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                    Humans Driving Massive Animal Extinction

   by 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 [1]Science.

   Co-author [2]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.

   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.

   ''

   "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.
     __________________________________________________________________

   [3]http://www.voanews.com/content/humans-driving-massive-animal-extinct
   ion/1965453.html

References

   1. http://www.sciencemag.org/lookup/doi/10.1126/science.1251817
   2. https://labs.eemb.ucsb.edu/young/hillary/
   3. http://www.voanews.com/content/humans-driving-massive-animal-extinction/1965453.html