dotterel vs not the sharpest knife in the drawer

dotterel

noun

  • A gullible fool, especially an elderly person with impaired faculties. 

  • A small brown-and-black bird, Charadrius morinellus, of the plover family. 

  • Any of various small birds of Australasia thought to resemble the Eurasian dotterel. 

adj

  • decayed 

not the sharpest knife in the drawer

noun

  • Lacking in intelligence; dimwitted. 

How often have the words dotterel and not the sharpest knife in the drawer occurred in a corpus of books? (source: Google Ngram Viewer )