Hi, welcome to BYC! The eggs are most likely chilled if a day has past and they set over night, I think they probably were Mallards. What color was the duck that got killed? If it was brown, it was the female, if it was grey with a green head with a small white ring around the neck it was the male. Most often the female setting on eggs gets killed. Feel the eggs. I bet they are cold. They should feel warmer than your hand if they are good but I'm guessing not good. You may want to dispose of them before they start stinking sometimes the smell is enough to gag a maggot but that usually takes a few days for them to get that bad. I hope this helps you.