Conservation charity WWF has unveiled its latest Living Planet report, which shows that wildlife populations have declined globally by nearly three-quarters since 1970.
There have also been "bright spots" signs of recovery, including in the UK where otters, beavers, white tailed eagles and bluefin tuna have all staged comebacks, while captive breeding and reintroductions have helped European bison return from extinction in the wild to 10 countries in just over 50 years.
WWF said wildlife recovery can take place "remarkably quickly" with rapid action, but warned it would be a mistake to think conservation alone would enable a global recovery of nature.
Major shifts are needed in the energy, food and finance systems that are driving declines, the conservation charity said – with signs that positive "tipping points" are already under way in energy at least.
Figures from the Living Planet index analysis carried out with the Zoological Society of London as part of the report show wildlife populations worldwide declined by an average of 73 per cent between 1970 and 2022.
The assessment, which measures changes in the sizes of populations of 5,970 species of birds, fish, mammals, reptiles and amphibians, using methods ranging from camera traps and scat analysis to aerial surveys, also found that half of the studied populations were stable or increasing.
The report also details success stories, ranging from concerted conservation work leading to a 70 per cent increase in wild tiger numbers since 2010, to revivals in sea otters in North America, southern African elephants, green turtles, and Atlantic and Pacific bluefin tuna.
It shows "there's grounds for hope", according to WWF's chief scientific adviser Dr Mike Barrett, even though "nature remains in freefall" at the global scale.
Otters were pushed "right to the brink" of extinction in the UK but are now relatively common across the country while there have been successes with reintroductions of species that had been lost altogether including beavers and white-tailed eagles, Dr Barrett said.
He said: "These are examples of species that can recover, can be reintroduced and recover when we actually do the right thing, when the right policies, the right conservation measures, the right protections, are in place.
"But we have got to keep emphasising that these are bright spots against an overall picture that is still one of decline."
This decline is being driven by threats from climate change mainly caused by burning fossil fuels, to agriculture, which is the largest cause of habitat loss, and financial systems driving investment into activities that harm nature.
Dr Barrett said: "It's clear that global biodiversity loss is now widely recognised as an existential threat to economic stability and security and human wellbeing.
"Given the appalling damage that humanity has inflicted on the planet over many decades, it is a remarkable truth that we have still got a way out.
He warned that nature could not recover once negative "tipping points" are passed, such as the collapse of the world's warm water coral reefs.
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