Even though the popcorn has no salt, it is not a natural food source for swans and therefore, should either be limited or not provided.

Cracked corn (mixed with poultry layer pellets) is the best food source for the swans as it provides the Vitamin A needed by the swans and is a more natural food. Also, the cracked corn serves as a filler which prevents the swans from feeling hungry. Popcorn is a very light food source and may not fill this need. The Regal Swan