Some birds were already exchanging their white winter plumage for the mottled camouflage of summer, another sign that winter was over.
(Some birds; were exchanging; their white winter plumage; for the mottled camouflage of summer; T:already) (winter; was; over)
Some birds winter
were exchanging was
their white winter plumage for the mottled camouflage of summer T:already
over