jungle drums vs jungle telegraph

jungle drums

noun
  • An informal network of news and gossip; the grapevine. 

  • Drumming performed, or as performed, in the rituals of traditional pre-industrial societies. 

jungle telegraph

noun
  • A gossip network; an informal communication system within a group or organization. 

  • A system used by primitive cultures in remote tropical regions for communication over long distances, such as drum sounds or a relay of runners. 

How often have the words jungle drums and jungle telegraph occurred in a corpus of books? (source: Google Ngram Viewer )