A name used for a female (or groups of females when plural) who talks a lot about nothing substantial and is not really interested in making conversation (or what another person has to say) but just blathering on about nothing. It is not meant to be a derrogatory term.
A group of females conversing chaotically can actually sound like a bunch of chickens making noise. It can be impossible to decipher any one phrase from the conversation since they are constantly interrupting eachother and changing subjects.
"I'm sorry? I can't really hear you over the chickenheads back there..."