If this is the case, says Fuller, the night-time singers could be sacrificing other activities such as feeding and preening in order to maximise their singing time.Somehow I have this vision of a cluster of German boy robins hoisting tiny beer steins in their wings as they belt out their tunes.
"There's a possibility these are unmated males that are really struggling. It could be in their best interest to sing as much as they can," he says.
. . .
Several studies have already shown that urban noise is causing city birds to change the characteristics of their song. A study in December 2006 showed that birds across Europe sing at a higher pitch to avoid being drowned out by the low-frequency din of traffic.
Other birds just sing louder. In Germany, some nightingales sing so loud they break European sound pollution regulations.
(This link and the following come courtesy of this week's Activate.)