I assume the Prairie Warbler I saw several times this week is the same one reported near the Legion in St. John's more than two weeks ago. If so, it is staying around a long time, perhaps enjoying the warm weather and ample food supply.
Not all glimpses of this bird were at the same time, nor at the same angle. On one occasion this was the look I got. The sighting was brief and distant. Taking away three sad photos, it looked like the undertail coverts were yellow. For a while I thought I had a different bird. With help, the ID is confirmed: Prairie Warbler in weird light only making the coverts look yellow.
At another time, I got this quick look. This bird flew in front of me and landed on a nearby branch. It looked extremely green. Again, snapping what I could, I got this shot. Clearly the coverts are white like the Prairie, but I could not see the wing bars. Again, I thought it might be a different bird. Three different views; three different shots all added up to be the same bird. Imagine I only had my mind's eye to review. I'm sure I would easily have thought I saw three different birds. Oh, so much to learn.