The figures suggest that animals living in lakes, rivers and wetlands are suffering the biggest losses. Human activity, including habitat loss, wildlife trade, pollution and climate change contributed to the declines.
Dr Mike Barrett. head of science and policy at WWF, said: "It's pretty clear under 'business as usual' we will see continued declines in these wildlife populations. But I think now we've reached a point where there isn't really any excuse to let this carry on. "We know what the causes are and we know the scale of the impact that humans are having on nature and on wildlife populations - it really is now down to us to act."The BBC science writer notes that there are criticisms of the methods used in the report, since many parts of the world don't have good data on animal populations. But even taking those limits into account, the animal population is in decline, we are the cause, and this is not a good thing.