a ready food source were most plentiful, the birds on the mainland were out of sync.
(the birds on the mainland; were; out of sync) Context(the birds on the mainland were,List([41, 71))):(a ready food source; were; most plentiful)
the birds on the mainland were,List([41, 71))
the birds on the mainland a ready food source
were were
out of sync
most plentiful