Cathy Burgess has been recording the arrival and departure dates for red throated hummingbirds since 1986. The departure date for 2021 was observed to be September 18.
Here is a graph of her data. On a trend line basis the hummers are leaving a week later than they were 35 years ago. A bit more commentary can be found under the Climate Change Signals tab https://chandossier.com/climate-change-signals/