So, the Daily Iowan had a piece today about how great Iowa City is for bird watching. But, did they mention the mysterious ducks? No. A ducky friend of mine also had no information but said that they had been drawing quite a crowd. Then I ran down our mailman who is a birder extrordinaire and he thought (based on description) that they were Muscoveys, a domesticated duck originally hailing from Central America. But as you can see from the pics, they are not so similar to the ones I saw down by the river. The mystery continues.
My theory: some domestic muscoveys got loose and mated with some local mallards.