(As opposed to shapeshifting writers, who are a different and rarer creature.)
With mammals, you can tell pretty much immediately whether a shapeshifted individual is male or female.
With raptors and other predatory birds, not so much. (Unless you’re really good at picking up on differences in size even when looking at individuals in isolation. And for some species, not even then.)
There is surely a great deal of fascinating fictional exploration of gender and expectations to be had here, along with a fair amount of more straightforward gender-bending fun.
Though as with so many things, perhaps someone’s already written a manga about that? 🙂