Influence of Astronomical (Lunar)/Meteorological Factors on the Onset of Dawn Song Chorus in the Pied Bush Chat ( Saxicola caprata )

Climatic factors which prevail during the breeding season of avian species in spring and early summer may trigger the onset of singing behaviour in songbirds. To understand the effect of climatic variables on the onset of dawn song chorus, we conducted a study in the natural habitats of a tropical songbird, the Pied Bush Chat Saxicola caprata in Haridwar, Himalayan foothills, India during early spring. The results indicated that the onset time of dawn chorus depends on a number of environmental factors. The song bout length depended on daily temperature, rainfall rate, wind direction, photoperiod, lunar phase, indices of apparent temperature, dew point, sunrise timing and day length, whereas the song rate depended on daily temperature, photoperiod, indices of apparent temperatures, dew point, sunrise timing and day length. Further, stepwise multiple regression revealed that onset time of dawn chorus was dependent on photoperiod and lunar phase, while song bout length and song rate were influenced by day length and sunrise timing respectively.