The swans are too young to be given full reign of the habitat as they have no idea how to protect themselves. Their small size is a concern as owls and hawks could get them. The more time you have to train them to come inside at night, the more they will understand that this is part of their natural routine and their nightime home. This will also keep them safe and warm during the winter months. You need to have them reach approximately 7-8 months of age before allowing them to walk around as their size will be much larger and birds of Prey will no longer be a concern. Even, then larger predators such as coyotes bobcats etc., can be an issue, but keeping the swans indoors at night will help protect them from these predators. The Regal Swan