Little birds talk with their sisters and brothers in their nest*. They make a sound for food. Mum tells them to be quiet when danger comes. But now a new study finds that kind of talk begins long before the babies are born. Even in the eggs, they can talk with each other and know when to get out or when to keep waiting.
To check that finding, a team of scientists from Spain watched unborn birds carefully in Salvora Island. Over there, sea birds produce eggs and minks* eat baby birds. So it is quite a dangerous place for baby birds. Knowing when to come out of the egg is a matter of life and death.
Scientists collected sea bird eggs and put them into two groups. When minks come, a parent will give warning calls to the baby birds. Scientists played those calls for one group. While the other group stayed in a safe box. They would never hear such calls.
When scientists put all the eggs together, they found something surprising: after receiving warning calls, the eggs vibrated* more than the others. Those vibrations moved from one egg to another. It was just like there were ears in the eggs. It was clear that unborn birds talked with their sisters and brothers about danger.
