Extinction

Background: Extinction is the death of a species. Scientists recognize five historical mass extinction events in the past -- the Ordovician, the Devonian, the Permian, the Triassic and the Cretaceous -- and most would agree that we are currently in the midst of a sixth great extinction, the Holocene.

The Holocene extinction is the first extinction event directly caused by another species -- us. It results from habitat destruction combined with hunting and the introduction of alien species to environments where they do not occur naturally. Scientists estimate that extinction rates are presently 1,000-10,000 times the historical background rate of about 1 species per million per year. They say that extinction rates will significantly increase in coming years.

Articles

Syrian bald ibis may be down to a single bird
(06/11/2013) The eastern population of northern bald ibises (Geronticus eremita) has likely fallen to a single breeding bird, reports conservationists monitoring the dwindling flock. The population had believed to be obliterated starting from 1989 until a small group was discovered in 2002 in Syria. However, it now appears that this last group is vanishing one-by-one despite efforts by conservation groups to sustain the distinct population.

The comeback kids: the role of zoos in saving species from oblivion (photos)
(06/03/2013) While many people may view zoos first and foremost as attractions, these institutions have a long history of supporting and instigating conservation work, including saving species from extinction that have vanished from their wild habitat. But such efforts require not just dedication and patience, but herculean organizational efforts. Enter, the World Association of Zoos and Aquariums (WAZA), which works with zoos and aquariums to set up conservation programs and track endangered species in captivity.

Loss of big fruit-eating birds impacting trees in endangered rainforests
(05/31/2013) The extinction of large, fruit-eating birds in fragments of Brazil's Atlantic rainforest has caused palm trees to produce smaller seeds over the past century, impacting forest ecology, finds a study published in the journal Science.

Over 500 scientists warn we 'are causing alarming levels of harm to our planet'
(05/27/2013) A new consensus statement by 520 scientists from around the world warns that global environmental harm is putting at risk the happiness and well-being of this and future generations.

Plants re-grow after five centuries under the ice
(05/27/2013) While monitoring the retreat of the Teardrop Glacier in the Canadian Arctic, scientists have found that recently unfrozen plants, some of which had been under ice since the reign of Henry VIII, were capable of new growth.

Could the Tasmanian tiger be hiding out in New Guinea?
(05/20/2013) Many people still believe the Tasmanian tiger (Thylacinus cynocephalus) survives in the wilds of Tasmania, even though the species was declared extinct over eighty years ago. Sightings and reports of the elusive carnivorous marsupial, which was the top predator on the island, pop-up almost as frequently as those of Bigfoot in North America, but to date no definitive evidence has emerged of its survival. Yet, a noted cryptozoologist (one who searches for hidden animals), Dr. Karl Shuker, wrote recently that tiger hunters should perhaps turn their attention to a different island: New Guinea.

Aquarium launches desperate search to save a species down to 3 individuals
(05/10/2013) Aquarists at ZSL London Zoo have launched a worldwide appeal to find a female mate for a fish species that is believed to have gone extinct in the wild.

The Hawaiian silversword: another warning on climate change
(05/06/2013) The Hawaiian silversword (Argyroxyphium sandwicense), a beautiful, spiny plant from the volcanic Hawaiian highlands may not survive the ravages of climate change, according to a new study in Global Change Biology. An unmistakable plant, the silversword has long, sword-shaped leaves covered in silver hair and beautiful flowering stalks that may tower to a height of three meters.

13 year search for Taiwan's top predator comes up empty-handed
(05/01/2013) After 13 years of searching for the Formosan clouded leopard (Neofelis nebulosa brachyura), once hopeful scientists say they believe the cat is likely extinct. For more than a decade scientists set up over 1,500 camera traps and scent traps in the mountains of Taiwan where they believed the cat may still be hiding out, only to find nothing.

Rhinos now extinct in Mozambique's Limpopo National Park
(04/25/2013) Poachers have likely killed off the last rhinos in Mozambique's Limpopo National Park, according to a park official.

Featured video: time to meet The Lonely Dodo
(04/24/2013) A new short animation (see below) highlights the plight of today's most endangered species by focusing on one which is already extinct: the dodo. The animation, produced by Academy award-winning studio Aardman, introduces the world to the last, and very lonely, dodo. The short was created for conservation organization, the Durrell Wildlife Conservation Trust, which is striving to save a number of species from the dodo's fate.

Yangtze porpoise down to 1,000 animals as world's most degraded river may soon claim another extinction
(04/16/2013) A survey late last year found that the Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) population has been cut in half in just six years. During a 44-day survey, experts estimated 1,000 river porpoises inhabited the river and adjoining lakes, down from around 2,000 in 2006. The ecology of China's Yangtze River has been decimated the Three Gorges Dam, ship traffic, pollution, electrofishing, and overfishing, making it arguably the world's most degraded major river. These environmental tolls have already led to the likely extinction of the Yangtze river dolphin (Lipotes vexillifer), or baiji, and possibly the Chinese paddlefish (Psephurus gladius), which is one of the world's longest freshwater fish.

Future generations to pay for our mistakes: biodiversity loss doesn't appear for decades
(04/15/2013) The biodiversity of Europe today is largely linked to environmental conditions decades ago, according to a new large-scale study in the Proceedings of the National Academy of Sciences (PNAS). Looking at various social and economic conditions from the last hundred years, scientists found that today's European species were closely aligned to environmental impacts on the continent from 1900 and 1950 instead of more recent times. The findings imply that scientists may be underestimating the total decline in global biodiversity, while future generations will inherit a natural world of our making.

How many animals do we need to keep extinction at bay?
(04/15/2013) How many animal individuals are needed to ensure a species isn't doomed to extinction even with our best conservation efforts? While no one knows exactly, scientists have created complex models to attempt an answer. They call this important threshold the "minimum viable population" and have spilled plenty of ink trying to decipher estimates, many of which fall in the thousands. However, a new study in Conservation Biology shows that some long-lived animals may not need so many individuals to retain a stable population.

Humans killed over 10 percent of the world's bird species when they colonized the Pacific Islands
(03/25/2013) Around 4,000 years ago intrepid Polynesian seafarers made their way into an untamed wilderness: the far-flung Pacific Islands. Over a thousands or so years, they rowed from one island to another, stepping on shores never yet seen by humans. While this vast colonization brought about a new era of human history, it also ended the existence of well-over a thousand bird species according to a new study in the Proceedings of the National Academy of Sciences (PNAS).

Scientists clone extinct frog that births young from its mouth
(03/18/2013) Australian scientists have produced cloned embryos of an extinct species of frog known for its strange reproductive behavior, reports the University of New South Wales.

Seeing the forest through the elephants: slaughtered elephants taking rainforest trees with them
(03/11/2013) Elephants are vanishing. The booming illegal ivory trade is decimating the world's largest land animal, but no place has been harder hit than the Congo basin and its forest elephants (Loxodonta cyclotis). The numbers are staggering: a single park in Gabon, Minkebe National Park, has seen 11,100 forest elephants killed in the last eight years; Okapi Faunal Reserve in the Democratic Republic of the Congo has lost 75 percent of its elephants in fifteen years; and a new study in PLoS ONE estimates that in total 60 percent of the world's forest elephants have been killed in the last decade alone. But what does that mean for the Congo forest?

Starry frog rediscovered after thought extinct for 160 years (photos)
(03/07/2013) In 1853 Edward Frederick Kelaart, a physician and naturalist, collected a strange frog on the island of Sri Lanka then a British colony known as Ceylon. The specimen was a large shrub frog (about 2 inches or 5.5 centimeters long) with black-outlined white specks on lime-green skin. He dubbed it "starry" after its pale specks, but that was last anyone heard of it. Even the holotype—the body of the amphibian collected by Kelaart—went missing. Fast forward nearly 160 years—two world wars, Sri Lanka's independence, and a man on the moon—when a recent expedition into Sri Lanka's Peak Wilderness rediscovered a beguiling frog with pinkish specks.

Warnings of global ecological tipping points may be overstated
(03/05/2013) There's little evidence that the Earth is nearing a global ecological tipping point, according to a new Trends in Ecology and Evolution paper that is bound to be controversial. The authors argue that despite numerous warnings that the Earth is headed toward an ecological tipping point due to environmental stressors, such as habitat loss or climate change, it's unlikely this will occur anytime soon—at least not on land. The paper comes with a number of caveats, including that a global tipping point could occur in marine ecosystems due to ocean acidification from burning fossil fuels. In addition, regional tipping points, such as the Arctic ice melt or the Amazon rainforest drying out, are still of great concern.

Extinction warning: racing to save the little dodo from its cousin's fate
(03/04/2013) Sometime in the late 1600s the world's last dodo perished on the island of Mauritius. No one knows how it spent its final moments—rather in the grip of some invasive predator or simply fading away from loneliness—but with its passing came an icon of extinction, that final breath passed by the last of its kind. The dodo, a giant flightless pigeon, was a marvel of the animal world: now another island ground pigeon, known as the little dodo, is facing its namesake's fate. Found only in Samoa, composed of ten islands, the bird has many names: the tooth-billed pigeon, the Manumea (local name), and Didunculus ("little dodo") strigirostris, which lead one scientist to Christen it the Dodlet. But according to recent surveys without rapid action the Dodlet may soon be as extinct as the dodo.

Famous extinct animals

Birds

The Elephant bird (Aepyornis maximus) of Madagascar was hunted to extinction by humans after they arrived on the Indian Ocean island. The bird, which stood over three meters (10 feet) tall and weighed more than 500 kilograms (1100 pounds), disappeared in the 15th or 16th century. Its egg was about 160 times the size of a chicken egg. Reconstructed eggs are commonly sold in markets in Madagascar.

The black or King Island emu (Dromaius ater) of King Island (between Australia and Tasmania) was first discovered by western science in 1802. It was extinct by 1822. Hunting and fires set by visiting sailors caused its demise.

The Great Auk (Pinguinus impennis) was once found in great numbers on islands off eastern Canada, Greenland, Iceland, Norway, Ireland and Great Britain but was hunted to extinction by the mid-nineteenth century. The Great Auk was mostly hunted for its down.

The Passenger Pigeon (Ectopistes migratorius) may have one been the world's most abundant bird with a single flock reportedly numbering up to several billion birds. Hunting for sport and food lead to its rapid demise. The last wild Passenger Pigeon was shot by a 14-year-old boy in Ohio in 1900, while the last known individual of the passenger pigeon species, named "Martha" after Martha Washington, died at 1 p.m. on the 1st of September 1914 in the Cincinnati Zoological Garden. She was 29. Some scholars have argued that massive passenger pigeon flocks were the result of ecological imbalance caused by the massive decline in North American human populations following the arrival of Europeans in the 15th and 16th century. The theory holds that the disappearance of indigenous populations gave passenger pigeons an unprecedented opportunity to access resources previously appropriated by humans.

The Dodo (Raphus cucullatus) of Mauritius is perhaps history's most famous extinct bird. Hunting, coupled with widespread forest loss caused by Dutch settlers and their introduced animals killed off the last Dodo in 1681, within 80 years after the arrival of humans. The dodo bird was famously believed to be a key disperser of the Tambalacoque tree, seeds of which were said to require gut passage through the dodo in order to germinate. While this is a nice story, it's controversial.

Carolina Parakeet (Conuropsis carolinensis) was the only parrot species native to the eastern United States. Hunting and habitat loss due to forest conversion for agriculture led to its demise. The last wild specimen was killed in Okeechobee County in Florida in 1904, and the last captive bird died at the Cincinnati Zoo in 1918. The extinction of the Carolina Parakeet resulted in a boom of cocklebur, a common weed that was a favorite food of the bird..

The North American Ivory-billed Woodpecker (Campephilus principalis principalis) may or may not be extinct. The last confirmed sighting of North America's largest and most famous woodpecker is hotly debated. To date no conclusive evidence has been put forward to end the controversy. Regardless of its fate, the Ivory-billed Woodpecker's demise was fueled by destruction of its habitat -- hardwood swamps and pine forest in the southern United States -- due logging in the early part of the 20th century.

At least 15 species of Hawaiian honey creepers (various species) have gone extinct since the arrival of Polynesians. Often compared to Darwin's finches for their high degree of adaptation to ecological niches on the Hawaiian islands, honey creepers mostly died out as the result of introduced species, including rats and mosquitoes.

The Heath Hen (Tympanuchus cupido cupido) was hunted to extinction by European colonists who settled in North America. In fact some historians speculate that the first Thanksgiving featured Heath Hen, not turkey. The last heath hen was seen on March 11, 1932. Heath Hens were one of the first bird species that the United States sought to protect: in 1791 New York legislature introduced a bill to protect the species. Nevertheless, the effort eventually failed.

The Moa were giant flightless birds (15 known species) native to New Zealand. Peculiar for their total lack of wings, the largest species, the giant moa (Dinornis robustus and Dinornis novaezelandiae), reached 3.6 m (12 ft) in height and 250 kg (550 lb) in weight. They were the dominant herbivores in the New Zealand forest ecosystem and their disappearance a few hundred years after the arrival of Polynesians resulted in significant ecological change including the extinction of other species. Moa were doomed by forest clearing and hunting by the Polynesian invaders.

Mammals

Steller's Sea Cow (Hydrodamalis gigas) was a giant sea mammal that once roamed the Bering Sea in the North Pacific. The sea cow grew up to 7.9 meters (26 ft) long and weighed up to three tons. It was hunted to extinction by sailors and traders. The last known sea cow was seen in 1768.

The Thylacine or Tasmanian Tiger (Thylacinus cynocephalus) of Australia and New Guinea was the largest known carnivorous marsupial of modern times. The species went extinct through most of its range well prior to the arrival of Europeans, but managed to survive on the island of Tasmania until the mid-20th century. Disease, hunting, habitat destruction, and the introduction of dogs fueled its demise. While the last known Thylacine died at the Hobart Zoo in 1936, unconfirmed sightings continue today.

The Barbary Lion (Panthera leo leo) is a subspecies of lion that went extinct in the wild, though some descendants may survive in captivity. It was the largest subspecies of lion and lived in the woodlands in North Africa. Its demise stemmed primarily from hunting and habitat loss.

The Caribbean Monk Seal (Monachus tropicalis) was the only seal ever known to be native to the Caribbean sea and the Gulf of Mexico. It was last spotted in 1952 at Seranilla Bank, Jamaica. The Caribbean Monk Seal was said to lack fear of man, while having an unaggressive and curious nature -- attributes that likely contributed to its demise from habitat loss and hunting.

The lesser Puerto Rican Ground Sloth (Acratocnus odontrigonus) was one of the last remnants of the giant ground sloths that once dominated South America. The species was driven to extinction as recently as the 16th century due to the introduction of rats and pigs by Europeans explorers. Pre-Colombian populations likely diminished the populations of this 50-pound forest dwelling beast by forest clearing and hunting.

The Baiji or Yangtze river dolphin (Lipotes vexillifer) was declared functionally extinct in 2006 meaning that even if has not yet completely disappeared, its population is so low that it will never recover. The freshwater river dolphin was driven to extinction by pollution in the Yangtze and unsustainable fishing practices. The construction of the Three Gorges Dam and other hydroelectric projects also led to habitat loss.

The Bali tiger (Panthera tigris balica) of the Indonesian island of Bali was the smallest of three sub-species of tiger found in Indonesia. It was driven to extinction by conversion of its forest habitat for agriculture. The last tiger to be shot was in 1925.

The Javan tiger (Panthera tigris sondaica) was a tiger found only on the Indonesian island of Java. Highly threatened by hunting and habitat destruction, last minute efforts to create protected areas for the species during the 1950s and 1960s failed: the credible sighting was in 1972.

The Formosan Clouded Leopard (Neofelis nebulosa brachyura) was a subspecies of Clouded Leopard endemic to the island of Taiwan. It is now believed to be extinct due to habitat destruction by loggers.

Amphibians

Considered to be one of the most spectacularly colored toads on Earth with its brilliant yellow-orange coloring, the Golden toad is believed to be limited to only a single mountain in Costa Rica, Monteverde. Although always rare, for a few weeks in April every year, hundreds on these brilliant toads gathered in pools in a breeding orgy. However, the toad population dropped sharply since its discovery in 1967 from several thousand gathered in 1987 to just 10 in 1988, none of which were breeding. In 1989 only a single male toad, seeking a mate, was observed. This individual may have been the last Golden toad on Earth; no golden toads have been seen since. The disappearance of the golden toad is of particular significance since its habitat is in a national preserve.

Among the casualties of the current human-induced mass extinction event are the two species of Gastric Brooding Frog from the rainforest of Queensland, Australia: the Northern Gastric Brooding Frog (Rheobatrachus vitellinus) and the Gastric Brooding Frog (Rheobatrachus silus). These two recently discovered species [R. silus was discovered in 1972; R. vitellinus 1984] are presumed extinct as R. silus was last seen in the wild in September 1981 and R. vitellinus was last seen in March 1985. Gastric Brooding Frogs are notable for their reproductive habits. The female swallows her clutch of eggs and the tadpoles hatch in her stomach. The tadpoles secrete chemicals that cause the female to cease feeding and switch off the production of hydrochloric acid in the stomach wall. The young are birthed through the mother's mouth once fully developed as froglets. After leaving the mother's mouth, the young frogs are independent. Scientists have been interested in these species' ability to shut down the secretion of digestive acids the implications of which could have an important bearing in the treatment of people who suffer from gastric ulcers.

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