More than likely, these are juveniles (maybe even brothers and sisters)that were kicked out of the lake by mom and dad for the new nesting season. They will pal around and it is probably too early to determine if they are males or females. By the time that breeding season begins next years, two will have paired and there will indeed be an odd man/woman out. At this time, these pairings and play are normal as it teaches the young birds to prepare for mating. Sorry to hear about Carl. On the bright side, he may have found another pond with another mate!! The Regal Swan