Most swans will chase geese. However, because your male's mate was killed, he may not have the need to defend his territory at this time. He should have an increased testosterone level during the mating season, and it may just take him a little longer to get this hormone increase in the next few weeks. Once this occurs, just by the nature of the hormones, he should start chasing the geese. If this behavior does not appear, then you may need to try using a feeder or another type of food that does not float. Try using a mixture of cracked corn and poultry layer pellet which he can access below the water with his long neck.

If this still does not help the situation, you may need to build him a pen (1/2 on water 1/2 on land with feeder inside (enclosed top to bottom so that no predator can dig under or crawl into the pen). Keep him in the pen in the area that you want to feed him so that once you release him from this area, he will first, have gotten used to the geese and vice versa, and second, will cause him to stay in that area and not stray. If you do not have a pen, you might want to bring him indoors (shed, garage, etc., safe from predators) for a couple of days. Feed him and let him get his wits back as he may still be skittish from his mate being killed and the foxes in the area. Keeping him inside (1 hour after dawn and 1 hour before dusk) may be a good idea to protect him from the foxes. Alternate his release onto the pond and capture to the indoor pen at night by 1/2 hour or 15 minutes so that the predators do not time his release or capture.

Being chased by a goose is not helping the situation as he could walk into an unsafe area and be predated by a fox or other wild predator as well as a domestic predator, (i.e., human, dog or cat) or hit by a vehicle. He could also just roam away from your pond and you might not be able to find him. The Regal Swan