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 most extraordinary thing about trying to piece together the missing links in the evolutionary story is that when you do find a missing link and put it in the story, you suddenly need all these other missing links to connect to the new discovery. The gaps and questions actually increase - it's extraordinary.

Climate change will affect the whole of humanity, while terrorist attacks will only affect a small section of humanity. Of course, you wouldn't say that if you were related to someone who had been beheaded or blown up or murdered. But humanity is facing a very big, slow, long, drawn-out threat, and that is to do with the way the weather is changing and the size of the population.

I've never actually met one in the wild, but I have seen a king cobra. They go towards people, they rear up six feet tall and they're very aggressive and they are very fast. And one bite means certain death. So if I encountered a king cobra in the wild I would be very alarmed.

If we were all to reduce our demands for energy, it would make an enormous amount of difference.

I'm no longer sceptical. I no longer have any doubt at all. I think climate change is the major challenge facing the world.

I'm luckier than my grandfather, who didn't move more than five miles from the village in which he was born.