Assertion: tern's egg | /r/HasProperty | incubated by sex
Facets:
value: for 21 days
type: TEMPORAL
Source sentences:
text: Eggs are commonly laid in clutches of 2 from late May through June, and are incubated by both sexes for 21 days.
text: This egg is incubated by both sexes for 33 to 36 days, with each parent incubating for one or two days while their mate is feeding at sea.