The turtles could be present for both reasons. The high/dry nest out of the water provides the turtles with a nice sunning shot within range of moving back into the water quickly in the event a predator approaches (i.e., humans, dogs, etc.).

Additionally, turtles can eat eggs, but usually feed on small birds such as ducklings, goslings or cygnets. So, having the turtles next to the nest is not the most concerting news. However, this is part of nature and the mother swan will protect the young cygnets as much as possible.

We had a turtle (soft-shell) actually bite one of the swans at a facility where we act as consultants. The cygnet's webbed feet were nearly stripped of the webbing. Dr. Geoffrey Gardner, one of The Regal Swan's veterinarians, cleaned and sutured the bird. The swan has lived a full prosperous life and is 11 years of age this year. So, natural predation is normal and most likely, once the cygnets hatch, the parents will chase the turtles from the nesting area. The Regal Swan