Assertion: cormorant's feather | /r/HasProperty | waterproof
Facets:
Source sentences:
text: Some sources state that cormorants have waterproof feathers while others say that they have water-permeable feathers.
text: Unlike many other waterbirds the feathers of the African darter do not contain any oil and are therefore not waterproof.
text: The feathers are waterproof, which allows the birds to spend long periods in water.