Prince William says the rapid rise in human population numbers is having devastating consequences for the world.
The Duke of Cambridge, who is expecting his third child with wife Catherine, Duchess of Cambridge, told a Tusk Trust's gala dinner in London that the wildlife is under "enormous pressure" and called for measures to be put in place to minimise the damage caused by the growing population.
The prince's grandfather, the Duke of Edinburgh, advocated "voluntary family limitation" in 2011, to try to solve overpopulation.
"In my lifetime, we have seen global wildlife populations decline by over half," Prince William said at the gala dinner.
"We are going to have to work much harder, and think much deeper, if we are to ensure that human beings and the other species of animal with which we share this planet can continue to co-exist.