Assertion: petrel's diet | /r/HasProperty | known owing
Facets:
value: to difficulties
type: CAUSE
value: poorly
type: DEGREE
Source sentences:
text: The diet of many storm petrels species is poorly known owing to difficulties in researching; overall the family is thought to concentrate on crustaceans.
text: The diet of many storm petrels species is poorly known owing to difficulties in researching; overall, the family is thought to concentrate on crustaceans.