To be honest, my family’s owned four birds in the last two decades and we kind of invented their genders from whole cloth
We wanted to be sure so we’d know whether we should be concerned about egg binding, because if that happens you only have about a day to fix it before the bird dies and if you’ve assumed a female bird is a male you wouldn’t think to check that until it’s too late. There are also some things about the blood work that would turn up as regular for a breeding-age female bird but be an indicator of infection in a male bird. When we bought them they were supposedly a male/female pair (we weren’t interested in breeding them, that’s just how most breeders sell pigeons), but Coocy (the one we assumed to be female) turned out to be male. That meant either the breeder was mistake or Belzy was female with some problems that were making him not lay eggs and behave like an aggressive male, which would probably have to be addressed. So we paid for the second blood test just to be sure so we’d know what kind of medical things to be on the lookout for.