Few sounds are more pleasant than the chorus of birds on a spring morning. Robins start in before the sun rises; their clear, bubbling songs echo across the darkened rooftops. Soon, song sparrows jump up on bushes to join them, and other voices from deeper hiding places. Raucous calls of jays and crows punctuate the melodies. Woodpeckers, lacking strong vocal talents, pound out rhythms on lampposts and house sidings. Whether in Cairo or Copenhagen, a similar chorus formed of local accents rises with the warming sun. Peaceful, isn’t it?

Not really. What we actually hear when stepping into the fragrant air is aggressive or lascivious shouting. As behavioral biologists Sanne Moorman and Johan J. Bolhuis have written: “The main function of song seems to be defense of territory and mate...