The signs of fall are starting to show. Just this week, I saw upward of 50 common nighthawks in one sighting during the evening hours. These are typically a solitary bird and about the only time they are seen is in the evenings when they feed. As I understand it, they will form loose flocks for foraging and migration and this is the time of year that starts. They will swoop about just above the treeline along open fields as they feed on flying insects. There is a very distinct white patch on each wing. Despite the name “nighthawk”, they are grouped in a small category of birds called “Goatsuckers”, which is a name that originated in medieval times from a wrongly-held belief that they suckled on goats a night.
Need more info?: https://www.allaboutbirds.org/guide/Common_Nighthawk/id