More than half the world's wildlife gone in 50 years

A new study by the World Wide Fund for Nature has found more than half the world's wildlife has been wiped out over the past 50 years.

Koala numbers are decreasing alarmingly Source: AAP

Scientists from around the world have collaborated to produce the Living Planet Index report, which found land-clearing played a big role in the overall drop in wildlife numbers. 

One species reported to be in grave danger is Australia's native koalas.