I love that "love rattle" noise they make! You are very lucky. As for the size, male crows tend to be slightly larger than females, but of course, that's no sure way to tell gender. You could have a paired couple made up of one smallish male and a largish female. Without doing a physical/medical inspection, the best way to tell the difference between female and male crows is to look at behavior rather than size. The males tend to be more assertive. They're often the ones to call loudly when they see me, the first to land on the street and swagger back and forth, waiting for me to throw the peanuts. The females hang back, sometimes even missing the chance to get a nut. Still, just as with people, I imagine these personality differences are not all gender-related, so ultimately the only way to tell a male from a female is with a physical inspection of their vents and bloodwork. Without that, all you can do is guess... and I would guess that the bigger, burbling one is the male.