How did you find out your animals were male? With Bela, I didn't find out till the following year...when he got his adult feathers and his beak turned yellow in spring. Male starlings have some blue at the base of their beaks and females have pink. The females also have an extra ring around their eyes.
Of course it's not always certain but for the most part, that observation is pretty accurate. I'd have to send in a sample of his feathers for analysis to be 100% sure. Then I'd actually have to rip out a few of his chest feathers...ones that fall out naturally won't work. Besides, I don't really care that much. And so by the time I figured out he was a boy, he was already telling me 100 times a day that "I'm Bella! Bella's such a pretty bird!"