Songs allow birds to mark out a territory, which protects the resources they need to breed. The song is a challenge to other birds of the same species, but also prevents conflict because birds who do not wish to challenge for the territory can avoid it. Peak activity for birdsong in our climate is crepuscular – in the time around and after dawn and again in the evening. The dawn (and dusk) chorus, where birds of many species sing, is one of the glories of nature and one of the most powerful signs of spring.
It is rather difficult to pinpoint when birdsong begins again. Robins, for example, sing a little all through winter. It is a sound of hope in the darkness and also reflects that Robins maintain a territory through the winter. Some species will begin to sing in mild weather, but stop again if the weather worsens.
This year, the first day I heard a substantial amount of bird song was on 27 January. I noted that not only did I hear a Robin, but that there was a great tit (whose song is very monotonous) and several blackbirds singing in the dusk. In 2014, I experienced something similar on 8th January – weeks earlier. It was much milder in 2014, of course.
Last week, here and at College on the South Downs, there were a couple of days with lots of birdsong, which I am hearing much better now I have hearing aids to help with high frequencies. There were lots of thrushes singing at College – quite wonderful.