Sounds of the Season

It is late summer, heading into fall, and now is the time of year that the afternoons and evenings grow noisier.  Some of the loudest species we hear throughout the year are currently active, calling to maintain contact with family members, to warn of impending threats, or to seek mates.  

Singing insects are out at all times of the day and night.  Crickets, katydids, grasshoppers, and cicadas four insect families active from late afternoon through the nighttime hours.  These species all produce calls using a process known as stridulation.  The edge at the base of a front wing, called a scraper, is rubbed across the base of the opposite wing, which has a bumpy surface called a file.  This movement can produce buzzing or chirping sounds as well as melodic tones.

Annual cicadas, Neotibicen spp., are a large insect averaging two inches in size with brown, green, or black bodies and white undersides.  Adult males find spots among the branches of trees and woody shrubs where they can hang out and call for a mate.  Calls can be heard throughout the day as a loud buzzing for several seconds that slowly fades to silence.  Cicadas get louder with warmer temperatures towards late afternoon but cease all calling as dusk settles.

Katydids, Pterophylla camellifolia, are well-camouflaged with long, green wings that look much like the leaves of the plants they hide in.  Despite their appearance, katydids along with crickets, from the family Gryllidae, and grasshoppers, from the family Acrididae, cannot fly.  Katydids choose to occupy branches in tall trees, while crickets and grasshoppers prefer lower vegetation, including tall ground cover, from which to call for a mate.  These insects will call well into the night on warm summer evenings, but quickly fade away once temperatures start to drop. 

Many of these calls are among the loudest made by wildlife.  A sound chamber, made by bowing out the wings from the body to create a hollow space, serves to amplify the sound.  From the high-pitched melodic notes of the katydid to the chirping of crickets and grasshoppers, these calls can resonate and carry long distances.

Against this background, we may also hear night birds, especially owls.  In northern Illinois, great horned owls, Bubo virginianus, produces a series of low-pitched hoots to warn off territorial invader, call to a young one, or attract a mate.  Eastern screech owl calls, Megascops asio, utter a long trill, lasting three to six seconds.  Owl’s calls are easy to recognize and can be heard over long distances, making them an effective method of communication in the dark.

Other sounds that you may hear at night include coyotes, Canis latrans, using yips and barks to maintain contact with other individuals, or by young when begging for food.  Long, drawn out howling is used to mark territorial boundaries and is often heard in response to emergency vehicle sirens, which we think are perceived as threats by coyote populations.  Raccoons, Procyon lotor, are another species that is very active during the late nighttime hours  approaching dawn.  If they are close by, you may hear purring or chittering sounds used between adults and their young.  Whether alone or in a group, when they are startled, raccoons will aggressively defend themselves and other family members emitting loud barking noises.  Screams and growls between fighting individuals are often heard.

Late summer evenings can be quiet and slow or full of noises and events.  Taking time to walk or sit quietly in your own backyards and listen can be a rewarding experience.  Come to the Jurica-Suchy Nature Museum or visit your local nature center to learn more about wild nights in your area.

^{Clockwise: Coyote, Canis latrans, by Paul Marvin, Apr 2012; Eastern screech owl-red morph, Megascops asio, by Laura M, Feb 2023; Great-horned owl, Bubo virginianus, by Don Miller, Jul 2016; Raccoon, Procyon lotor, by Alex ONeal, Aug 2010; Raccoon, Procyon lotor, by Ellya Selhub, Jan 2006}