News / Science & Technology

Humans Driving Massive Animal Extinction

Long-term experiments on fenced-off plots of land in Kenya show the cascading impacts of large wildlife loss on other species and on ecosystem functions - such as disease control, fire, and photosynthesis. (Credit: Hillary Young)
Long-term experiments on fenced-off plots of land in Kenya show the cascading impacts of large wildlife loss on other species and on ecosystem functions - such as disease control, fire, and photosynthesis. (Credit: Hillary Young)
Rosanne Skirble

Earth is in the midst of its sixth mass extinction of animal species  -- the first to be caused by humans -- in the past half-billion years, setting off a downward spiral in the environment and human health, which will accelerate unless action is taken, according to a new report in Science.

Co-author Hillary Young studies what happens when the big animals disappear. In her field work in Central Kenya, the University of California Santa Barbara researcher documents changes in four-hectare parcels of land, fenced to keep out giraffes and zebras and elephants.  

“We can measure things like the abundance of vegetation, the abundance of rodents, and the prevalence of disease in the wildlife species that are left behind,” she said.

Rapid decline

Rather quickly the fenced parcels fill with grasses and shrubs, providing cover for rats which overwhelm the area and are vectors for human disease.  

Humans Driving Massive Animal Extinction
Humans Driving Massive Animal Extinctioni
|| 0:00:00
...    
🔇
X

Young and her colleagues have coined a new term for this pattern of animal species loss. They call it defaunation.  

“We have lost more than 25 percent of all the vertebrates in the world - this is the number of individual animals in the world - and probably more than 45 percent of the invertebrate animals in the world," she observed. "On an average year, we’re probably losing 11,000 to 58,000 animal species. That’s just shocking to think about.”    

Beetles, bugs and butterflys disappearing too

This loss is all the more surprising, Young says, because similar patterns are playing out across species worldwide.  

  • Large mammals such as the tapir are the first to disappear in human-modified ecosystems. (Mauro Galetti)
  • White-lipped peccaries used to be the dominant terrestrial mammals in South American rainforests. (Mauro Galetti)
  • Muriquis and other large primates are vanishing from tropical ecosystems. (Pedro Jordano)
  • Scientists are studying the effects of defaunation in tropical forests. (Mauro Galetti)
  • Aldabra giant tortoises, introduced to Round Island, Mauritius, as ecological replacements for the extinct Mauritian giant tortoises, eat the fast-growing invasive flora. (Christine Griffiths)
  • Aldabra giant tortoises being re-located to the offshore Mauritian island, Round Island, over 150 years after the native giant tortoises went extinct. (Christine Griffiths)
  • Coal burning power plants are the biggest source of carbon pollution, which is responsible for climate change, which is also driving animal decline.
  • A warmer climate brings changes to the flora and fauna as in this major tributary of the Amazon river in Brazil, which pushed water levels to new lows. 
  • Long-term experiments in central Kenya remove large wildlife, such as zebra and elephants, with high voltage electric fencing. The studies demonstrate strong cascading impacts of large wildlife loss on other species and on ecosystem functions - such as disease control, fire, and photosynthesis. (Duncan Kimuyu)
  • Defaunation is leading to declines in selective large mammals. Small mammals, such as mice (shown here, the broad headed mouse, Zelotomys hildagardae) benefit, and often cause nuisances to humans by vectoring diseases or destroying crops. (Lauren Helge)
  • The Maasia people in Kenya are an example of a community whose livelihood will likely be strongly impacted by continuing defaunation. (Jack Silange)

“We tend to think of extinction and species decline in the terms of giant pandas or polar bears, but what we find is that these small invertebrates - the beetles, the worms, the moths and the ladybugs - those animals are declining at rates that were equivalent if not greater than the large species,” she said.  

These are signs, Young says, that the sixth mass extinction is under way. The study affirms that humans are speeding it up by destroying wild lands and over-exploiting animals and resources. This, in turn, has triggered invasions of exotic species and climate change on a grand scale.

Animals protect vital human services

Young says conservation is not an esoteric luxury to keep wildlife around.

“Basic ecosystem functions like soil protection or water purification or carbon cycling to keep the soils rich and the atmosphere clean - all of those are services provided by animals, often these invertebrates that we don’t think about so much, but also the larger vertebrates," she said. "And what we find is that when we lose these animals, we see massive changes in these ecosystems, functions in the systems that are impacted.”

As species die off, Young warns that defaunation can permanently upset the trajectory of life on Earth.  She says that loss, if left unchecked, will become a driver of global change rather than a consequence of it.   

“It is going to exacerbate climate change [and] water stress. It is going to increase human poverty and social conflict. These are themselves going to lead to more wildlife declines, and it’s going to create a downward spiral and we’re going to lose the opportunity to halt this spiral,” she said.

Young says slowing this planetary nightmare will require political will. She says immediately addressing habitat loss and over-exploitation of animals and resources would help in the short term, but in the long run, global action to curb climate change is imperative.

You May Like

Australia-Cambodia Resettlement Agreement Raises Concerns

Agreement calls for Cambodia to accept refugees in return for $35 million in aid and reflects Australia’s harder line approach towards asylum seekers and refugees More

India Looks to Become Arms Supplier Instead of Buyer

US hopes India can become alternative to China for countries looking to buy weapons, but experts question growth potential of Indian arms industry More

Earth Day Concert, Rally in Washington

President Obama also took up the issue Saturday in his weekly address, saying there 'no greater threat to our planet than climate change' More

This forum has been closed.
Comment Sorting
Comments
     
by: Jeffrey Tischler from: Monterey, California
July 26, 2014 11:17 AM
Nary a word on human overpopulation being a root cause of the disaster. There is no fix without long term plans to lower human populations globally. I prefer natural attrition to famine and war.

by: Eric Mills from: Oakland, CA
July 25, 2014 6:32 PM
Homo sapiens - "wise" no, "clever" surely.

Recommended reading:

THE SIXTH EXTINCTION, by Elizabeth Kolbert (Holt & Co., NYC, 2012), a NY TIMES bestseller;

SPILLOVER: Animal Infections and the Next Human Pandemic, by David Quammen (Norton & co. NYC, 2012);

DEATH AT SEAWORLD, by David Kirby (St. Martin's Press, NYC, 2012).

As the bumper strip says, "We're not the only species on the planet, we just act like it." Sadly, methinks that global warming and human hubris will soon make all this moot.

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
Are Energy Needs Putting Thailand's Natural Beauty at Risk?i
X
Steve Sandford
April 17, 2015 12:50 AM
Thailand's appetite for more electricity has led to the construction of new dams along the Mekong River to the north and new coal plants near the country's famous beaches in the south. A proposed coal plant in a so-called "green zone" has touched off a debate. VOA's Steve Sandford reports.
Video

Video Are Energy Needs Putting Thailand's Natural Beauty at Risk?

Thailand's appetite for more electricity has led to the construction of new dams along the Mekong River to the north and new coal plants near the country's famous beaches in the south. A proposed coal plant in a so-called "green zone" has touched off a debate. VOA's Steve Sandford reports.
Video

Video Overwhelmed by Migrants, Italy Mulls Military Action to Stabilize Libya

Thousands more migrants have arrived on the southern shores of Italy from North Africa in the past two days. Authorities say they expect the total number of arrivals this year to far exceed previous levels, and the government has said military action in Libya might be necessary to stem the flow. VOA's Henry Ridgwell reports.
Video

Video Putin Accuses Kyiv of ‘Cutting Off’ Eastern Ukraine

Russian President Vladimir Putin, in his annual televised call-in program, again denied there were any Russian troops fighting in Ukraine. He also said the West was trying to ‘contain’ Russia with sanctions. Henry Ridgwell reports on reactions to the president’s four-hour TV appearance.
Video

Video Eye Contact Secures Dog's Place in Human Heart

Dogs serve in the military, work with police and assist the disabled, and have been by our side for thousands of years serving as companions and loyal friends. We love them. They love us in return. VOA’s Rosanne Skirble reports on a new study that looks at the bio-chemical bond that cements that human-canine connection.
Video

Video Ukrainian Volunteers Search for Bodies of Missing Soldiers

As the cease-fire becomes more fragile in eastern Ukraine, a team of volunteer body collectors travels to the small village of Savur Mohyla in the what pro-Russian separatists call the Donetsk Peoples Republic - to retrieve bodies of fallen Ukrainian servicemen from rebel-held territories. Adam Bailes traveled with the team and has this report.
Video

Video Xenophobic Violence Sweeps South Africa

South Africa, long a haven for African immigrants, has been experiencing the worst xenophobic violence in years, with at least five people killed and hundreds displaced in recent weeks. From Johannesburg, VOA’s Anita Powell brings us this report.
Video

Video Sierra Leone President Koroma Bemoans Ebola Impact on Economy

In an interview with VOA's Shaka Ssali on Wednesday, President Ernest Koroma said the outbreak undermined his government’s efforts to boost and restructure the economy after years of civil war.
Video

Video Protester Lands Gyrocopter on Capitol Lawn

A 61-year-old mailman from Florida landed a small aircraft on the Capitol lawn in Washington to bring attention to campaign finance reform and what he says is government corruption. Wednesday's incident was one in a string of security breaches on U.S. government property. Zlatica Hoke reports the gyrocopter landing violated a no-fly zone.
Video

Video Apollo 13, NASA's 'Successful Failure,' Remembered

The Apollo 13 mission in 1970 was supposed to be NASA's third manned trip to the moon, but it became much more. On the flight's 45th anniversary, astronauts and flight directors gathered at Chicago's Adler Planetarium to talk about how the aborted mission changed manned spaceflight and continues to influence space exploration today. VOA’s Kane Farabaugh reports.
Video

Video Badly Burned Ukrainian Boy Bravely Fights Back

A 9-year-old Ukrainian boy has returned to his native country after intensive treatment in the United States for life-threatening burns. Volodia Bubela, burned in a house fire almost a year ago, battled back at a Boston hospital, impressing doctors with his bravery. Faith Lapidus narrates this report from VOA's Tetiana Kharchenko.
Video

Video US Maternity Leave Benefits Much Less Than Many Countries

It was almost 20 years ago that representatives of 189 countries met at a UN conference in Beijing and adopted a plan of action to achieve gender equality around the world. Now, two decades later, the University of California Los Angeles World Policy Analysis Center has issued a report examining what the Beijing Platform for Action has achieved. From Los Angeles, Elizabeth Lee has more.
Video

Video Endangered Hawaiian Birds Get Second Chance

Of the world's nearly 9,900 bird species, 13 percent are threatened with extinction, according to BirdLife International. Among them are two Hawaiian honeycreepers - tiny birds that live in the forest canopy, and, as the name implies, survive on nectar from tropical flowers. Scientists at the San Diego Zoo report they have managed to hatch half a dozen of their chicks in captivity, raising hopes that the birds will flutter back from the brink of extinction. VOA’s George Putic reports.
Video

Video Exhibit Brings Renaissance Master Out of the Shadows

The National Gallery of Art in Washington has raised the curtain on one of the most intriguing painters of the High Renaissance. Mostly ignored after his death in the early 1500s, Italian master Piero di Cosimo is now claiming his place alongside the best-known artists of the period. VOA’s Ardita Dunellari reports.
Video

Video Sidemen to Famous Blues Artists Record Their Own CD

Legendary blues singer BB King was briefly hospitalized last week and the 87-year-old “King of the Blues” may not be touring much anymore. But some of the musicians who have played with him and other blues legends have now released their own CD in an attempt to pass the torch to younger fans... and put their own talents out front as well. VOA’s Greg Flakus has followed this project over the past year and filed this report from Houston.
Video

Video Iran-Saudi Rivalry Is Stoking Conflict in Yemen

Iran has proposed a peace plan to end the conflict in Yemen, but the idea has received little support from regional rivals like Saudi Arabia. They accuse Tehran of backing the Houthi rebels, who have forced Yemen’s president to flee to Riyadh, and have taken over swaths of Yemen. As Henry Ridgwell reports for VOA, analysts say the conflict is being fueled by the Sunni-Shia rivalry between the two regional powers.

VOA Blogs