By Christine Morris
Rolling into my driveway the other night I heard a strident peeping. My new pullet must have flown the coop! I began to search under an unused truck topper when I heard the peep again from an impossible height for a chicken. Looking up I saw, of course, an Evening Grosbeak.
Evening Grosbeak call:
Recording by Lance A. M. Benner, accessed on Xeno-canto.org: XC292471
Though a year-round resident of Western Montana, Missoula sightings this spring are more numerous than usual. They pose for fourth grade students at Maclay Flat and Master Naturalists at Council Grove. They loudly peep in the neighborhood elms and chirp softly in Douglas-firs.
The Evening Grosbeak is a songbird that doesn’t sing. It sounds like a chicken. Specifically like a pullet or chick (roosters can sing, though we don’t often think of their crowing in musical terms). Male and female Evening Grosbeaks do make calls—loud and fairly high-pitched notes as well short blurry chirps. Most other male songbirds have a repertoire that contains both songs and calls, often including variations of each. The Black-capped Chickadee, for example, can make 15 different sounds, of both songs and calls.
Melodious bird songs are created by the syrinx, which receives air from both bronchial tubes. Each side of the syrinx is controlled independently, allowing for the production of two pitches simultaneously. Songbirds tend to have a greater number of muscles controlling the syrinx than other birds. The human equivalent is the larynx, which is situated higher, receiving air from only one source and therefore incapable of a bird’s musical dexterity. Some humans can overcome this deficit by manipulating their tongue to create a resonant chamber in the mouth producing two pitches at the same time. For example, this Tuvan throat singer:
Birds sing for a variety of reasons including courtship, indication of sex, and territoriality. Even short, simple songs may contain more information than a human can appreciate. According to psychologists Robert J. Dooling and Nora H. Prior, “there is an acoustic richness in bird vocalizations that is available to birds but likely out of reach for human listeners.” This claim is based on their study with zebra finches. The trained finches were able to identify small variations in song and song syllables that human listeners could not perceive. This auditory acuity can be explained by recent findings published in Animal Behavior that smaller species with faster metabolisms perceive time at finer resolutions, i.e., what they hear and see is slowed down compared to what we perceive. Hear bird songs slowed down:
The calls and chirps of Evening Grosbeaks may have richer meaning than we can hear or understand. Trying to untangle the reasons why they don’t sing, however, may be an impossible journey into evolutionary history. Perhaps their behavior can provide some clues.
Evening Grosbeaks are social birds, traveling to food sources in large flocks. Local birders Paul Hendricks and Larry Weeks noted that decades ago flocks 500 strong would show up in Missoula to feed on Chinese elms. The birds tend not to display aggression toward each other at winter feeding sites and do not display territoriality during breeding. Rather than song, courtship involves a dance. The male vibrates his wings while turning back and forth displaying vibrant feathers in yellow, black, and white. Other courtship behaviors include vigorous bowing by both sexes and food items ceremoniously offered to the female.
Without reason to defend territory and using other sources of enticement for pairing these birds may find shorter call notes sufficient and energetically appropriate. As MNHC’s Jenélle Dowling says, “it’s all about the tradeoffs.” What sounds like a chicken to us is just part of a larger life history.
Want to learn more? Check out these resources:
The Alluring Language of Crows and Ravens by Dr. John Marzluff:
The Nine Most Important Things to Know about Bird Song:
What Do Birds Hear When They Sing Beautiful Songs?
Small Animals Live in a Slow-Motion World by Emilie Reas:
On Evening Grosbeaks in particular: