Last March, the world's last male northern white rhino, Sudan, died at 45 years of age.
Sudan — who is named for his country of birth and lived under the protection of armed guards at the Ol Pejeta Conservancy in Kenya, away from poachers — suffered from a degenerative muscle and bone condition and was euthanized.
Fortunately, scientists were able to gather genetic material that could one day be used to create more northern white rhinos through IVF. Sudan also left behind a daughter and granddaughter, so there's a flicker of hope for the wildlife preservation community.
Even so, there are numerous other animal species and subspecies that are in danger of perishing for good. The Amur leopard and Sumatran elephant are just two of 19 species categorized as "critically endangered" by the World Wildlife Fund, while the white-rumped vulture, Philippine crocodile, and Chinese pangolin have been given the equivalent classification on the IUCN Red List.
The Amur leopard is one of the world's most endangered wildcats, and native to the Russian Far East.
This subspecies — which is also known as the Far East leopard, the Manchurian leopard, or the Korean leopard, despite being nearly extinct outside of the Amur River basin in eastern Russia — can run upwards of 37 miles an hour and jump as high as 19 feet in the air.
According to a 2015 census, there are only around 60 Amur leopards left, all living at Russia's Land of the Leopard National Park.
In the the past 60 years, there has been a 50% decline in the Bornean orangutan population.
Found only on the island of Borneo, Asia's largest island, Bornean orangutans have broader faces and shorter beards than their arboreal Sumatran cousins.
There are three subspecies of Borean orangutans: Northwest, Northeast, and Central. The largest is the Central subspecies, of which there are an estimated 35,000. The most threatened is the Northeast subspecies: due to its habitat being decimated by logging and hunting, there are only about 1,500 extant Northeast Borean apes.
Scientists predict that the Bornean orangutan population will fall another 22% by 2025, bringing the total number down to 47,000.