Extinction, like death, is part of life and is an inescapable natural phenomenon that occurs with a certain cyclicality. Around 99 per cent of all species that have ever existed on Earth have died out, due to various factors such as environmental changes or the emergence of new species, giving rise to a constant turnover. Never before, however — at least based on what we know — have species been going extinct at such a rapid rate.

• Mammals
• Birds
• Reptiles
• Fish
• Invertebrates
• Plants

Life in the age of the sixth extinction

According to many experts, the planet is currently experiencing the sixth mass extinction in its history — one that has not yet reached the threshold of species loss that characterises such events, but that is proceeding at a faster rate than the previous five great extinctions. Under normal conditions, "the rate of speciation, that is, the emergence of new species, is higher than the extinction rate," science journalist Pietro Greco has written, and each year between one and ten species disappear.

Read also: Half of all species could become extinct by the end of the century

Over the past hundred years, however, this figure has grown exponentially and at least a thousand species a year are currently disappearing. The trigger for this great extinction is by now well known: it is humanity, which in a negligible space of time has devastated entire ecosystems, hunted numerous animals to extinction, introduced invasive species, and altered the composition of the atmosphere and the climatic and chemical equilibria of the oceans.

Extinction is forever

The list of species that have disappeared, directly or indirectly, because of Homo sapiens is vast and must be constantly updated. There is no coming back from extinction, and the disappearance of a species means the permanent loss of a particular piece of the living world — one that evolved and adapted to a specific environment — representing a loss for life on Earth as a whole.

Read also: Nature will need around 5 million years to recover from the extinctions we are causing

The list of species classified as extinct in the last decade

In the decade just ended, the International Union for Conservation of Nature (Iucn) classified 160 species as definitively extinct. These are mostly little-known and uncharismatic species, such as various invertebrates, and the majority of them had in fact been extinct for a long time. As a rule, it takes decades without any sightings before a species can officially be declared extinct. Below are the 160 living beings — animals and plants alike — that we will never see again.

Mammals

Bettongia anhydra

A small marsupial of the bettong genus, scientists observed only a single specimen, in 1933, and it has not been seen since. The decline of the species is believed to be linked to the arrival of rats and foxes in Australia. The Iucn declared it extinct in 2016.

Conilurus capricornensis

This small nocturnal Australian rodent, belonging to the genus Conilurus, was described on the basis of fossil remains. Scientists believe it became extinct due to the introduction of cats and changes in land use. The Iucn declared it extinct in 2016.

Dusicyon avus

This canid was once widespread across the grassy steppes of Patagonia and South America. Fossil remains found in graves suggest it may have been domesticated by humans. Analysis of the remains indicates the species became extinct between 326 and 496 years ago. Among the causes are hunting and competition with domestic dogs. In 2015 the species was added to the Iucn's list of extinct species.

Leporillus apicalis

These rats were known for building large nests in their habitat in southern Australia. The species was already rare at the beginning of the twentieth century, and is thought to have disappeared — possibly due to feral cats — around the 1930s and 1940s. The Iucn declared the species extinct in 2016.

Melomys rubicola

This small rodent, which lived only on a tiny coral island in the Torres Strait, between Australia and Papua New Guinea, can lay claim to the unenviable posthumous title of "first mammal species to become extinct directly as a result of the effects of anthropogenic climate change." The animal's restricted habitat — an island of just five hectares rising less than three metres above sea level — was affected by an increase in the frequency of storms that gradually destroyed the native vegetation on which the species depended. Scientists have not recorded a single specimen since 2009, and the Iucn declared it extinct in 2016.

Notomys robustus

The existence of this Australian rodent was discovered through the study of skulls found in owl pellets — regurgitated masses of indigestible food — from owls in southern Australia. The species is thought to have become extinct in the nineteenth century, and the Iucn added it to its list in 2016.

Pennatomys nivalis

A rodent of the family Cricetidae and the only species in the genus Pennatomys, it lived in the Lesser Antilles and formed part of the diet of indigenous populations. It probably disappeared following the arrival of European settlers and the non-native mammals that came with them, such as rats and mongooses. The Iucn officially declared it extinct in 2011.

Read also: First mammal declared extinct due to climate change

Pipistrellus murrayi

The Christmas Island pipistrelle, from the Australian territory of Christmas Island in the Indian Ocean, was declared extinct in 2017. In 2008 the population numbered just ten individuals, and the last specimen of this small bat — once common on the tiny island — was observed for the final time in 2009. The causes of its extinction are still unclear, given that the island's forests largely survived the arrival of humans. Scientists believe it was affected by the introduction of alien species, such as the yellow crazy ant (Anoplolepis gracilipes), the common wolf snake (Lycodon capucinus), cats and rats. The growing use of insecticides such as Fipronil may also have contributed to its decline.

Pseudomys auritus

Scientists know this species of large Australian rodent only through a handful of specimens collected by naturalists in the 1800s. These animals, which inhabited Australia's forests, are thought to have disappeared around 1850, and the Iucn declared the species extinct in 2016.

Sus bucculentus

The Indochinese warty pig was a species of wild pig that lived in Laos and Vietnam. It has not been observed since 1892, although some skulls found in 1995 raised hopes that the species might still be alive; however, according to genetic analyses, they were probably from another species of wild pig. The IUCN declared it extinct in 2016.

Read also: Humans make up only 0.01% of life on Earth, but have wiped out 83% of wild mammals

Birds

Acrocephalus luscinius

A small songbird that lived in the wetlands of the island of Guam, a United States territory located in Micronesia, in the western Pacific. Until 1968 it was a fairly common species, but since then its population suffered a sharp decline due to the introduction of non-native species such as cats, rats and brown tree snakes, the destruction of its habitat, and the increasing use of pesticides. It appears to have disappeared in 1969, and the IUCN declared it extinct in 2016.

Acrocephalus musae

A bird that inhabited bamboo forests on two islands of French Polynesia. This bird too is thought not to have survived the introduction of cats and rats to the islands, as well as an Asian bird species with which it competed, the common myna. The IUCN declared it extinct in 2016.

Acrocephalus nijoi

Like the two preceding species, another passerine of the family Acrocephalidae. Until 1995, these birds lived on the island of Aguijan, an uninhabited islet belonging to the Northern Mariana Islands in the Pacific Ocean. Like many island species, these birds are thought to have gone extinct due to the introduction of alien species by humans, such as cats, rats and lizards. The IUCN declared the species extinct in 2017.

Acrocephalus yamashinae

A passerine once widespread in the wetlands of the Northern Mariana Islands. The species is thought to have gone extinct before 1980 due to the destruction of its fragile habitat, which was definitively lost in 1981 as a result of a volcanic eruption. The IUCN declared it extinct in 2016.

Aegolius gradyi

The existence of this small owl, which inhabited the Bermuda Islands until the seventeenth century, was demonstrated only through the recent study of its fossil bones. The bird of prey is thought to have gone extinct following the arrival of settlers, who felled the trees in which it nested and introduced cats and rats. The IUCN declared it extinct in 2014.

Akialoa ellisiana

The greater akialoa belonged to the family Fringillidae and was characterised by a long, thin, curved bill. This small bird was endemic to the island of Oahu in the Hawaiian archipelago and was last sighted in 1894. The decline of this highly specialised species was caused by habitat degradation and the arrival of diseases transmitted by mosquitoes from introduced species. The IUCN declared it extinct in 2016.

Akialoa lanaiensis

Like the greater akialoa, the Lanai akialoa also probably went extinct at the end of the nineteenth century due to introduced diseases and the destruction of the forests that provided it with shelter and sustenance. The IUCN declared it extinct in 2016.

Akialoa stejnegeri

Unlike the two preceding species, the Kauai akialoa survived almost to the present day — the last sighting occurred in 1969. For this bird too, however, the combination of habitat destruction and the introduction of non-native species would prove fatal. The IUCN declared it extinct in 2016.

Alectroenas payandeei

The existence of this bird belonging to the family Columbidae was revealed to scientists through the study of fossil remains. The species is thought to have inhabited the island of Rodrigues in the Indian Ocean until the seventeenth century, when passing sailors accidentally introduced rats to the island, causing its rapid decline. The IUCN declared it extinct in 2014.

Aplonis ulietensis

The Raiatea starling lived in French Polynesia and is known only from a painting dating to the eighteenth century. It probably went extinct after humans brought rats to the island; its disappearance was officially recorded in 2016.

Read also: Alien species, a silent invasion threatening biodiversity

Bermuteo avivorus

The Bermuda hawk was the only representative of the genus Bermuteo. The existence of this bird of prey, endemic to the Atlantic Ocean island, was discovered through the study of fossil remains dating to the seventeenth century. It is believed to have disappeared due to hunting and the introduction of non-native species. The IUCN declared it extinct in 2014.

Chenonetta finschi

A large duck, almost incapable of flight, once lived in the forests of New Zealand. Scientists established this through fossils found on the island. The bird is thought to have gone extinct around 1500, due to hunting and the introduction of invasive species. The IUCN added it to the list of extinct species in 2017.

Coenocorypha barrierensis

This snipe, endemic to New Zealand, was last seen in 1870. The introduction of mammals to the island probably caused its extinction. The IUCN declared the species extinct in 2016.

Coenocorypha iredalei

This bird of the family Scolopacidae also lived in New Zealand and is thought not to have survived the introduction of invasive mammals, such as the black rat. The IUCN declared the species extinct in 2016.

Colaptes oceanicus

This species of Bermuda woodpecker, recently described thanks to the discovery of fossil remains, is thought to have gone extinct in the seventeenth century following the arrival of European settlers, who felled the trees in which it lived and introduced non-native species. The IUCN declared this bird extinct in 2017.

Columba thiriouxi

Until 1730, this small dove lived undisturbed on the island of Mauritius in the Indian Ocean. Its extinction was probably caused by hunting for its meat and the arrival of black rats. The IUCN declared it extinct in 2017.

Dryolimnas augusti

A flightless bird resembling a chicken in appearance, which lived on the island of Réunion in the Indian Ocean, declared extinct in 2014. The species is thought to have evolved in the absence, or near-absence, of predators and would have lacked the means to defend itself against cats and rats introduced by humans.

Eclectus infectus

Naturalists described this parrot species only recently, thanks to fossil bones found in the Tonga archipelago. Hunting and invasive species are thought to have caused its extinction. The IUCN declared it extinct in 2014.

Read also: Nature will need around 5 million years to recover from the extinctions we are causing

Foudia delloni

A species of songbird known for weaving particularly intricate nests, which lived on the island of Réunion. The human introduction of rats to the island probably led to its extinction towards the end of the 1600s. The IUCN added it to the list of extinct species in 2016.

Hemignathus lucidus

A Hawaiian bird characterised by its long, curved bill, last observed at the end of the nineteenth century. Its disappearance is probably linked to deforestation and the introduction of invasive species such as rats and mongooses, and the consequent proliferation of new diseases. The IUCN officially declared it extinct in 2016.

Himatione fraithii

This bird lived on the Hawaiian island of Laysan and was last observed by naturalists in 1923. It is thought to have disappeared due to competition with rabbits introduced by humans, which would have destroyed the plants it depended on for food. The IUCN added it to the list of extinct species in 2017.

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