Dawn song of male blue tits as a predictor of competitiveness in midmorning singing interactions

Abstract

During the dawn chorus, territorial male songbirds vocalise intensively within signalling range of several conspecific males and can therefore be considered members of a busy communication network. The more or less continuous singing over a long period of time under standardised stimulus conditions makes the dawn song a potentially important information source both for simple receivers and for eavesdroppers. Male blue tits (Parus caeruleus) vary in features of their dawn song, e.g. older males sing longer strophes, and females choose males that sing longer strophes as extra-pair partners. However, so far, dawn song in the blue tit has been investigated separately from other singing behaviour of the same males. In this study, we investigate aspects of blue tit male quality, reflected in dawn song characteristics, and their predictive value for how males behave during singing interactions later in the morning. We acted as simple receivers by recording the singing activity of one male at a time at dawn and compared features of its dawn song, such as onset before sunrise, repertoire size, mean bout length, strophe length and percentage performance time to responses of the same male to a territory intrusion simulated by playback of synthesised songs later during the same morning. We assume that an aggressive response towards an intruder will involve a fast approach to the loudspeaker broadcasting strophes of blue tit song, searching for the intruder (flying around), and a high amount of counter singing and overlapping of the intruder's songs. Aspects of vigour of response to the simulated intrusion could be predicted from all five investigated dawn song parameters as well as male age. This is, to our knowledge, the first indication that a simple receiver could extract reliable information from a male's dawn singing behaviour about its competitiveness later in the day.

Black-Capped Chickadee Dawn Chorus and Subsequent Sexual Activity

“…Rather, during the chorus song output of males may honestly signal individual condition-males display their quality to listening receivers by outsignaling rivals (Otter and Ratcliffe 2005). In support of this hypothesis, studies have found that song output at dawn often closely approximates attributes of males' energetic state or access to resources (Lucas et al 1999, Welling et al 1997, Poesel et al 2004, Murphy et al 2008). In such a scenario, females are able to assess individual differences in males' quality by assessing of song output from a large number of males simultaneously (Otter and Ratcliffe 2005), thus facilitating comparison of her mate against potential extrapair sires.…”

Dawn singing behavior of a tropical bird species, the Pied Bush Chat Saxicola caprata

“…It has been reported that during the dawn chorus, territorial male song birds sing intensively within signaling range of several conspecific males and can therefore be considered members of a busy communication network. The more or less continuous singing over a long period of time under standardized stimulus conditions makes the dawn song a potentially important information source both for simple receivers and eavesdroppers (Poesel et al, 2004). Moreover, dawn appears to be the best time for singing because the hindrances to acoustic communication are least at this time of the day (Brown and Handford, 2003).…”

“…Studies also suggest that the receivers that focus solely on physical song characteristics of a male may gain information about the male's willingness to escalate a fight (Dabelsteen and Pedersen, 1992); its previous experience or age (Lambrechts and Dhondt, 1986;Welling et al, 1995); current body condition (Godfrey and Bryant, 2000) and social rank in a network of territorial individuals (Otter et al, 1997). Besides this, song characteristics of male may also help female assessing male's quality (Kempenaers et al, 1997;Poesel et al, 2004). For example, song characteristics might reveal that good quality males are better at parental care (Forslund and Part, 1995), possess better territories (Catchpole, 1986), are less infected with parasites and/or are more immune against pathogens (Saino et al, 2003;Garamszegi et al, 2005).…”

A distinct reed bunting dawn song and its relation to extrapair paternity

“…Females may thus be able to estimate the quality of these males throughout the breeding season. Females can more easily compare the songs of different males early in the morning because all males then sing simultaneously (Mennill et al 2002;Poesel et al 2004). In addition, songs are loud and clear at dawn because of the temperature inversion that forms a tunnel of cold air, there is little or no wind, and little environmental noise (Slabbekoorn 2004).…”