There is no question that climate change is happening; the only arguable point is what part humans are playing in it.

I just wish the world was twice as big and half of it was still unexplored.

What I am interested in with birds, just as I am with spiders or monkeys, is what they do and why they do it.

The only acceptable way to solve ecological problems is if you can persuade people to have fewer children. In the Victorian times, there were families of 15 children. Someone like Edward Lear, he was the last of 21 children. And so what we have to think about is offering people the alternative choice. And in the West, that's what's happening. The birth rate has been dropping steadily and still is. I'm wanting human beings to be better off so they don't view children as an insurance for the future.

We really need to kick the carbon habit and stop making our energy from burning things. Climate change is also really important. You can wreck one rainforest then move, drain one area of resources and move onto another, but climate change is global.

The question is, are we happy to suppose that our grandchildren may never be able to see an elephant except in a picture book?

I have no doubt that the fundamental problem the planet faces is the enormous increase in the human population