endangered vs guarded

endangered

adj
  • in danger, at risk, said of something where there is a strong possibility something bad will happen to it (for example, a species in danger of going extinct) 

guarded

adj
  • Cautious; restrained. 

  • Watched over; supervised. 

  • When the practitioner formulating the opinion does not have enough information to know, or to foretell, what the outcome may be. 

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