While the pen is quite at ease with her two day old cygnets, the cob appears as though he can't quite make out what they are, or where they came from. While he watches over them, he doesn't let them get too close. I've seen this behaviour in other cobs as well.
The two day old cygnets check everything out to see if it's edible.
The two day old cygnets watch closely as Mom shows them how to dabble for food.