street sweeper vs whitewing

street sweeper

noun
  • A machine used to sweep streets. 

  • A person who is employed to sweep streets, pavements, and gutters, keeping them clear of litter. 

whitewing

noun
  • A street sweeper. 

  • The chaffinch. 

  • The velvet scoter. 

How often have the words street sweeper and whitewing occurred in a corpus of books? (source: Google Ngram Viewer )