[blam]

"Is it possible the birds were driven along that road, and they somehow have a way to simply retrace their route? Some sort of geographic memory system, maybe?"

Interesting. I hadn't considered that.

[DoughtyOne]

Interesting premise Semper911... It would be advisable for them to transport a variety of ways to the release point, then see how close to the delivery method they retraced.

Checking out the route shown this time, it's clear the birds tried to use the ramps. Were those the ramps the delivery truck used? They just may be.