I start to scan the evening skies at the end of August each year for the first migrating Common Nighthawks (Chordeiles minor) patrolling for aerial insects over the fields and meadows of my local natural area--so far to no avail. Now that it's the last third of September, I'd all but given up hope of seeing them this year. I figured that I had either missed them, or that the population had gotten so small that they simply weren't to be seen, since the species is in severe decline (likely for lack of appropriate undisturbed nesting habitat).
Then, on a lark (so to speak), I decided to take a walk just before dark last evening. The sky was mostly cloudy, though the clouds weren't so thick that a gauzy crescent moon couldn't shine through in the southwestern sky. A neighbor of the natural area was finishing-up mowing his lawn in the growing gloom, and over his yard there appeared a Common Nighthawk, undoubtedly taking advantage of the insects sent skyward by the lawnmower. This sighting was about three weeks later than I usually see these birds.
A colleague of mine, playing Frisbee golf in an urban park last weekend, reported seeing five Common Nighthawks cruising over the park. Now I know they're just migrating a little later than I am used to seeing them, not that they've disappeared altogether.
During the remainder of my walk, I noticed that there were still plenty of fireflies to be found, mostly in the lower, damper portions of the natural area. A large amphitheater of a wet meadow near the natural area parking lot offers the very best firefly show in the area each year, but the fireflies have been absent from that meadow for weeks. I was surprised to see them so abundant in other parts of the preserve.
When I got to work this morning, a colleague asked if I'd gone for a walk in the natural area last evening. When I told him that I had, he said that he'd gone for a walk, too, and had been surprised by the fireflies, just as I had. He thought that the last time he recalled seeing a firefly was the end of August. A wondrous event.