If the swans have an orange bill, they are Mute Swans. This is the swan species that Michigan DNR along with other federal and state wildlife officials are killing so the larger Trumpeter Swans can be hunted as a Trophy Waterfowl.

Trumpeter Swans are much larger and have dark black bills.

The swans should leave, but the best way to expedite their migration is to immediately stop the feeding. If the swans fail to migrate, you will need to ensure that the pond does not freeze (use of an aerator/de-icer), or at least break up an area so that the swans can stay near the shore without getting caught in the deep ice and drowning. Conversely, the area needs to be at least 20 feet in circumference and at least 15 feet from the shore. This will allow the swans to escape into the water should a predator crawl onto the ice to attack the swans. You will need to provide supplemental feed so the swans do not starve in the winter. You will need to provide them a mixture of cracked corn and poultry layer pellets in the water. Do not feed near the shore or on ice as thiis can attract predators. You will also need to provide them with lettuce and you will need to dump food several times during the day.

The best scenario is to get the swans to leave.

There are no guarantees that the swans will return to your pond in the winter, but they most likely will if they find the habitat suitable for nesting. Feeding will be remembered, so that may entice them to return. However, if the swans are Mute Swans, their chances of survival during the migration will be greatly diminished with the Michigan DNR's efforts to kill them. The Regal Swan