Rubus occidentalis vs blackcap

Rubus occidentalis

blackcap

noun
  • A small Old World warbler, Eurasian blackcap (Sylvia atricapilla), which is mainly grey with a black crown. 

  • An apple roasted until black, to be served in a dish of boiled custard. 

  • Whitebark raspberry (Rubus leucodermis). 

How often have the words Rubus occidentalis and blackcap occurred in a corpus of books? (source: Google Ngram Viewer )