Hi DJFlotek
I have just listened to the recording.,
The calls in the first 30 seconds are what I would regard as "feeding calls" or maybe proclaiming territory. Those calls are heard where the birds live in summer, and also when feeding in migration grounds (eg, Banksia heathlands, or coastal forests).
The flight calls on migration are quite different from the calls on that recording.
YFHEs make a quiet "chip, chip" call when migrating.
WNHE make a mewing call, when migrating.
The calls are quite distinctive (as Philip Veerman has suggested).
Both appear to serve as contact calls, not proclaiming territory (when migrating).