Wilson's warbler, rondeau Provincial Park, Ontario, Canada,May 2018.
Took a long time to find this bird. Fortunately he came out foris photo shoot.
Naturalist Alexander Wilson, often called the "father of American ornithology," described the Wilson’s Warbler in 1811 which he called the “green black-capt flycatcher.”
source - https://www.allaboutbirds.org/guide/Wilsons_Warbler