An Etymological Dictionary of the German Language/Annotated/schnattern

by Friedrich Kluge

schnattern, verb, ‘cackle, gabble, chatter,’ from Middle High German snateren, ‘to cackle, croak (of frogs), clatter (of storks), chatter’; compare Dutch snater, ‘beak,’ snateren, ‘to chatter, boast.’ The stem is not found elsewhere.