The Holocene extinction event is a term used to refer to the ongoing extinction of numerous animal species due to human activities. It is named after the geologic period of the Holocene, which began 11,550 years ago (about 9600 BC) and continues to the present. The Holocene extinction has eliminated between 20,000 and several hundred thousand species over the course of the last 12,000 years. The Holocene extinction is composed of two major pulses: one pulse 13,000 to 9,000 years ago, during the end of the last glacial period, when much of the Pleistocene megafauna went extinct, and a recent pulse, starting around 1950, when mass deforestation and other human activities have resulted in the extinction of many species.
Animal species extinct from the first pulse of the Holocene extinction include several species of mammoth, the dire wolf, short-faced bear, cave lion, cave bear, cave hyena, dwarf elephants, giant swan, giant rat, mastodon, American cheetah, ground sloths, marsupials of many species, numerous giant flightless birds, and many other animals. Most scientists are in agreement that these animals went extinct due to human activity, as many of them disappear within 1,000 years of the introduction of humans to an area. Some of the most precise findings are from evidence in Australia and the Americas, which were relatively isolated until the arrival of humans.
Animals that have gone extinct recently, during the latest pulse of the Holocene extinction, include the dodo, aurochs (a large type of horned cattle), the tarpan (a small horse), the Tasmanian Tiger, the quagga (a zebra relative), Steller's Sea Cow (relative of the manatee and Dugong), the giant Aye-aye (a nocturnal primate), the Great Auk (a penguin-like bird from the Atlantic region), the passenger pigeon (with about five billion birds in North America, was formerly one of the most numerous birds on the planet), the Golden Toad of Costa Rica, and many others. Biologists agree that the current extinction rate of animal species is several hundred times higher than the typical background level.