Co-ordinating Departure

When a lorikeet pair are feeding, and one of them wants to leave, it utters a very brief "whit" sound.  If the second bird doesn't react, the first bird continues the same call at regular intervals until the second bird reacts and they fly off together.  In terms of Halliday's model of protolanguage, this is an instance of the regulatory microfunction: 'I want + you-&-me'.