You've heard pregnant women talk about nesting, whether that's painting the nursery, or cleaning the house from top to bottom before their baby arrives. But new research turns 'nesting' on its head.
Birds spend a lot of time and energy singing, but they don't do it the same way in every season of the year. And some can't sing at all. What's the purpose of birdsong?
We need to understand what a swallow's nest is really for – and it is not mainly for sleeping.