Okay, so the ducklings live outside now. In 2 days they will be 5 weeks old. I was playing with Waddles and holding her, when Puddles came over. Puddles rested her head on my lap, and started vibrating. In my duck book she says it is common MALE behavior, when they want to mate. Now I DO know she wasn't cold, because me and Waddles were keeping her warm, and we were under their brooding lamp. She would only vibrate if I pet her head after that. Now I'm not sure if this is regular adult duck behavior, or if SHE is a HE. I can post of video of her quacking, she quacked WAYYY earlier than Waddles (Waddles is still learning to quack) and she is loud like a female. Any ideas???