"He won't be washed down completely until tomorrow or the day after."
Mrs Jefferson said the shag had been set up in the crates used to help clean wildlife after the Rena oil spill.
She said the bird had an "overpowering" smell of oil and she had needed to open windows it was so strong.
"He hasn't ingested any oil and today he's standing upright rather than being spread out on the ground like the photo in today's paper."
It would take up to six weeks for the bird to regain waterproofing after it had been washed.
Any oiled wildlife should be reported to Department of Conservation's number 0800 362 468.