The average animal will be 10 per cent smaller in the next century

The world’s animals are collectively shrinking, as humans drive big beasts such as elephants and tigers extinct, with far-reaching consequences for ecosystems.

Previous studies have shown bigger animals are at a greater risk of extinction and there is evidence humans have helped wiped out megafauna in the past, including woolly mammoths. Now an assessment of the next 100 years has found that habitat destruction, poaching and other human pressures will cause mammals and birds to experience “substantial ecological downsizing”.

Researchers ran a thousand scenarios on the future of the 15,500 species…