Jul 172017

Tropical forest logging has contributed to population declines in many animals, including the Bornean gibbon, known for its whooping call. (Image credit: Gerardo Ceballos)

In the first such global evaluation, Stanford biologists found more than 30 percent of all vertebrates have declining populations. They call for curbs on the basic drivers of these losses. See video here.

No bells tolled when the last Catarina pupfish on Earth died. Newspapers didn’t carry the story when the Christmas Island pipistrelle vanished forever.

Two vertebrate species go extinct every year on average, but few people notice, perhaps because the rate seems relatively slow – not a clear and present threat to the natural systems we depend on. This view overlooks trends of extreme decline in animal populations, which tell a more dire story with cascading consequences, according to a new study that provides the first global evaluation of these population trends.

“This is the case of a biological annihilation occurring globally, even if the species these populations belong to are still present somewhere on Earth,” said co-author Rodolfo Dirzo, a professor of biology.

Mapping loss

A 2015 study co-authored by Paul Ehrlich, professor emeritus of biology, and colleagues showed that Earth has entered an era of mass extinction unparalleled since the dinosaurs died out 66 million years ago. The specter of extinction hangs over about 41 percent of all amphibian species and 26 percent of all mammals, according to the International Union for Conservation of Nature (IUCN), which maintains a list of threatened and extinct species. This global disaster scene has the fingerprints of habitat loss, overexploitation, invasive organisms, pollution, toxification and climate change.

The new analysis, published in Proceedings of the National Academy of Sciences, looks beyond species extinctions to provide a clear picture of dwindling populations and ranges. The researchers mapped the ranges of 27,600 species of birds, amphibians, mammals and reptiles – a sample representing nearly half of known terrestrial vertebrate species – and analyzed population losses in a sample of 177 well-studied mammal species between 1990 and 2015.

Using range reduction as a proxy for population loss, the study finds more than 30 percent of vertebrate species are declining in population size and range. Of the 177 mammals for which the researchers had detailed data, all have lost 30 percent or more of their geographic ranges and more than 40 percent have lost more than 80 percent of their ranges. Tropical regions have had the greatest number of decreasing species while temperate regions have seen similar or higher proportions of decreasing species. Particularly hard hit have been the mammals of south and southeast Asia, where all the large-bodied species of mammals analyzed have lost more than 80 percent of their geographic ranges.

The study’s maps suggest that as much as 50 percent of the number of animal individuals that once shared Earth have disappeared, as have billions of animal populations. This amounts to “a massive erosion of the greatest biological diversity in the history of Earth,” the authors write.

“The massive loss of populations and species reflects our lack of empathy to all the wild species that have been our companions since our origins,” said the new study’s lead author, Gerardo Ceballos of the National Autonomous University of Mexico. “It is a prelude to the disappearance of many more species and the decline of natural systems that make civilization possible.”

Cascading effects

Why does the loss of populations and biological diversity matter? Aside from being what the scientists call a prelude to species extinction, the losses rob us of crucial ecosystem services such as honeybees’ crop pollination, pest control and wetlands’ water purification. We also lose intricate ecological networks involving animals, plants and microorganisms – leading to less resilient ecosystems and pools of genetic information that may prove vital to species’ survival in a rapidly changing global environment.

“Sadly, our descendants will also have to do without the aesthetic pleasures and sources of imagination provided by our only known living counterparts in the universe,” said Ehrlich.

In the meantime, the overall scope of population losses makes clear the world cannot wait to address biodiversity damage, according to the authors. They call for curbs on the basic drivers of extinction – human overpopulation and overconsumption – and challenge society to move away from “the fiction that perpetual growth can occur on a finite planet.”

Learn more:Prelude to global extinction: Stanford biologists say disappearance of species tells only part of the story of human impact on Earth’s animals


The Latest on: Human impact on Earth’s animals
  • A Close-Up on Mysteries Made of Stone in Saudi Arabia’s Desert
    on November 19, 2017 at 3:14 am

    With Google Earth’s satellite imagery at his fingertips ... Sometimes multiple kites would overlap, so that if the animals got past one funnel they would get caught in another. “Essentially there was no escape,” said Dr. Kennedy. […]

  • What Happened To The Animals That Were Sent Into Space?
    on November 17, 2017 at 5:18 am

    A lot of animals have been to space, including dogs, monkeys, tortoises, and even a cat. But while some had a rather harrowing experience, others survived their missions and had a relatively normal life back on Earth ... and died on impact after re ... […]

  • Unexpected friendships between animals and their humans
    on November 17, 2017 at 4:11 am

    She chooses a location that might yield an interesting interaction and show the animal’s connection to the world of the humans who care for them ... A photographer selects images that visualize the impact of climate change In Sight is The Washington ... […]

  • Has Pope Francis violated the 8th Commandment, speaking out against climate skeptics?
    on November 17, 2017 at 12:00 am

    But at no time in Earth's history has the temperature increased ... Meanwhile, human activity is increasing, and natural plant and animal habitats are disappearing. The impact on human populations is significant and more detrimental than beneficial. […]

  • The Literary Work Asking What It Means to Be a Body on Earth
    on November 14, 2017 at 4:00 pm

    In their thesis, the authors ask their readers to consider the beavers not as an invasion, but as an animal diaspora ... Her objective isn’t just for us to see human impact on the planet, but to know what it is to live within scales of reality. […]

  • Stunning new photos show the faces of animals on the verge of extinction
    on November 14, 2017 at 1:30 am

    Photographer Tim Flach is renowned for his photos that show the emotional — or human — side of animals ... Jonathan Baillie and tries to make readers consider the impact they have on these animals — and consider what it would mean for them to ... […]

  • Dinosaurs extinct because asteroid hit the wrong spot on Earth, scientists say
    on November 11, 2017 at 12:01 pm

    Dinosaurs might still be roaming the Earth if the ... about 75% of animals were extinct, including nearly all dinosaurs. In 2014, the Edinburgh University paleontologist Steve Brusatte said dinosaurs might have survived the impact "if it had hit a few ... […]

  • Biologists say disappearance of species tells only part of the story of human impact on Earth's animals
    on July 10, 2017 at 12:01 pm

    Tropical forest logging has contributed to population declines in many animals, including the Bornean gibbon, known for its whooping call. Credit: Gerardo Ceballos No bells tolled when the last Catarina pupfish on Earth died. Newspapers didn't carry the ... […]

  • Maps Show Humans’ Growing Impact on the Planet
    on August 23, 2016 at 4:01 am

    The impact humans have on the environment has grown substantially in the last 16 years—so much so that a new study concludes three-quarters of Earth’s land surface ... with the highest diversity of plant and animal life. It’s become clear that ... […]

  • Humans Now Drive Evolution on Earth, both Creating and Destroying Species
    on July 5, 2016 at 11:31 am

    When scientists examine the impact ... that humans, through animal domestication, relocation and hunting, have become an evolutionary driving force that has led to new species, new traits and novel ecosystems. Look at humans’ effects on Earth’s plant ... […]

via Google News and Bing News

Other Interesting Posts

Leave a Reply

%d bloggers like this: