Wildlife populations have been halved in past 40 years

A new study has warned that wildlife populations around the world have dropped by more than half in the past 40 years.

According to the new Living Planet Index, populations of mammals, birds, reptiles, amphibians and fish have declined by an average of 52%.

The report blames human activity for the alarming drop in numbers, with habitats destroyed more quickly than they can be replaced.

Roger Harrabin reports.