Canuckbirdstrike, From your last paragraph -
The more likely cause is a classic escape maneuver and unless control test were conducted without radar there is no validity to the observation.
I've observed the classic escape maneuver (wings fully retracted, gravity assisted descent) on countless occasions in both radar equipped
AND non radar equipped aircraft. My observation is that it's most likely visual identification on their part, had a number of strikes from their rear end (ouch!), the evaders seem to have us in their line of sight. Hope that this helps.
This is a serious subject, but a bit of levity never hurts. At my old airline one of our F27 captains speared a poor duck straight up the bum with the rather long pitot tubes. Poor old Bluey (and the duck) never lived it down.
Canuckbirdstrike,keep up the very good work, thank you for your considerable efforts in making our crowded skies a little safer.