Its been around an hour and a half and the duckling was doing well in the incubator. We made the decision to return it to the nest. It was not dried off yet and it is in the 60's outside, so I hope she took it in, but it just seemed like the right thing to do (for numerous reasons). My wife helped, I carried the duckling out, it was peeping the whole way, we opened the duck house and Miss Ruby hissed at us at first (poor thing, disturbing her at 10:45 at night in the dark...) I put the new duckling on the bedding right next to her and she sniffed at it. Then she stepped off the nest (the baby couldn't even fully stand on its own yet) so I reached in and put the baby in the nest. Through all of that she had stopped hissing and was just watching. We stepped back and she got back on the nest with the new baby underneath her.
I hope that the duckling is ok and makes it, but through all of this I have been blown away by her mothering instinct as well as her seeming understanding that I am there to help. She still hisses at me and doesn't let me get close to the ducklings, but in the two instances where she needed me (taking the half hatched duckling and returning it) she didn't hiss or bite, she calmly moved aside and gave nice, calm, quiet quacks as if to thank me.
I know everyone on here views their birds differently, for us they are livestock. We enjoy them, take care of them, and do our best to give them a comfortable and good life, but at the end of the day they are also a source of eggs and meat. Of the seven ducklings, the plan is to keep the hens and butcher the drakes at 7-8 weeks. Butchering is never easy, and I always say a prayer and thank the duck for its gift of life for us, but I have to say, after this experience tonight, butchering will be more difficult this time than any other...
Thanks again for all your assistance, the advice and care on this forum is invaluable.