This sounds like an introduction pen. When introducing new swans, they must be penned for approximately 1 1/2-2 weeks to get them accustomed to their new habitat, the other swans, the feeding system, etc. Otherwise, the birds will wander and possibly leave the area, get attacked by predators (domestic or wild) or get lost.

Now, having said this, the pen should be at least 12x24 feet, 1/2 in water and 1/2 on land with a zero entry so that the swans' feet and legs cannot get injured from climbing steep or abrasive areas. The swans must be able to swim, bathe, feed (water must be near food otherwise they can choke while eating), as well as have the ability to rest, dry out and preen on land.

The pen needs to be enclosed top to bottom so that no predator can access the birds and a feeder (whatever feeding system is to be used on the general pond) should be placed inside so the swans get used to the type of food, the caretaker as well as how the feeder works. The Regal Swan