I can't pretend that I got involved with filming the natural world fifty years ago because I had some great banner to carry about conservation - not at all, I always had a huge pleasure in just watching the natural world and seeing what happens. - I made those films because it was a hugely enjoyable thing to do. But as I went on making them it became more and more apparent that the creatures that were giving me so much joy were under threat. The fun is in delighting in the animals but if you do that you owe them something so you have an obligation to speak out and to do what you can to protect them.

How Many People Can Live on Planet Earth? (BBC Horizon, 2009)