OK, to be fair it's singular. I took a quick snap at this bird and thought it had a bum foot. When I blew up the photo on my camera I realized that it actually has a mussel clinging to its toe. It must have been foraging in the saltmarsh, accidentally stuck his toe into the shell, and the mussel just clamped down. I'm actually surprised that the Wigeon was strong enough to pull it free since mussels tie themselves in pretty tightly.
And don't worry about the Wigeon. It was headed for the freshwater ponds at Cape May State Park. The mussel wasn't going to last too long immersed in fresh water.