• John A. Anderson/Shutterstock
  • A sparrow

For the Bleader’s Silence vs. Noise theme last week, I wrote about the minor phenomenon of late-night/early-morning bird chirping—a result of the same urban light pollution that helps guide home the drunks falling out of 4 AM bars the city wide. Of course, the nocturnal glow of street lamps isn’t the only distraction to a songbird’s mating and defense routines.

According to a recent study conducted in the Presidio district of San Francisco, sparrows have been forced over 35-some-odd years to raise their voices in order to compete with the city’s escalating clamor. Researchers David Luther of George Mason and Elizabeth Derryberry of Louisiana State studied the reaction songbirds had to calls recorded in the park in 1969 and in 2005. Guess what happened?