Assertion: hummingbird's migration | /r/HasProperty | challenge
Facets:
value: for hummingbirds
type: TRANSITIVE-OBJECT
value: for the ruby-throats
type: TRANSITIVE-OBJECT
value: always
type: DEGREE
Source sentences:
text: Migration is always a challenge for hummingbirds, who must fly huge distances to live in an environment that is warm and has a plentiful food supply.
text: Migration is quite a challenge for the hummingbird, especially for the ruby-throats, which may travel 2,500 miles from Alaska to Mexico and fly nonstop across the Gulf of Mexico.