Spring is near and birdsong fills the morning air
Winter is fading, spring is coming, and birds are singing.
The distinctive songs of eastern meadowlarks roll across prairies surrounding our metropolis. The males perch on fence lines, fence poles and utility lines with puffed-up yellow breasts while singing flutelike tunes.
To our ears, the meadowlark’s song is a jubilant melody with the words “spring-of-the-year.”
Neighborhood birds have also begun singing pretty melodies. Right now, they’re calibrating their songs like violinists in an orchestra readying violin strings for a stirring concert.
American robins sing multituned “chirrupchirrup” tunes in preparation for their mellifluous dawn song during spring that sounds like the words “cheerily-cheerilywake-up, wake-up.”
A male eastern bluebird perched atop his yearly nest box in my yard softly sings “chuwee-chuwee” tunes. In March, he’ll croon with a lilting warbling song sounding like “turee-turee-chuleee” as the female dutifully begins nest building.
Since New Year’s Day, pine warblers have been perfecting their spring song of high-pitched trilling notes that reach the upper limits of human hearing. Luckily for us, they’ve been singing low in the trees between feeding sessions at bird feeders.
When they return to the upper canopy of pine trees in spring, none but the keenest of human ears will hear their tunes.
No problem hearing the piercing song of a northern cardinal. The male is beginning to belt out his sonorous tune sounding like “cheer, cheer, cheer, pretty-pretty-pretty” as though heralding the blossoming of redbud trees.
Birds don’t sing to entertain us, despite our joy in listening to them. They instead sing to conduct the business of producing a new generation.
Male birds first sing to declare territorial ownership. A male’s song says to other birds of his kind, “This space is my breeding territory, not yours.”
A male also sings to announce his availability to females. But he must compete with other singing males. For example, a male eastern meadowlark will pair up with two females, and his song must outdo the songs of other males for female attention.
For monogamous birds like northern cardinals, the male sings to assure his mate he’s staked out breeding grounds with food for her chicks. Yet a male cardinal during his first year of breeding faces
• A bird sings from a bony vocal chassis called a syrinx resting in the chest at the base of the windpipe.
• Twin bronchial tubes branch from the windpipe into the lungs.
• Muscular action in the syrinx stretches and relaxes thin syringeal membranes.
• Song occurs as air from the bronchi vibrates the membranes while muscles adjust membrane tension, somewhat like a human drummer adjusting the skin on a drum.
• The more complex a bird’s syringeal muscles, the more complex the song.
• Bird songs resonate within the syrinx, which allows birds to sing with beaks closed — human songs resonate within the oral cavity, which requires opened mouths.
competition for breeding grounds and for a female against other first-year males.
The female usually selects a male with the most vigorous song because he will have healthy genes for her chicks.
Gary Clark is the author of “Book of Texas Birds,” with photography by Kathy Adams Clark (Texas A&M University Press). Texasbirder@comcast.net