reflection aggression?

[cwatkins]

I have a bangaii cardinal that does this when the glass is freshly cleaned. If there is a buildup of film, then he doesn't.

So I think to some degree they see something. What that something is, is anyone's guess. Maybe a slight reflection like when you look in your rear view mirror in night mode? You see your back seat but you also see a bit of the road behind you...

Anyways, if it was fully reflective, they wouldn't see you coming and swim up to see you...