A Ruddy Shelduck was seen on the salt water mud flats of Ninigret Pond in Charlestown, RI on the evening of 8-Aug-2006. It loosely associated with a flock of gulls that was roosting in the center of the flats. When approached, the bird kept its distance and walked away along with the flock of gulls. The photos show that the bird did not have any bands or tags. As far as I know, this bird was not relocated after 8-Aug-2006. The bird is apparently a female since it has significant white area around the eye.
According to "Rare Birds of North America" by Steve N.G. Howell et. al.:
Ruddy Shelduck is popular in captivity and N. American records are routinely dismissed as escapes, which is almost certainly the case - most of the time. Tracing records of Ruddy Shelduck in N. America would be a time-consuming task, but we consider that natural vagrancy is plausible and suggest that observers make an effort to document records of Ruddy Shelduck so that any patterns may be elucidated.