Unhatched birds can warn others of danger by vibrating shells

Study finds developing chicks communicate with siblings when they hearalarm calls

Baby seabirds that have not yet hatched communicate with their siblings in neighbouring eggs by vibrating their shells, scientists have discovered.

A study of yellow-legged gulls revealed one of the most sophisticated known examples of embryonic communication. When exposed to the alarm calls of an adult bird responding to a predator, developing chicks apparently were able to convey the presence of danger to their nestmates by wriggling inside their eggs.