Effects of temperature and season on birds’ dawn singing behavior in a forest of eastern China

Abstract

Birds’ dawn chorus is a daily period of high song output, which mainly occurs during the breeding season. Monitoring such chorus may provide important information about birds’ ecology and the function of bird vocalizations at dawn. In this study, we have recorded dawn singing activity from April to June 2019 at seven different sites in Yaoluoping National Nature Reserve (YNNR) in the eastern China and examined the effects of extrinsic factors such as temperature and time of the season on the dawn singing behavior of four common birds Alstrom’s Warbler (Phylloscopus soror), Streak-breasted Scimitar Babbler (Pomatorhinus ruficolli), Brownish-flanked Bush Warbler (Cettia fortipes) and Chinese Hwamei (Garrulax canorus). In total, we analyzed 1511 days of recordings, 417 days for Alstrom’s Warbler, 343 days for Streak-breasted Scimitar Babbler, 391 days for Brownish-flanked Bush Warbler, and 360 days for Chinese Hwamei. Our results showed that the dawn singing start time of Alstrom’s Warbler, Streak-breasted Scimitar Babbler and Brownish-flanked Bush Warbler were negatively affected by temperature in such a way that birds started singing later at the higher temperature; however, dawn singing start time of Chinese Hwamei was not affected by temperature change. As for Alstrom’s Warbler and Brownish-flanked Bush Warbler, their singing rate decreased significantly with high temperatures, whereas the singing rates of the other two species were not significantly related to the temperature. The Julian date did not affect the dawn singing start time of any species. The Julian date influenced the singing rate of Alstrom’s Warbler, Brownish-flanked Bush Warbler, and Chinese Hwamei. In contrast, the singing rate of Streak-breasted Scimitar Babbler remained constant with the seasonal progression. Our results indicated that bird’s dawn singing activity is species-specific and is sensitive to environmental factors such as temperature and time of the season.