We've raised two ducks from one-day-old chicks. One was an Indian runner, the other a mallard. Both were males, and we've had them for five years. One week ago, the Indian runner died suddenly after suffering mucous discharge from his beak and diarrhea. We are wondering if we need to get more ducks to keep the mallard happy or if that would stress him. Since his buddy died, he has become less aggressive (before there was a lot of competition for my daughter whom they imprinted on). Now, he dabbles or rests near the house when allowed to roam. We have a limited size yard and can't accommodate a large flock. Both ducks were kept in a 12x8 ft enclosure w. large kiddie pool, fed cracked corn, and allowed to dabble for one to three hours a day. At night we put them in a large dog kennel for extra protection against predators.