UK bluefin tuna comeback shows nature can recover, says WWF

But despite the individual successes, the overall picture for nature remains stark.

Working with the Zoological Society of London, WWF tracks nearly 36,000 populations of almost 6,000 species of mammals, birds, fish, reptiles and amphibians.

It estimates global monitored wildlife populations have fallen by an average of 73% since 1970.

The figure measures the average change in the size of those populations, not the number of animals lost. About half of the populations are stable or growing, but their gains are outweighed by losses elsewhere.

Dr Katie Collins, a senior curator at the Natural History Museum in London, also said the index misses out vast numbers of important species because it covers only vertebrates, missing plants, insects and other creatures they depend on.

“If you lose garden snails, you lose the song thrush,” she warned.