Blackburnian warbler, Rondeau Provincial Park, August 5, 2023. Another fall migrant in the yard Setophaga fusca In springtime, rival male Blackburnian Warblers perform remarkable territorial conflicts that recall an aerial ballet. They chase one another through and around the treetops, flying in loops, plummeting downward through the branches in a whirling pattern, gliding with tail raised and spread, or slowly flapping in exaggerated “moth flight,” as researchers call it. Once territories are established, the aerobatics die down. source -Cornell Lab of Ornithology