Over the past week, I have noticed an increasing number of nighthawks on my walks to work, flapping and calling in the cool morning air. An obvious explanation is that the days are waning; two months after the summer solstice, I am now heading out into the faint light of dawn. Since nighthawks are crepuscular, hunting for flying insects at dawn and dusk, their morning routine has shifted with the diminishing period of sunlight.
Another reason is that these fair-weather birds are getting restless as their fall migration rapidly approaches. Now that the day length is comparable to that of late April, when they begin to arrive in North America, they likely sense that it's nearly time to leave. Indeed, large flocks of nighthawks will begin to circle southward in the coming weeks, ensuring that they escape to South America before the chilly nights of autumn kill off their prey.
As an observor who has lived at the same general latitude for my entire life, I have always been fond of nighthawks and have spent many hours watching their erratic flight across the evening sky. But I suspect that my attraction is rooted in the seasonal travels of these aerial acrobats, arriving as the warmth of May rescues us from a long, cold winter and departing as the cool evenings of late August and September bring a reprieve from the heat and humidity of a seemingly endless summer.
