"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."