By Tina Mitchell, Greenwood Volunteer and Bird Enthusiast
As the seasons rotate between the northern and southern hemispheres, at any time somewhere on the planet, birds are singing. This time of year, the avian symphony around us provides glorious “ear candy” from sunrise to sunset. Bird songs are not just beautiful, entertaining, and up-lifting to the human ear. They also serve a vital function in one of the most basic avian drives among songbirds: during the process of reproduction, they use songs to establish and defend territories and to attract mates. As one branch of the order of Passerines (perching birds), these marvelous songsters are referred to as “oscines,” from the Latin for “a bird from whose note omens are taken.” Oscines have extraordinary brains that are hard-wired for learning and producing songs. Their double voice boxes—“syringes” in plural; “syrinx” in singular—are complex, with multiple pairs of tiny muscles controlling these dual membranes. Think of any lovely bird song you might hear in the spring—some of our native sparrows, any warbler, a finch—and you’re thinking of an oscine.
The other major sub-order of Passerines are the “suboscines”—rather arrogantly meaning “beneath the songbirds,” implying that they are more primitive. Suboscines have much simpler songs, less elaborate syringes, and brains that lack the intricate neural controls needed for complex songs. The most common suboscines in Colorado are the phoebes, kingbirds, pewees, and other species of flycatchers. Oscines generally need to hear and practice their songs while suboscines never need to hear even a peep from an adult to produce perfect songs. Pigeons and doves don’t need to hear adult song either. And although hummingbirds aren’t oscines, they also appear to require experience with adult songs when they are growing up. So to be able to sing appropriately as an adult, an American Robin (an oscine) needs to hear other robins singing. But a Western Kingbird? This suboscine’s adult song is genetically pre-programmed and requires no learning.
Beginning an hour or so before sunrise in spring and summer, the strongest and longest bouts of singing (referred to as “the dawn chorus”) occur. In fact, birding groups celebrate this lyrical phenomenon on International Dawn Chorus Day—this year, May 4 for the northern hemisphere. But what are these songsters trying to convey in the dawn chorus? Some are announcing that they made it through the night. (“Hey, neighbors. I’m still here. Don’t try anything.”) Some might be hoping to lure in a female who might have arrived overnight. (“Hey, baby—new here? Check out this great piece of land I’ve staked out.”) If you have American Robins in your neighborhood, they’ll probably be your first singers of the day (“cheeriLEE-cheerio cheeriLEE-cheerio”). (Remember the adage “The early bird catches the worm?” That early bird of yore was, indeed, a robin.) Other species chime in as the light increases. By mid-morning, the musical frenzy wanes considerably, although some species sing throughout the day. Another less intense round of singing kicks off as the sun begins to set. At our house, American Robins and Mourning Doves(“oo-AH-ooooo-oo-oo”) broadcast the last songs of the day.
You missed International Dawn Chorus Day, you say? No worries. The entire month of May offers you the opportunity to kick back, close your eyes, open your ears, and let the music pour into your soul. And it’s all free!