A question on Birds

Today's point to ponder: can birds fly and have a baby(egg) at the same time? I ask this because one of our birds was acting strange today and doesn't look like it can fly. And when i walked up to the cage-the one did the usual squaking and flying but the other just sat and looked at me. I decided hey-look at the other side of the bird since nothing looked odd from the front. Okay, i don't normally look at the backside of a bird-but it didn't look what i considered normal. So, it led me to think it may be laying an egg. It's now at the bottom of the cage and i think until it lays, it's stuck there-doesn't seem like it can fly-odd i think. Guess i know now which one laid the last egg and which one is the girl. :)