Many summer evenings we sit on our deck in New Holland, Pennsylvania and watch the day come to a close. And during those evenings, we watch parades of puffy, gray, pink and white cumulus clouds pass across the sky while several kinds of wildlife are active, especially in August. The sun sets, a few stars become visible, and, at times, we see Venus and/or the moon. All that pageantry at dusk is entertaining, inspiring and free.
Just before sunset in August, a half-dozen chimney swifts, or more, sweep swiftly across the sky after flying insects, as they did during much of each day all summer. Meanwhile, little groups of post-breeding American robins wing over our neighborhood to roost overnight in nearby tall trees. But soon, those birds are on roost for the night.
Occasionally I see a few migrating nighthawks, which are entertaining swooping and diving after flying insects to consume as they pass overhead on swept-back wings on their way south ahead of winter. Some of them nested on flat, gravel roofs in cities, but are now going to tropical latitudes where flying insects will be available for them to eat through the northern winter.
Every year, during the latter half of August, several male annual cicadas broadcast pulsing, buzzing trills from tall trees in our neighborhood, as they do across much of the country. That shrill, often overwhelming, whining is produced by horny flaps on the males' lower abdomens and the pulsing occurs when each male moves his abdomen up and down while trilling. Cicadas also zip about among the trees to find partners to mate with. After laying eggs, both genders of cicadas die.
Cicada grubs live in the soil and suck sap from tree rootlets for about a year. But when mature, they crawl out of the ground, leaving quarter-inch holes in the soil, climb trees and other objects, split their brown, grub shells down the back and squeeze out of them, complete with two wings. When those wings are fully extended, the cicadas fly off in search of mates, leaving the empty shells hanging decoratively wherever they came to rest to emerge from them.
We see and hear other kinds of insects at dusk in August. A few, lingering male fireflies still flash their cold, abdominal lanterns, but their time will soon end completely. We see a few small, brown moths fluttering about outdoor lights. People in neighborhoods built in woods hear true katydids forever arguing about whether Katy did or didn't! We hear a few species of tree crickets trilling or chanting, depending on the species, in our shrubbery. We especially hear the rhythmic, seemingly endless, chirping of snowy tree crickets, also called temperature crickets because the higher the air temperature, the faster they chirp.
Other creatures are spotted at dusk in suburban neighborhoods. Garden spiders and other kinds of spiders weave webs at dusk for a night's snaring of flying insects. Some people hear the descending shivering of screech owls in taller trees. They might be young owls of the year that are establishing hunting territories and proclaiming their presences on them. Cottontail rabbits, striped skunks, opossums, and even white-tailed deer in some older suburbs emerge from hiding at dusk to seek food under the cover of darkness. Skunks waddling across a lawn is often an amusing, and fearful, sight.
But I think watching the aerial ballets of a few little brown bats in the air at once is the best entertainment outdoors at dusk. The bats hang in tall trees during summer days amid human activities and noise, emerge from hiding in quick succession soon after sunset and start out on the night's hunt for flying insects to ingest. Abruptly swooping and diving after victims in mid-air, they are swift on the wing, and highly maneuverable. And the bats are silhouetted beautifully against the darkening sky, creating exciting, unforgettable scenes.
Little brown bats live throughout much of North America. Females and their young of the year summer colonially in trees. Each adult is four and a quarter inches long with a wingspan of ten inches. They are furry and their wings are made of skin stretched from the fingers of the front legs to the toes of the back ones. Their tiny teeth grasp flying insects.
Hearing is the bats' best sense. Bats on the wing constantly squeak. The sound waves of those squeaks bounce off objects and return to the bats' ears. The bats form mental images of what is in front of them by hearing their vocalizations coming back to them, allowing them to avoid collisions and catch insects in mid-air.
Like all species of bats, little browns have one young per female per year. But bats can live 20 years in the wild and have few predators. Little brown bats are born in May to July and are left hanging by their mothers on their roosts while those mothers forage for food. But after a month, each youngster is able to forage for itself.
Once in a while, I visit a nearby, half-acre pond just before sunset to watch the entertaining succession of swallows, swifts and bats catching flying insects at every level over the water. Little clusters of mallard ducks float on the sunset-reflecting pond as the sun sinks into the northwest horizon while small flocks of American robins wing over the pond to their nightly roosts in nearby trees.
Several each of migrating tree swallows and local barn swallows, all dark silhouettes before the lovely sunset, careen swiftly among each other over the water after flying insects, with never a collision with their fellows. A few swifts sweep among the swallows in their quest for food.
And as the last swift is still catching flying insects, the first bat appears over the pond, beautifully silhouetted against the fading sunset. Then more bats appear until there are about a half dozen or more all sweeping over the water after insects. What a glorious, inspiring sight those swallows, swifts and bats on the wing make across the darkening sky!
August evenings are entertaining and inspiring. Get out at dusk and enjoy nature around your homes. Nature, wherever you live, helps make life more gratifying.
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