Plants and animals become extinct when they fail to adapt to changes in their environment, whether natural or man-made. Many scientists believe we are facing a 6th mass extinction, this time driven by the impact of humans.
The examples below highlight various ways we have wiped out wildlife in the past few centuries, including over-hunting, habitat destruction and the introduction of invasive species. Today, climate change, pollution and our ever-expanding population add to the threats.
Hundreds of thousands of great auks used to swim in and around the North Atlantic, ranging from Canada to Norway and including the UK. But centuries of intense exploitation drove them to extinction.
Huge numbers were slaughtered for their feathers, meat and oil. As they became rare, they were collected as prized objects. They were easy prey when they gathered on islands to breed and lay their single egg.
When did they go extinct? The last accepted sighting was in 1852, off Newfoundland.
Although the precise reasons for the extinction of this Australian marsupial are not known, humans contributed to their decline. In Tasmania, farmers persecuted the large carnivore for allegedly killing sheep, and bounties encouraged intensive hunting. They also faced increasing pressure from humans encroaching on their habitat.
When did they go extinct? The last known thylacine (shown in the photograph) died in 1936 at Hobart Zoo, Tasmania.
Known only from a small area in the Monteverde Cloud Forest Reserve, Costa Rica, this toad was once common there. Males were bright orange, while females were dark with yellow-edged red spots. Their breeding season was very short and involved pools that formed at the start of the rainy season.
Global warming, airborne pollution and the fatal fungal disease chytridiomycosis are all thought to have contributed to the population plummeting in the late 1980s.
When did they go extinct? The last documented sighting was of a single male toad in 1989.
Image credit: US Fish and Wildlife Service
Found only in the Yangtze River in China, this mammal was extremely well adapted to its environment. It used its long beak to probe the riverbed for food and echolocation to detect prey in the murky waters.
The dolphin became a casualty of illegal fishing practices, getting caught on fishing hooks and lines set for other species. It also suffered from the increasing degradation and pollution of its habitat, which is one of the world’s busiest and most populated waterways.
When did they go extinct? Declared functionally extinct in 2007. The last captive animal died in 2002.
Image © Institute of Hydrobiology, Chinese Academy of Sciences
These enormous birds could weigh over 250kg, as much as 3 men. So it’s no surprise that the Maori settlers who first encountered them on New Zealand saw them as a meal for the whole family. Unfortunately they didn’t know when to stop hunting them. Slow to reach sexual maturity, moa couldn’t reproduce fast enough to survive.
When did they go extinct? By about 1400, within 100 years of humans arriving.
Image © John Megahan, PLOS Biology, CC BY 2.5 license.
Once so numerous in North America that their flocks numbered in the billions, passenger pigeons also bred in vast colonies. The development of telegraph systems and railroads made it easy for hunters to target the birds wherever they massed. By 1878, around 50,000 were being killed every day for cheap meat, sport and feathers for mattresses.
When did they go extinct? The last known wild bird was shot in 1900. The last individual, Martha, died in Cincinnati Zoo in 1914.© Julian Hume
This tree, up to 4m tall, once grew on the isolated island of St Helena in the southern Atlantic Ocean. Humans destroyed its habitat through deforestation for timber and to make way for plantations. By the 19th century it had become very rare. Cultivation attempts met with very limited success.
When did they go extinct? Extinct in the wild since 1994, the last cultivated plant died in 2003.
Image © Rebecca Cairns-Wicks
The story of these land snails is a powerful example of the devastating impact non-native species can have.
The giant African snail, Achatina fulica, was introduced to the Society Islands in the South Pacific Ocean to be farmed for food. But it spread out of control, devastating plant life. So in the 1970s and 1980s the carnivorous rosy wolfsnail, Euglandina rosea, was introduced.
It was an ill-conceived attempt at biological control. Rather than eating its intended target, the wolfsnail devoured the tiny Partula snails, rapidly driving many extinct.
When did they go extinct? By the end of the 20th century, over 40 Partula species had been wiped out. Around 10 more survive only in captivity.