Dicky bird

Children’s talk for a small bird dates from the late 18th century but the origin is obscure, perhaps echoic of the sounds that small birds make and occurs in various spellings dickey, dickie etc. It is also rhyming slang for word, dicky bird/word, as in “I won’t say a dicky bird” or “not a dicky bird” meaning not a word. This rhyming slang dates from c.1930.