This is a little Northern Parula Warbler I saw on Hog Island in Maine. There was a pair always flying around where we stayed, they especially liked this flowering tree.
One day I had to rescue one that flew inside one of the buildings. It let me gently catch it and then sat in my hands until i brought it outside and let it go. It was really cool to hold a tiny little Warbler. It’s hard to get a sense of scale from these photos but it was small enough to fit in between my cupped hands.