The researchers studied more than 600 species of birds and mammals

Ambitious targets to halt the decline in nature may already be slipping out of reach, a study suggests.

Scientists say the effects of climate change and habitat loss on animal populations have been underestimated.

They say bringing back wildlife may take longer than expected and that unless we act now global biodiversity targets will be out of reach.

In December almost 200 countries agreed to halt the decline in nature by the end of the decade.