Living on the bodies of mammals, oxpeckers manage to get quite a varied diet. A maggot here, a tick there, a little sip of blood, perhaps a little ta… - David Attenborough

There are some four million different kinds of animals and plants in the world. Four million different solutions to the problems of staying alive. This is the story of how a few of them came to be as they are.

Many of New Zealand's birds flew here from Australia fifteen hundred miles away across the sea to the west. They started to do so millions of years ago, and they are still doing so today... So, if you know Australian birds, you will recognise quite a lot, particularly those that are relatively recent arrivals.

No sooner has one been pushed out of the nest then a second will follow, until there is only one left. And that's what happens nearly always in a pelican's nest. That being the case, it seems rather inefficient, not to say heartless, that the pelican should always lay three eggs. But the reason is that it's partly an insurance policy, in case something terrible happens to one or two of the chicks, there's always a third left to carry on. And partly because, very rarely, when the fishing is very good, it is possible to raise more than one chick.