Assertion: hummingbird | /r/HasAspect | an oil gland
Facets:
value: on their back
type: LOCATION
value: close to their tail
type: LOCATION
Source sentences:
text: They have an oil gland on their back, close to their tail, that they use to cover their wings with by using their beak.
text: On the back of their body near their tail, they have an oil gland.