The last known passenger pigeon, named Martha, died 100 years ago today at the Cincinnati Zoo. She was 29.
The passenger pigeon, which once numbered in the billions in Norther America, has become a symbol of extinction. It was wiped out in the 19th century due to overhunting.
Animals face many natural threats, including changing temperatures, predators, and unexpected disasters. But no external stresses have proved more destructive to the survival of other living things than people.
The following gallery includes other animals that have gone extinct almost directly by the hands of humans.
The Tasmanian tiger, also called the thylacine, was a marsupial native to Australia and the island of Tasmania.
The carnivore was seen by farmers as a threat to sheep and therefore hunted, trapped and poisoned for government bounties.
'Many people, however, believe that bounty hunting alone could not have driven the thylacine extinct and therefore claim that an unknown disease epidemic must have been responsible,' researcher Thomas Prowse, of Australia's University of Adelaide, said in a statement.
Using population models to simulate the direct effects of bounty hunting and habitat loss, the new study found that humans alone were responsible for the animal's doom.
The last wild Tasmanian tiger was captured in 1933 and taken to the Hobart Zoo, where it died three years later.
The woolly mammoth disappeared about 10,000 years ago, after roaming Siberia and North America for around 250,000 years.
Although there's been some disagreement about what delivered the final blow, a recent study found that hunting by humans, on top of environmental stresses like climate and habitat change, spelled the end for the furry beast.
For centuries, the flightless Dodo bird lived undisturbed on the island of Mauritius off the coast of Africa. Because they had no enemies on the island, the wingless birds were easy prey when humans arrived in the early 16th century.
Although the exact date is uncertain, people believe the last dodo bird was killed in 1681.
Steller's Sea Cow was discovered in the Bering Sea by a Russian expedition in 1741. The giant seal-like creature, exploited for its meat and fat, was hunted at over seven times the sustainable limit. Hunting practices were also wasteful. 'Often, hunters would simply wade out to an individual, spear it, and then allow the animal to swim off, hoping that it would later die and drift to shore,' according to the California Academy of Sciences.
Only a small population of sea cows lived in the cold waters around Bering Island, and the mammal was eliminated by 1768.
The manatee, a living relative of the sea cow, faces a similar fate but for a different reason. While manatees are hunted for their meat and oil, collisions with motor boats remain the animal's biggest threat.
By the 1890s, the Passenger Pigeon had almost completely disappeared. The last captive Passenger Pigeon, named 'Martha,' died at the Cincinnati Zoological Garden in 1924, 100 years ago today.
The Passenger Pigeon was once the most ubiquitous bird in North America, numbering in the billions.
The bird was wiped out due to deforestation and over-hunting for their meat, following the arrival of European settlers in the 19th century.
This extinct antelope once lived throughout much of Northern Africa and the Middle East. It was pushed toward extinction by European hunters in the 1900s.
The last remaining Bubal Hartebeest was shot between 1945 and 1954 in North Africa.
The Javan tiger roamed the Indonesian island of Java in large numbers during the 19th century.
Humans played a large role in the tiger's demise, as they took over the animal's natural habitat and cleared trees. The tiger was also hunted and poisoned by natives, who considered the creature a pest.
The last documented observation of a Javan tiger was made in 1972.
The Zanzibar leopard, a subspecies of leopard that lived only on the Zanzibar archipelago of Tanzania, is believed to have gone extinct sometime in the mid-1990s.
The animal became the target of a brutal extermination campaign after many island natives believed the leopards were kept by witches to menace their fellow villagers.
Native to the Pyrenees in France and Spain, the Pyrenean Ibex became extinct in 2000 after the last known surviving individual was killed by a tree.
The form of wild goat was decimated by extensive hunting during the 18th and 19th centuries.
The International Union for Conservation of Nature declared Africa's Western Black Rhino officially extinct in November 2011. Rhinos are killed for their horns, believed in traditional Chinese medicine to cure fevers.
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