Jul 27

A herd of Critically Endangered Przewalski’s horses are under threat from illegal poaching, according to scientists.

Photo of Przewalski's horses grazing

The herd is located in the Chernobyl exclusion zone in the Ukraine, where 31 individuals were released into the wild in 1998 and 1999. The horses were taken from a Przewalski’s horse reserve and from a local zoo, and were released to help restore and enrich the biodiversity of the area.

The Przewalski’s horses initially seemed to be doing well, with 86 foals born in the zone between 1998 and 2007. According to a review published in the Bulletin of Moscow Society of Naturalists, the population peaked at 65 individuals in 2003 and 2004.

Photo of Przewalski's horse mare and foal interacting

Vulnerable herd under threat

Unfortunately, this vulnerable herd has since been almost halved by illegal poaching, with over 70% of deaths from 2004 to 2006 being caused by human hunters. As well as threatening the survival of the herd, this drop in numbers may also increase the risk of inbreeding.

Many people in this part of Ukraine are very poor,” said Professor Tim Mousseau, a biologist from the University of South Carolina who visits the Chernobyl exclusion zone at least twice a year. “So access to a readily available supply of horsemeat is tempting for people.”

Mousseau also questioned the wisdom of releasing the vulnerable horses into a contaminated area.

Photo of a group of Przewalski's horses running

Last true wild horse

The last true wild horse, Przewalski’s horse was driven to extinction in the wild in the 1960s as a result of hunting, habitat loss and competition with domestic livestock. Fortunately, captive breeding and reintroduction efforts now mean that a number of populations of Przewalski’s horse have been re-established in the wild in its native Mongolia.

However, like many of these reintroduced populations, the Przewalski’s horses at Chernobyl still face further threats from habitat loss and potential hybridisation with domestic horses. The herd at Chernobyl has not been counted for the past three years, and it is unclear how many of these Critically Endangered wild horses now remain.

Find out more about the conservation of Przewalski’s horse at the Foundation for the Preservation and Protection of the Przewalski Horse.

View photos and videos of Przewalski’s horse on ARKive.

Read the full BBC story – Chernobyl’s Przewalski’s horses are poached for meat.

Liz Shaw, ARKive Species Text Author

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 26

Cold, wet, dark… but lifeless? Certainly not! Caves are home to many weird and wonderful lifeforms with special adaptations that make living in this inhospitable environment possible. Here are our top ten troglobiotic species!

Winter wren

Winter wren photo

Strangely our first selection doesn’t live in caves at all. The scientific name of the winter wren Troglodytes troglodytes means cave dweller but this name actually comes from the way it hunts insect prey by nipping in and out of cracks and crevices.

No-eyed big-eyed wolf spider

No-eyed big-eyed wolf spider photo

When you spend all your time in the dark eyes become an unnecessary but expensive organ to maintain. Many cave species have lost their eyes altogether resulting in an identity crisis for the no-eyed big-eyed wolf spider.

Alabama cave crayfish

Alabama cave crayfish photo

A life without sunshine makes protective pigmentation unnecessary. For the Alabama cave crayfish this adaptation has made its shell translucent so it’s possible to have a peek at its insides.

Fungus gnat

Fungus gnat photo

Colonies of fungus gnat larvae hang silk threads covered in sticky beads of slime from cave roofs to catch their prey. These gruesome youngsters use bioluminescence to lure flying insects into their dangling traps.

Velvet worm

Velvet worm photo

Another pigment free cave dweller is this species of velvet worm, it is one of only two troglobiotic velvet worms to have ever been discovered.

Madagascan rousette

Madagascan rousette photo

When asked to think of animals that live in caves bats are likely to spring to mind, but many bats don’t roost in caves at all, preferring a nice snug hollow in a tree. The Madagascan rousette is one species of bat that will roost in caves.

Cave salamander

Cave salamander photo

This cave salamander is also known as the human fish. Apparently its fleshy skin makes it resemble a small person. Subterranean darkness must be the only place that this beast could be mistaken for a human!

Iran cave barb

Iran cave barb photo

Like most cave species the range of the Iran cave barb is highly restricted. This fish has only been found in one subterranean river system in south-west Iran.

Nelson cave spider

Nelson cave spider photo

The Nelson cave spider is an ambush predator that hunts in the complete darkness of its limestone cave habitat. It is New Zealand’s only protected spider and also its largest.

Cave catfish

Cave catfish photo

The cave catfish is found in the Aigamas Cave in Namibia. An opportunistic feeder it’s only apparent food source is the particles that fall into the lake from the cave above including bat droppings and animal carcasses.

Have you found an interesting cave species on ARKive that doesn’t feature in our top ten? If so, tell us about it!

Eleanor Sans, ARKive Media Researcher

Jul 22

It’s that time of year again when we’re all dreaming of our summer holidays. Luckily, ARKive species have shared their favourite holiday postcards with us. Whether you’re staying at home or jetting off to an exotic location, ARKive’s Top Ten beach shots will get you in the mood for sand, sun and swimming.

King penguin

King penguin photo

Who wouldn’t want to walk along a beach that’s this beautiful? King penguins are very sociable birds – they live in groups ranging from 30 individuals to hundreds of thousands, on beaches in South Georgia and the Falkland Islands.

Coconut crab

Photo of coconut crabs on the beach

Coconut crabs live on idyllic tropical islands in the Indian and Pacific oceans and can grow up to one metre long! Coconut crabs climb palm trees and pinch off coconuts with their powerful claws. If the coconut doesn’t break open when it hits the ground, the crabs use their sharp legs to get the flesh inside.

Striated caracara

Photo of a striated caracara running along a beach

Check out the athleticism of this striated caracara! Running along the beach with its wings spread, it looks like it’s practicing for the London 2012 Olympics.


Photo of a gewa in seashore habitat

Although the gewa – a type of mangrove – looks pretty along the seashore, it’s actually poisonous. Natives in New Guinea use the sap as an ingredient in arrow poison to hunt fish. In some countries it’s known as ‘Blind Your Eye’ – if the milky sap gets in the eyes it can cause temporary blindness.

Green turtle

Photo of green turtle hatchlings making their way to the sea

Green turtles return to the same beach to breed each season, a tremendous feat of navigation. Some populations migrate over 2,000 kilometres! Females dig a large nest, laying around 100-150 eggs before covering the nest in sand. When the hatchlings emerge, they make their way to the sea where they remain until they reach sexual maturity.

Banded sea krait

Photo of a banded sea krait on the beach

Banded sea kraits are amphibious snakes – they spend most of their life at sea, but come ashore to reproduce. The tail is paddle-shaped, which helps it to swim, and it has large lungs so it can spend long periods underwater. Although the banded sea krait is venomous, it’s not aggressive toward swimmers and divers.

South American sea lion

Photo of a male South American sea lion charging

I don’t think I’d want to see this South American sea lion charging towards me on the beach – males can grow to nearly 3 metres and weight around 350 kilograms!

Aldabra giant tortoise

Photo of an Aldabra giant tortoise walking along the beach

Check out the beachside view! Aldabra giant tortoises are endemic to the islands of Aldabra and the Seychelles, but have since been introduced to Mauritius and Reunion. As they are an endangered species, classified as Vulnerable on the IUCN Red List, these introductions are important to maintain the population of Aldabra giant tortoises.

Falkland steamerduck

Photo of Falkland steamerduck chicks huddled on the beach

Falkland steamerduck chicks huddle together on the shoreline, waiting for their parents to return with a tasty dish of regurgitated marine molluscs and crustaceans. Mmmm – mushed up crab, anyone?

Hawaiian monk seal

Photo of a Hawaiian monk seal hauled out on the beach

Hawaii is a beach lover’s paradise. Hawaiian monk seals can be found hauled out on Hawaii’s uninhabited tropical islands, making the most of the sun in between regular foraging trips.

Do you have a favourite beach shot on ARKive? Let us know!

Want to see what some of the ARKive species have been up to on their holidays? Find out in this months ARKive enews!

Ruth Hendry, ARKive Media Researcher

Jul 21

Welcome to ARKive’s Blog of Bleurgh. That’s right people – animals and plants aren’t all the white knights they’re often made out to be. “Chum” from Finding Nemo had it right – cute, clappy dolphins just aren’t cool. Compare them to his species – a mako shark. An awesome predator and one of the fastest fish in the ocean. No competition, really.

So, are you tired of cute and fluffy animals taking the limelight? Your search for the real, unadulterated, potentially horrifying side of the natural world is over – but your understanding of why nature can be so beautiful in the way it adapts and makes a living by being utterly horrifying, is only just beginning…


Cannibalism (the eating of one’s own species) is rife in the animal kingdom – sometimes the need for survival is so great that one has to turn on one’s own kind. Or sometimes its just part of a mating ritual, like one of the most well-known cannibals of all, the black widow spider. After mating with the male, the female black widow makes a habit of eating her partner. Nice.

Photo of a female black widow spider


There’s no easy way to introduce this – eating faeces. This is most commonly seen in herbivores, for two reasons:

  1. Eating one’s own poo gives inefficient digesters of plants a second chance at gaining important nutrients – for example rabbits, gorillas and capybaras.
  2. Eating one’s mother’s poo helps infants to cultivate gut bacteria important in the digestion of plant material – for example koalas, where the joey eats the mother’s “pap”.

Eastern gorilla photo


Feeding on dead animals or plants. There are more scavengers in the natural world than I have time to list here – but as this is a competitive habit, scavengers are ruthless in their pursuit of carrion. The pomarine jaeger and northern giant petrel are excellent examples of seabird scavengers.

Photo of northern giant petrels feeding on an elephant seal carcass

Worst smell

The natural world is an undoubtedly smelly place – as sense of smell is an important method of communication and having a certain pong tends to pay off. No more so than the titan arum, the plant with the largest flower in the world. In this case, being absolutely huge isn’t enough to attract the insects it needs for pollenisation, so the titan arum flower emits a stench not dissimilar to rotting flesh, earning it the title “corpse flower” amongst locals.

Titan arum photo

“If you have any poo, throw it now”

I apologise – back to poo again. Throwing the stuff is common behaviour amongst chimpanzees and other primates. It’s an aggressive display to guard their territory. Ok, I’ll stop talking about poo now. Here’s what it looks like, though.

Photo of chimpanzee faeces


Parasites tend to have evolved elaborate and often stomach-churning ways of taking advantage of their hosts. Ichneumon wasps are great examples. They lay their eggs in caterpillars, and the resulting wasp larva develops inside the unfortunate host, eating its internal tissues and eventually killing the caterpillar after it pupates. Not a pretty way to go!

Ichneumon wasp photo


This is definitely one of the more sinister behaviours. Some orcas have a somewhat less respectful way of treating the corpses of their prey, swimming underneath and using their powerful tails to propel them metres above the ocean.

Orca photo


You know how Gremlins, the fictional film monsters, gave birth to baby Gremlins when they were exposed to water, and how the baby Gremlins popped off their parent’s back with grotesque popping sounds? Here’s the real life version. The eggs of the Suriname toad are embedded in the female’s back during amplexus, where they are nurtured through the tadpole stage and emerge as fully-formed frogs. Gross. I don’t think they make the popping sound, though.

Photo of a Suriname toad with young emerging from its back


A type of parasitism, vampirism is thought to have evolved in some species as a response to extreme environments where other food sources are scarce. Introducing the “vampire finch” – some short-beaked ground-finches feed on the blood of the other inhabitats of their dry, food-scarce Galapagos Island habitats. On top of this, they have also learnt some ingenious ways of getting to the nutritious contents of Nazca booby eggs. An excellent example of “culture” in the animal kingdom.

Sharp-beaked ground-finches feeding on blood drawn from nazca booby feathers


Being a scientific organisation, ARKive tries not to use human terms to describe animal behaviour – but for want of a better word… the magellanic penguin below looks innocent enough doesn’t it? This is probably just what a film crew from NDR Naturfilm thought when they decided to film a documentary following one of these beautiful creatures. Little did they know that they would end up filming an incredible example of inexplicable and “cruel” animal behaviour. The male subject of this film was relentlessly chased down and pecked to death by a competitive male. You can view the video on ARKive here, but be warned, it’s not for the feint of heart.

Magellanic penguin photo

So, that concludes our countdown of ARKive’s Top 10 Natural Nasties. As horrifying as they are, the blessing is that we have only covered the species we have on ARKive. There’s many more out there that are just as gross and would be very happy to make you their host. So watch out!

Charlie Whittaker, ARKive Media Researcher


RSS feedArkive.org is the place for films, photos and facts about endangered species. Subscribe to our blog today to keep up to date!

Email updates

Sign up to receive a regular email digest of Arkive blog posts.
Preferred frequency:

Arkive twitter

Twitter: ARKive