Major extinction events are nothing new for the planet, but species are now dying out at an alarming rate thanks to humans.
We are presently losing dozens of species every day, according to the Center for Biological Diversity. Nearly 20,000 species of plants and animals are at a high risk of extinction and if trends continue, Earth could see another mass extinction event within a few centuries.
"Unlike past mass extinctions, caused by events like asteroid strikes, volcanic eruptions and natural climate shifts, the current crisis is almost entirely caused by us -- humans," explains the Center for Biological Diversity. "In fact, 99 percent of currently threatened species are at risk from human activities, primarily those driving habitat loss, introduction of exotic species and global warming."
While there is no single international body that declares a species or subspecies extinct, the International Union for Conservation of Nature's Red List is a widely-recognized authority for keeping track of threatened and endangered species.
"The main focus of the Red List is to stop species from going extinct," a Red List manager told the Washington Post in 2011. "But, by default, we became the standard international list for extinctions."
Below, find 11 animals that have all gone extinct in the past two centuries thanks to humans.
The passenger pigeon may have once constituted 25 to 40 percent of the bird population in what is now the U.S., according to the Smithsonian Institution. As many as 3 to 5 billion of these birds were alive
when Europeans arrived.
The birds' traditional habitats were the large forests of eastern North America. As settlers cleared the forests for farmland, the pigeons turned to the new fields for subsistence.
"The large flocks of passenger pigeons often caused serious damage to the crops, and the farmers retaliated by shooting the birds and using them as a source of meat," explains the Smithsonian.
The 19th century brought widespread hunting and trapping of the birds, which severely diminished their populations. The last passenger pigeon, named "Martha,"
died at age 29 at the Cincinnati Zoo in 1914.
New York State Museum
Know as Tasmanian tigers due to their stripes, thylacines (Thylacinus cynocephalus
) were the largest modern carnivorous marsupial
according to the Smithsonian Institution.
They once existed across the Australian continent, but their habitat had been reduced to the island of Tasmania by the time European settlers arrived.
According the National Museum of Australia
Thylacines were believed to kill livestock and were often shot and trapped. They were a convenient scapegoat for poor financial returns and high stock losses at a time of rural depression in Tasmania.
Thylacines were declared a protected species in 1936, the same year the last known specimen died. Unconfirmed sightings of Tasmanian tigers continue to this day.
Using preserved specimens, a team at Pennsylvania State University has successfully sequenced the animal's mitochondrial DNA
The great auk (Pinguinus impennis
) was a flightless coastal bird that bred on rocky islands around the North Atlantic, including in Canada, Greenland, Iceland, the British Isles and Scandinavia.
They were slaughtered in huge numbers until the late 18th century
, according to the British Natural History Museum. Although hunting declined, the rare birds became a prized specimen for collectors and they were driven to extinction by the mid-1850s.
In this photo, Dan Gordon, Keeper of Biology at Tyne and Wear Archives and Museums, holds a stuffed juvenile Great Auk at the Discovery Museum in Newcastle.
The Bubal hartebeest, or Bubal antelope, (Alcelaphus buselaphus ssp. buselaphus
) was a subspecies of African antelope that lived in North Africa.
The animals were hunted to extinction and the last known Bubal hartebeest was killed in Algeria sometime between 1945 and 1954, according to the International Union for Conservation of Nature.