Hm......what about the possibility of them passing through areas where their wings pick up chemical weapons, toxins, poisonings and then by the time they get to other areas, they fall dead.
What about an area powdered with some chemical agent as the one that killed the Russian spy? The birds come in, pick up and
carry the toxin to other locations. No evidence trail, just
a terrorist attack of a chemical weapon. The contamination then is spread.
I would not be surprised to see occurrences of "weird" bird deaths as ploys are developed.
Check out Weather wars
Full time weather manipulation measured by and assisted with the seemingly ever present chemtrail program. This doesn’t change from day to day or even season to season.
Ops4 God Bless You ALL.