Effect of climatic factors on the singing of forest birds

Abstract

To clarify effects of climate change on birds, we recorded the dates when forest birds began actively singing and analyzed the relationships with temperature and precipitation. Observations were conducted at four forest sites from 2009 to 2021. The mean temperature in May was identified as a factor that influenced the timing of active singing for all five species (Asian Stubtail Urosphena squameiceps, Eastern Crowned-warbler Phylloscopus coronatus, Siberian Blue Robin Larvivora cyane, Narcissus Flycatcher Ficedula narcissina, Grey Bunting Emberiza variabilis). The mean temperature in April was significantly correlated only in Narcissus Flycatcher. The temperature during the most recent period to the start of singing may have had a strong influence on singing behavior. In the case of the Asian Stubtail, precipitation in April had the strongest effect on the date when the species became active. The Asian Stubtail typically forages and nests in the bushes near the ground, so April precipitation, which melts snow cover, possibly has a strong influence on stubtail behavior. Species like Grey Bunting and the Siberian Blue Robin also forage close to the ground, so monitoring the snow cover by interval cameras may be an important additional method of study.