A picture would help. But this is what I can tell you. Just before chicks or ducks hatch, they absorb the yolk, but often times the hole where their "belly button" will be is not always closed up, and usually it is attached to the membrane sac by a "umbillcal cord". In most cases, this all goes normally, the yolk is totally absorbed and the cord snaps naturally. Unfortunately, sometimes this cord gets hung up on something and that opening in the belly is not all the way closed, and sometimes a chick can be disembowled. I don't think thats whats happening to your bird, so don't freak. I am just trying to inform you of the possible complications. So, is the bird bloody around the navel, or bleeding? Is the navel open, or is anything (besides a thin cord) hanging out? If you think anything serious is going on, put the baby in a box or tupperware that fits into the incubator, and line it with a paper towel. If the egg is still attached by the cord, leave it attached and put it in with the duckling. Isolating the baby minimizes problems like the "disembowlment" I talked about earlier. If the chick is already seperated from the egg shell, meaning the cord is broke, and as long as no insides are hanging outside, you may leave the chick alone and just observe.