Thank you for the reply and advice. On further observation of the neighboring swans, it occurred to me that they might well be juvenile mute swans . (A former property owner had a pair of breeding mute swans years ago, and we watched some of the cygnets develop). I'm sorry the photos were so poor but I'll try to take more if possible. Whatever their specie or gender, I'm certain they are juveniles and well-contained on their own property.

As for Swany, I'm reluctant to remove her eggs for the reason you cited. Is there any "safer" time when I could remove the eggs - e.g., in a week or two - when she would be less likely to double clutch? (Last egg was laid on 7/4) As concerned as I am for Swany's well-being, I don't know how I could survive the responsibilities of protecting cygnets should the eggs turn out to be fertile. And, if the cygnets actually survived long enough, I would have to find good homes for them, which would be complicated and stressful. In short, I'm afraid this would become an impossibly overwhelming situation. For now, I'm leaving the eggs to Swany's care and making sure she has extra food & water available. She leaves the nest for brief swims in the pond but most of her time is spent on the nest. Thank you again and for all your comments and suggestions, and I will keep in touch.