Suzeman
The answer is quite obvious - the birds weren't squawking .....
Last night I spoke to a friend who flew out of CIA on Sunday.
She told her husband about a huge flock of starlings that were just below them (to the port) shortly after they'd flown over the airport boundary. I don't know which direction they took off in). She said she remarked to her husband she thought airports had bird scarers and thus started an inflight conversation about using birds of prey to keep flocks away.
She was quite shaken up when she saw the news last night.