Kyle Boatright wrote:

The second bird encounter was with a formation of a dozen or so ducks. We
were over Alabama at 11,500' headed NE and the ducks were probably at
11,300' headed South. They were flapping like mad, which isn't a surprise
given the altitude and their wing loading. Somehow, Flight Following missed
giving us the traffic warning. ;-) I told Kelly that if we'd hit the
ducks, it would have made a real ducking mess...

They obviously weren't squawking any code...