We have several male and female ducks that are laying eggs. One female and male couple started leaving in the morning and returning in the late evening, just before dark. Obviously she was laying eggs somewhere out in the woods beyond the pond, because there were no longer any of her eggs in the duck house. One day the male returned in the evening, casually, without the female and has never left during the day again. Do you think she is on a nest or was killed? It has been about 31 days since she disappeared.