The full search was: “it is september why am i only getting female hummingbirds at my feeders and she is very aggressive”
By September, most of the migratory hummingbirds remaining at northern latitudes will be young birds of both sexes, which look like adult females except for variable amounts of pale fringing on the iridescent feathers of their backs and heads (plus a few other subtle differences, depending on species). Young males often show lines of dark spots on the throat, a pattern hummingbirders call “five-o’clock shadow.” Some young males will show bright flashes of color in their gorgets as adult feathers replace drab juvenile ones.
Though females of any age can be very aggressive and territorial, especially in migration, it’s the young males that seem to be the biggest troublemakers (as though they think they have something to prove). As long as there are still good numbers of hummingbirds around, expect the screeching, chasing, grappling, and chest-bumping to continue.