A new report shows the number of wild animals on earth has halved in the past 40 years.

The research by the Zoological Society of London and WWF says species across land, rivers and seas are being decimated as humans destroy habitats.

Professor Ken Norris from the Zoological Society of London told Newstalk ZB's Rachel Smalley it's due to a range of different human impacts on the planet.

"A loss of natural habitats, conversion of things like forests into agricultural land use and overexploitation of particular species for food."