In general, birds will increase their singing when they feel A. Safe, B. There is background music or sound of any kind so they aren’t drawing total attention to themselves. C. Other birds can be heard so there’s safety in numbers and someone to sing at.

A song can be a way of dealing with energy and emotion from something disturbing or exciting (called a “displacement behavior”) to sing out the excitement or annoyance. Sometimes, when the weather is changing I notice an uptick in the number of songs from my local sparrows.