If my grandchildren were to look at me and say, 'You were aware species were disappearing and you did nothing, you said nothing', that I think is culpable. I don't know how much more they expect me to be doing, I'd better ask them.

It's coming home to roost over the next 50 years or so. It's not just climate change; it's sheer space, places to grow food for this enormous horde. Either we limit our population growth or the natural world will do it for us, and the natural world is doing it for us right now.

People talk about doom-laden scenarios happening in the future: they are happening in Africa now. You can see it perfectly clearly. Periodic famines are due to too many people living on land that can't sustain them.

Steve Irwin did wonderful conservation work but I was uncomfortable about some of his stunts. Even if animals aren't aware that you are not treating them with respect, the viewers are.

An understanding of the natural world and what's in it is a source of not only a great curiosity but great fulfillment...

Birds were flying from continent to continent long before we were. They reached the coldest place on Earth, Antarctica, long before we did. They can survive in the hottest of deserts. Some can remain on the wing for years at a time. They can girdle the globe. Now, we have taken over the earth and the sea and the sky, but with skill and care and knowledge, we can ensure that there is still a place on Earth for birds in all their beauty and variety - if we want to... And surely, we should.

You'll discover in countries where women have control over their own bodies, where they have education, where they have birth control, where they have facilities and where they are literate, when those things happen, the birth rate falls.