Assertion: swan's number | /r/HasProperty | declining in the west of its range
Facets:
value: since the late 19th century
type: TEMPORAL
value: slowly
type: MANNER
Source sentences:
text: Its numbers seem to be slowly declining in the west of its range since the late 19th century, coincident with the expansion of human settlement and habitat conversion in the birds' wintering areas; the eastern Whistling Swan populations on the other hand seem to be increasing somewhat, and altogether its numbers seem to have slightly risen in the late 20th century