bird dog vs chaperone

bird dog

verb
  • To seek out. 

  • A multiservice tactical brevity code requesting configuration of sensors. 

  • To watch closely. 

noun
  • A dog, especially a pointer, used in shooting to retrieve the dead birds. 

  • A tout. 

  • A person who seeks out real estate investment opportunities in exchange for a fee. 

  • A person who tries to steal someone else's romantic partner 

  • A radar detector (for detecting police speed traps). 

  • A hyperextension exercise performed lying on the knees, with one arm and the opposite leg lifted. 

chaperone

verb
  • To act as a chaperone. 

  • To work as a chaperone. 

noun
  • An older person who accompanies other younger people to ensure the propriety of their behaviour, often an older woman accompanying a young woman. 

  • A protein that assists the non-covalent folding/unfolding and the assembly/disassembly of other macromolecular structures, but does not occur in these structures when the latter are performing their normal biological functions. 

  • An employee sent by a British company to the European Union to work with a client there, to circumvent restrictions imposed after Brexit. 

How often have the words bird dog and chaperone occurred in a corpus of books? (source: Google Ngram Viewer )