I wasn't that close to it to smell it. I'm thinking it was her letting go of her eggs. She's started sitting on her nest a couple of days ago. She's not letting the male mate with her anymore. I'm not sure how all that works because this is my first set of ducks and there first time nesting. I've been taking her eggs and incubating them myself. I had two hatch and two die. One of my babies has wry neck. I'm not feeling to great about my incubation. I tried chicks my first time and one made it out of 6. They start to pipe then nothing happens. Its like the shells to hard... I keep the temp. Around 99.5 to 100 and the humidity between 55 to 60. I live in south Texas. I have no idea what I'm doing wrong. I have 6 more duck eggs going into lock down on Sunday. I'm scared to have another failure. My momma duck seems to be doing great. She comes off her nest to eat drink and have her bath then she's right back to her nest..