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EarthSky // Earth, Science Wire Release Date: Jul 29, 2014

We’re in the early days of Earth’s sixth great extinction, say biologists

Since 1500, more than 320 land animals have gone extinct. Populations of the remaining species show a 25 percent average decline.

Photo credit: John Spooner/Flickr

Photo credit: John Spooner/Flickr

An international team of scientists cautions that the loss and decline of animals is contributing to what appears to be the early days of the planet’s sixth mass biological extinction event.

Since 1500, more than 320 terrestrial vertebrates have become extinct. Populations of the remaining species show a 25 percent average decline in abundance. The situation is similarly dire for invertebrate animal life.

And while previous extinctions have been driven by natural planetary transformations or catastrophic asteroid strikes, the current die-off can be associated to human activity, say the researchers.

Across vertebrates – animals with backbones – 16 to 33 percent of all species are estimated to be globally threatened or endangered. Large animals – including elephants, rhinoceroses, polar bears and countless other species worldwide – face the highest rate of decline.

Larger animals tend to have lower population growth rates and produce fewer offspring. They need larger habitat areas to maintain viable populations. Their size and meat mass make them easier and more attractive hunting targets for humans.

Invertebrates are in trouble as well, say the scientists. Human population has doubled in the past 35 years. In the same period, the number of invertebrate animals – such as beetles, butterflies, spiders and worms – has decreased by 45 percent.

As with larger animals, the loss is driven primarily by loss of habitat and global climate disruption.

The research is published in the journal Science.

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