Is your weather pattern different this year, i.e, early heat, cold and then another heat wave, or vice versa? Black swans produce cygnets twice a year and if the weather has changed, they may think it is time to mate when in actuality it is not.

Most black swans are more aggressive than other swan species, so this is normal behavior. As for the food, the access to lawn and other areas may be filling them and they do not want the supplemental food as opposed to the natural vegetation. Additionally, they may taste the deworming medication and sense something is possibly wrong with their food. How many times do you medicate with the de-worming medication? Depending on your area, you may only need to provide it once or twice a year and not continuously if this is what you are presently doing. We would suggest that you take the food mix away from them for a couple of days. We have no idea what you are giving them, but would suggest you switch to poultry layer pellet/cracked corn and then supplement with a treat such as bread and lettuce to entice them to eat. They may be getting tired of the mix or it may not be sufficient or appropriate for their diet. Please let us know how this works out. They may just be tired of their food source and looking for something different. As long as they are eating, pooping and behaving normally, this should not be a problem. The Regal Swan