If someone were to post a graphic representation of the debris field, showing what ended up where, I'd be more confident about what did happen
I am going to say, due my experience, I'm sceptical that birdstrike(s) could cause that type of catastrophic failure to not only the motors, but also the airframe. Tails, wings, and motor mounts are constructed pretty robustly.
When there are aircraft crashes, the mjority of the plane stayts together until impact.
I can only recall a few that did not- O'Hare, when the motor mount failed, and a couple of bombed planes...
Not an authorative answer, by all means, but again, just color me sceptical
If it severes the tail section, the plane would becomes unstable and pitch, and roll violently. The wing section breaks off. I can see that happening. I do not think it was birds though. Maybe a sheet metal bucking bar or something like that. If it was birds, they will be able to tell that with no problem.