiversity from invasive species, amid concerns that conservationists may not be making the necessary distinction between invasive species and alien species in their desire to maintain pristine ecosystems.

Photo of a brown rat

The brown rat (Rattus norvegicus) has been the cause of many extinctions worldwide, particularly seabirds restricted to remote, predator-free islands.

Alien species are introduced outside their natural range by humans, and are in many cases harmless. Invasive species on the other hand, are not only introduced outside their range, but also cause substantial harm to biodiversity and human livelihoods. 

In certain cases, alien species may prove beneficial to human wellbeing. Examples include the honey bee, which has been introduced to North America, and various crops such as corn and potato which were introduced to Europe and have become staple dietary components for millions of people. 

Invasive species, not alien species, are however a major cause of biodiversity loss, and are implicated in the majority of extinctions recorded to date. 

To counter the concerns raised by some of the recent articles, a letter recently published in Science magazine aims to highlight the growing threat to biodiversity from invasive species, and addresses some of the dangerous misunderstandings of the issue.

Photo of a Cuban treefrog

The Cuban treefrog (Osteopilus septentrionalis) has been introduced to numerous Caribbean islands outside its native Cuba, and is preying on many rare amphibians.

The letter argues that the concerns raised over tackling the invasive species problem are unfounded, and that conservationists do recognise a clear distinction between alien species and invasive species. 

The letter is signed by several leaders of well-established and respected conservation organizations, including IUCN’s Director General, Julia Marton-Lefèvre; the Chair of the Species Survival Commission (SSC), Simon Stuart; and the Chair of SSC’s Invasive Species Specialist Group, Piero Genovesi. 

The authors highlight that threats from invasive species can be reduced, and that biodiversity can be protected through carefully targeted conservation interventions.

Photo of a swarm of honey bees

The honey bee has been beneficial to humans by providing food and pollinating crops.

Tackling invasive species also addresses the economic damage they cause and the serious threats that they pose to human health and livelihoods,” says Julia Marton-Lefèvre. 

Attempts to remove the most harmful invasive species are proving to be increasingly successful, with more than 1,000 eradications completed worldwide to date.” 

In speaking out and making clear the distinction between invasive and alien species, the authors of the letter have demonstrated their commitment to the fight against invasive species, and now call upon academics for support and, above all, action. 

Read the IUCN press release – Top scientists rally together in fight against invasive species.

Alex Royan, ARKive Species Text Author

Jul 19

Ten years ago the Cayman Island blue iguana numbered just two dozen individuals, but thanks to concerted conservation efforts this rare lizard is on the road to a remarkable recovery.

Photo of Cayman Island blue iguana resting on rock

Last ditch attempt to save the species 

Weighing in at over 11 kilograms and measuring over 1.5 metres in length, the Cayman Island blue iguana is by far the largest native animal on Grand Cayman, the only place in which it occurs. 

Predation was never a concern for this impressive lizard until cats and dogs were introduced to the island. Together with habitat destruction and collisions with cars, this has slowly pushed the species ever closer to extinction. 

In 2002, conservationists began a last ditch attempt to save the iguana. With help from local and international conservation partners, including the Wildlife Conservation Society and Durrell Wildlife Conservation Trust, the Blue Iguana Recovery Program has bred and released more than 500 blue iguanas back into the wild, increasing its population by twenty times.

Photo of Cayman Island blue iguana feeding

Remarkable success 

Blue iguanas are raised in captivity until two years old, when they are big enough to keep feral cats at bay. Once they hit two, the blue iguanas are released and monitored in the Salina Reserve on Grand Cayman. 

The programme has been such a success that conservationists have also started releasing blue iguanas into a new protected area, the Colliers Wilderness Reserve. This month, the programme confirmed the first breeding blue iguanas in the reserve. The goal is now to hit a population of 1,000 blue iguanas and, given recent success, this may be achieved fairly quickly.

Close up of a male Cayman Island blue iguana

For the past several years, we’ve succeeded in adding hundreds of animals to the wild population, all of which receive a health screening before release,” said Dr Paul Calle, Director of Zoological Health for WCS’s Bronx Zoo. 

Fred Burton, Director of the Blue Iguana Recovery Program, said: “We expect to reach our goal of 1,000 iguanas in managed protected areas in the wild in a few years. After that, we will monitor the iguanas to make sure they are reproducing in the numbers needed to maintain the wild population. If we get positive results, we will have succeeded.” 

View more images of the Cayman Island blue iguana on ARKive

Read the WCS press release – Grand Cayman blue iguana: Back from the brink of extinction.

Alex Royan, ARKive Species Text Author

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