Yes, they need access to land. From the photos, you will need to wait at least 4-5 months before you put them in a pond by themselves. These cygnets will not survive on their own at this size. Egrets, turtles, owls, hawks, herons, raccoons, foxes, coyotes, bobcats, anything can get them at this age.

You need to get a larger kiddie pool and sink it into the ground forming a zero entrance so they do not injure their legs or feet. You can build a fenced in pen around them with a feeder inside. The pen needs to be completely enclosed so that predators cannot dig under or climb over and into the pen. From the bottom of the pen, up to four feet on the perimeter of the pen should be poultry fencing so raccoons cannot reach in and grab the cygnets and the cygnets cannot try to crawl out of the pen and get strangled in the fencing. Provide 4 feet of grass around the kiddie pool in circumference so the cygnets can enter and exit the pool to dry and preen. Additionally, you will need to have a means to drain and add water on a daily basis to keep the pen clean.

Otherwise, you can build a large pen in the pond (same pond that houses the parents)using the above directions, 1/2 on land and 1/2 in water. Still, coat the perimeter of the fence with the poultry fencing so the cygnets cannot crawl out of the pen. See if the adult swans might accept them after a few weeks, probably not, but we have seen stranger things. In any case, the pen in the pond with the parents allow the cygnets to understand that they are swans and you won't have to clean the pens if the water is from the pond.

You will still be able to observe the cygnets, keep their food clean and in adequate amounts, but they will have more interaction with the older swans than you. If the parents do not accept them, you can still raise them in this pen for 4-5 months until they are much larger. Then, you will need to build a similar or move the pen to the other pond. The cygnets will need to stay on the pen at the other pond for approximately 2 weeks allowing them a proper introduction to their new habitat so they do not wander looking for you and the other swans. The Regal Swan