twig vs watch like a hawk

twig

verb
  • To observe slyly; also, to perceive; to discover. 

  • To twitch; 

  • To beat with twigs. 

  • To tweak. 

  • To realise something; to catch on; to recognize someone or something. 

  • To understand the meaning of (a person); to comprehend. 

noun
  • A small thin branch of a tree or bush. 

watch like a hawk

verb
  • To observe (someone or something) closely and keenly. 

How often have the words twig and watch like a hawk occurred in a corpus of books? (source: Google Ngram Viewer )