This video from Canada says about itself:
22 November 2016
Here, an American Crow alights on the Ontario FeederWatch Platform feeder to join another. The latecomer makes a rattle call immediately after arriving. While scientists aren’t sure of this call’s meaning, they speculate it may be a way that crows communicate between family members .
This video from Georgia in the USA says about itself:
The familiar “caw” of the American Crow is a sound that is familiar to most of us that can be heard year-round. This is the most common call of the American Crow – a bird that has an impressive repertoire. It’s thought that these caws are used for long-distance communication between family members as well as territorial advertisement.