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An animal species becomes extinct when no specimens remain alive, although breeding capabilities may have already ceased. Because many animals have a large natural habitat, exact dates of extinction are often difficult to determine. Historically, animal extinction has been caused by many factors including climate change, massive planet events such as meteor impact, prevailing genetic problems and destruction by predators. Most commonly in modern times, extinct animal species have been largely killed off by human influence, with some experts suggesting that human encroachment will cause half of all life forms to become extinct within the next century. In the animal world, the reality of modern animal extinction is already comprehended.
One of the most well-known of the extinct animal species was only discovered a few decades before its disappearance. In 1741, German naturalist Georg Stellar discovered an enormous cousin of the manatee living in the northern Pacific Ocean. The Stellar’s Sea Cow, as the gentle creature was called, reached up to 25.9 ft (7.9 m) in length and could weigh up to 6,000 lbs (2,721 kg.) Stellar carefully studied the animal and gave us all the information that exists about them today. Due to hunting, the largest of the sirenian order became extinct within 30 years.
One of the major causes of extinct animal species in Australia is the human importation of non-native predator species, such as foxes and house cats. Small mammals, particularly marsupials and birds, are unused to these aggressive predators and have little to no defensive ability against them. Nearly 30 Australian marsupial and rodent species have become extinct since the 18th century, including the pig-footed bandicoot, lesser bilby, eastern hare-wallaby, and big-eared hopping mouse. Imported species are believed to be a primary cause of most of these extinctions.
Modern extinctions are often caused by loss of habitat, due to agricultural, industrial or urban growth. The Bali and Javan subspecies of tiger both had relatively small populations to begin with, given the limited range of their island homes. As human population swelled in Indonesia throughout the 20th century, the habitat area of both tigers was severely depleted. In 1937, the Bali tiger was declared extinct. Some attempts to preserve the Javan tiger were made, but the last known survivor of the species died in 1980s.
Human-caused pollution is also considered a major cause of extinct animal species. In 2006, the Chinese river dolphin, also called the baiji, was declared to be in all probability extinct, after an exhaustive survey by Chinese biologists. The baiji, a freshwater dolphin that lived exclusively in the Yangtze river, is believed to have been unable to adapt to commercial use of the river and rising pollution levels.
In North America, recent estimates show 37 extinct animal species throughout the continent, all of them within the last 500 years. The Eastern population of North American cougar is believed to have been hunted to extinction in the early 20th century. Several species of gopher, including the Goff’s pocket gopher and Tacoma pocket gopher are listed by the International Union for the Conservation of Nature (IUCN) as extinct animal species due to habitat loss and hunting as pests by farmers and ranchers. The east coast and North Atlantic Ocean sea mink and Falkland fox were hunted to extinction for their pelts in the 19th century.
The list of extinct animal species compiled by IUCN is added to every year, and is maintained by the organization alongside lists of critically endangered or threatened species. If you wish to aid conservation efforts, many organizations exist devoted to research and maintenance of threatened animal populations. The use of biodegradable and environmentally-friendly consumer products can also help promote responsible use of resources by humans by lowering pollution rates and encouraging sustainable practices worldwide.