We had two male swans on our 8 acre lake and they live there peacefully for over 5 years. Two weeks ago we witnessed for the first time the swans fighting. We were afraid the dominate male was going to kill the other swan. We were finally able to break up the fight and for several days the swans, who usually stayed close together, were on opposite sides of the lake. After a week they appeared to be back to normal. Today we discovered one swan was gone and unable to find the swan. Could the dominate male have killed the swan? Also is it recommended to always have more than 1 swan?