one of my 1 year old black runner ducks died this morning. She didn't come out of the coop this morning, her breathing was heavy and she just stood by her nest. I looked up her symptoms, figured she was egg bound, called to see if the vet could give her a calcium injection. When I went out to bring her in, she had already died. She must have been having trouble for a while, but I was out of town for a medical emergency with my dad and the kids were taking care of the ducks so I never had a chance to realize something was wrong until it was too late. 
Sorry for your loss. 
