I‘m not sure if they factored in the massive GPS jamming and spoofing going on in a war zone?
I pictured eagles consulting google maps to find their way before I realized that some eagles have GPS tracking devices put on them.
Dunno, but it's definitely something to consider. Birds are suspected to be able to "see" magnetic fields, and a lot of the electronic warfare both sides are waging require distorting these fields to a massive degree. If a bird can sense a huge cluster of warping magnetic anomalies it will avoid it, as we've seen them do in the past with radio telescope arrays and over-the-air TV antenna towers.