bird dog vs shepherd

bird dog

verb
  • To watch closely. 

  • A multiservice tactical brevity code requesting configuration of sensors. 

  • To seek out. 

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. 

shepherd

verb
  • To watch over; to guide. 

  • To obstruct an opponent from getting to the ball, either when a teammate has it or is going for it, or if the ball is about to bounce through the goal or out of bounds. 

noun
  • A person who tends sheep, especially a grazing flock. 

  • Someone who watches over, looks after, or guides somebody. 

  • A swain; a rustic male lover. 

  • The pastor of a church; one who guides others in religion. 

  • A male sheep tender 

  • A German Shepherd. 

  • A male pastor 

  • A male watcher/guardian/guider/leader 

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