DAWN SINGING OF EASTERN PHOEBES VARIES WITH BREEDING STAGE AND BROOD NUMBER

摘要

The dawn chorus is a daily period of continuous singing by male songbirds that begins prior to sunrise. It is relatively less studied than daytime singing, and particularly in suboscine birds. We analyzed dawn singing of 14 Eastern Phoebes (Sayornis phoebe) in Echo Bay, Ontario over the 2011-2012 breeding seasons. We measured time of first song, length of dawn bout, time of final song, average song rate, and peak song rate and compared these characteristics among breeding stages. Results indicated that breeding stage was a significant predictor of all five dawn song features. Our results suggest that dawn singing of Eastern Phoebes is directly related to female fertility. We show that males begin singing significantly earlier when females are fertile. Males sang significantly longer during fertile and incubation stages than while feeding young. Males began singing later and sang for the shortest duration during the pre-breeding period. Song rates were higher in first broods than in second broods. We showed that suboscine dawn signaling patterns vary across breeding seasons in ways similar to oscine songbirds.