Gone: a look at extinction over the past decade

Jeremy Hance
mongabay.com
January 03, 2010



A survey of twelve species lost to extinction over the past ten years.

No one can say with any certainty how many species went extinct from 2000-2009. Because no one knows if the world's species number 3 million or 30 million, it is impossible to guess how many known species—let alone unknown—may have vanished recently. Species in tropical forests and the world's oceans are notoriously under-surveyed, leaving gaping holes where species can vanish taking all of their secrets—even knowledge of their existence—with them.

It is also difficult to know when a species is truly gone. Some species reappear after they were thought to be extinct for decades, sometimes even centuries. Officially, species are usually not considered "extinct" until ample time passes without a sighting, for example, fifty years. Still, with many biologists and conservationists warning that we are in the midst of a human-caused mass extinction which may prove even larger than the demise of the dinosaurs, it is important to recognize likely vanished species before we know for certain they are gone, if only to remind ourselves of our impact and our failures.

Scientists have announced a number of likely extinctions (as well as extinctions in the wild) over the past ten years and here we look at twelve.





The baiji. Photo by Wang Ding and courtesy of the Institute of Hydrobiology, Chinese Academy of Sciences.
The Yangtze River, extinction hotspot: The most publicized extinction over the past decade is the baiji, also known as the Yangtze River Dolphin.

While the baiji's evolution goes back 20 million years, it couldn't survive China's great development boom. A combination of dams, boat traffic, pollution, overfishing, and electro-fishing led to the species demise giving the baiji the dubious title of the first marine mammal to go extinct since the 1950s. The dolphin was a character in Chinese myths and was colloquially known as the 'Yangtze River Goddess', but none of this could save it from an economic juggernaut.

But the baiji is not alone, another denizen of Yangtze may have vanished recently. A recent survey of the Chinese paddlefish, one of the world's largest freshwater fishes, failed to find even a single individual. While researchers believe the fish probably still survives, no one knows for certain—and no one knows how long it can persist in highly degraded habitat. The Chinese paddlefish has been decimated due to the same reasons as the baiji: dams, traffic, and pollution, although overfishing is probably the biggest cause. The last confirmed paddlefish was killed by illegal fishing in 2007.

Unless China acts quickly other species of the once fabled Yangtze will not survive the next decade, including the finless porpoise, the Yangtze sturgeon, and the Chinese alligator (although the alligator survives in large numbers in captivity).




The 'Alala. Photo by: US Fish and Wildlife Service.
A lesser Hawaii: Like the Yangtze river system, the Hawaiian islands—famous for unique birdlife—is an extinction hotspot.

In 2002 the 'Alala, also known as the Hawaiian crow, went extinct in the wild when the last two known individuals vanished. The bird suffered from a number of threats, including habitat loss, introduced rats, mongooses, and disease, as well as illegal collecting. The 'Alala was not the first: fossils show that four other crows have already gone extinct in Hawaii. But the 'Alala has long held a special place in Hawaiian culture: native Hawaiians considered the crow a household god.

Fortunately the last word has yet to be written for the 'Alala since over 50 individuals survive in captivity and the possibility of reintroduction is being discussed.

Another of Hawaii's birds is not so lucky: the Po'ouli or Black-faced honeycreeper went extinct in 2004. Unknown to science until the 1970s, the shy bird was endemic to the island of Maui alone. By the beginning of the decade only three individuals were known to survive. One died in captivity in 2004, the other two have not been seen since.


The Po'ouli. Photo by: US Fish and Wildlife Service.
While other Po'oulu could survive, no one knows for sure and it seems unlikely to find a healthy breeding population. Unlike the 'Alala reintroduction is an impossibility.

The birds are only the most recent representatives of a long decline in Hawaiian native species: half of Hawaii's 140 historically-recorded endemic bird species are gone forever.



Big Mammals No More: In addition to the baiji, the decade saw the extinction of two other large mammals.

In an ignoble end, the world's last Pyrenean ibex was killed by a fallen tree at the opening of the decade, January 6th, 2000. A subspecies of the Iberian ibex, the Pyrenean ibex once roamed across the Pyrenees in both France and Spain, but spent most of the Twentieth Century on the verge of extinction. Nine years after its extinction, the species returned for a moment: a clone of the subspecies was born—the first clone of an extinct animal—but died from lung failure after a few minutes.


Illustration of the Pyrenean ibex. Image from Cabrera, A. (1914).
The western black rhinoceros also met its end during this decade. Hunted relentlessly for its horn, the rhino went from thousands historically to ten individuals hanging on in Cameroon. By 2006, however, a survey found that none of the rhinos remained.

Rhinos are one of the world's most threatened big mammals: of the five remaining species, three are Critically Endangered, one is Endangered, and only the white rhino appears secure from extinction.

Poaching is behind the global decline in rhinos, and the end of this decade has seen poaching on the rise. Unless action is taken quickly to stop the illegal wildlife trade, it is not improbable that the next decade will see more rhino extinctions.

Amphibian Armageddon: The past few decades have been particularly perilous for amphibians. Devastated by a still-mysterious disease, the chytrid fungus, and hit by climate change, habitat loss, and pollution, the particularly-sensitive family of amphibians is in the midst of an extinction crisis.


The Kihansi spray toads mating in captivity. Photo by: Rhett A. Butler.
The Kihansi spray toad vanished from its home in the middle of the decade. Living adjacent to a waterfall and gorge in Tanzania, the toad survived on only two hectares of land, but when the World Bank built a dam in the area, the flow of the waterfall was changed and the toad could no longer thrive in the altered habitat. Surveys found fewer and fewer toads until they found none.

Like many amphibians that vanish from the wild, a population of Kihansi spray toads still survives in captivity in the United States. Reintroduction would only be possible if their native habitat can be made to support the toads again.

The Panamanian golden frog—a beautiful black and gold species—also likely vanished from the wild during the last years of the decade. A national symbol in Panama, the frog was devastated by the chytrid fungus and habitat destruction. Like the Kihansi spray toad, the Panamanian golden frog survives in captivity, but its future is hardly secure.

These are but a small representation: researchers estimate that more than 120 species of amphibians have likely gone extinct since 1980. With climate change scenarios growing increasingly dire, rampant deforestation, continuing pollution, and no cure yet to the chytrid fungus, it's unlikely the 2010s will be any better for amphibians.


The Panamanian golden frog with green infant. Photo by: Rhett A. Butler.
The Vanished Forgotten: While extinctions of mammals, birds, and amphibians garner the most media attention (in that order), invertebrates and plants are vanishing just as frequently.

Sometime between the end of the 1990s and during the beginning of this decade, the last Aldabra banded snail succumbed to desiccation. Little-known, this snail was endemic to the Aldabra atoll. Since the snail hibernates during dry periods, less rainfall over the Aldabra atoll due to global warming likely spelled its doom.

Another invertebrate lost to climate change is the European land leech. A survey between 2000-2005 found only a single living European land leech. The researchers believe that a rise of 3 degrees Celsius during the summertime has doomed the leech, which is adapted specifically to the cold.

Climate-sensitive species from polar bears to pikas to frogs to coral reefs are facing an uphill battle to survive in our warmer world. Extinctions due to climate change will likely become even more common in the next decade.


Illustration of the St. Helena olive. Drawing by: John Charles Meliss (1875).
Invertebrates are not the only little-known and often overlooked species. Plant extinctions—or discoveries for that matter—rarely make the news. In December 2003, the last St. Helena olive died in captivity. Prior to this, the species had vanished from the wild in 1994.

Endemic to St. Helena Island, the St. Helena olive perished from deforestation and the introduction of alien species like goats. No one knows how many plants have vanished during 2000-2009, but with high rates of rainforest destruction in many nations, it is likely that a large number of plants—many unknown to science—were lost in the last ten years.

Goodbye and maybe hope?: The last known wild Spix's macaw disappeared from Brazil in 2000. This beautiful macaw was battered by habitat loss and trapping for the pet trade. It is possible some wild macaws still remain, but more surveys are necessary. Still, even if no wild Spix's macaws remain, the species has a chance.

A small population of Spix's macaws survive in captivity and there has been recent success at reproduction, especially at Al Wabra Wildlife Preserve which has bred 21 birds since 2004. In addition, Al Wabra has purchased Spix's macaw habitat in Brazil for possible future reintroduction.

Spix's Macaw probably has the most hope of surviving the next ten years of any of these twelve. For the unfortunate others, this decade was their last stand.



List of (likely) extinct species, 2000-2009:

Baiji (Lipotes vexillifer)
Chinese paddlefish (Psephurus gladius)
'Alala (Corvus hawaiiensis)
Poo-uli (Melamprosops phaeosoma)
Pyrenean ibex (Capra pyrenaica pyrenaica)
Western black rhinocerous (Capra pyrenaica pyrenaica)
Kihansi Spray Toad (Nectophrynoides asperginis)
Panamanian golden frog (Atelopus zeteki)
Aldabra banded snail (Rachistia aldabrae)
The European land leech (Xerobdella lecomtei)





Illustration of Chinese paddlefish which can grow over 7 meters. Drawing by: Günther, Albert C. L. G. (1880).







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CITATION:
Jeremy Hance
mongabay.com (January 03, 2010).

Gone: a look at extinction over the past decade.

http://news.mongabay.com/2010/0103-hance_extinct.html