I'd say that ducks can fly, but then again, swimming in the ocean is basically just flying in water. I think I'd still go for the duck, though, assuming that it's the kind of duck I'm familiar with (Pacific black), since they're confident city dwellers so they have a lower chance of starvation or predation.

Would you rather have your soul encased in a phylactery (of your choice) that you have to carry around for the rest of your life knowing that some passing spirit might mess with it if you leave it somewhere, or spend one year as a wandering spirit unable to interact with the physical plane except by messing with people who use phylacteries?

Assume 0.1% of the population fills both niches.