Earliest recorded Tatarstan skylark in 2008: non-linear response to temperature suggests advances in arrival dates may accelerate

The return of the skylark Alauda arvensis is a traditional harbinger of spring in Central and Eastern Europe. The record analysed in this study of skylark arrivals in the eastern extremity of Europe is one of the longest extant records of bird migration in the world (131 yr between 1811 and 2008). In the last 30 yr there has been a rapid increase in March temperatures (ca. 3.7°C) and an advance in the arrival date of skylarks (11 d). 2008 was the earliest year in the whole record. The response of skylark migration to temperature is shown to be non-linear and it is anticipated that advances in arrival dates will now accelerate as temperatures continue to rise.