Variation in Trill Characteristics in Tree Pipit Songs: Different Trills for Different Use?

Abstract

Transmitting information about singer's quality is an important function of song in many bird species, and this information should be useful in territorial interactions. Fast trills, being physically demanding song structures, are particularly suitable candidates for signalling of quality or aggressive motivation. We have evaluated trill characteristics in songs within a population of the Tree Pipit, a common European songbird with no sexual dimorphism, in which song apparently plays a key role in territory defence as well as mate choice. Two types of relatively fast trills (each of them in multiple variants differing in complexity) were commonly observed in repertoires of Tree Pipit males. Trill rates significantly differed among individuals, suggesting that these song structures may carry information about male quality in this species. We tested by playback experiments whether both trill types are used in territorial encounters. Only one of the trill types was sung by males in response to playback, regardless on the trill type played to them. In an immediate response to playback, they increased the frequency of use of this trill, and also significantly increased the trill rate in comparison with spontaneous songs. This confirmed field observations, suggesting that this trill is important in male-male interactions. On the contrary, the use of the fastest, apparently more demanding, trill type actually decreased after the simulated territorial intrusion. We hypothesize that the latter one is more directed towards females, and that while performance of both trill types may reflect male quality, they are primarily used in different contexts.Ethology 120 (2014) 586-597

Repertoire‐based individual acoustic monitoring of a migratory passerine bird with complex song as an efficient tool for tracking territorial dynamics and annual return rates

“…These dynamic changes may have resulted from lower success of some males in intrasexual interactions (Petrusková et al . ).…”

“…5 min for a typical spontaneous singing male; Petrusková et al . ) was substantially lower than time required to unambiguously detect ring combination or its absence (often tens of minutes to an hour of an intensive effort with binoculars), and recordings could be obtained by relatively inexperienced team members. The time required to process the recordings varied according to previous experience and recording quality.…”

“…S1, Supporting information; for more details, see Petrusková et al . ). Most Tree Pipit males arrive there in late April and early May, but latecomers may occur even in late June.…”

“…Upon each visit, we attempted to record each encountered singing male for at least 5 min (this should yield about 30 songs considering an average song rate of six songs per minute; Petrusková et al . ) using Marantz PMD 660 and 661 digital recorders equipped with Sennheiser ME 67 shotgun microphones. Singing posts and song flights of recorded males were noted, from which an approximate position of their territories could be estimated (as in Kumstátová et al .…”

The intensity of male-male interactions declines in highland songbird populations

“…S2). We used the song of individuals recorded in the study area as a stimulus to simulate territorial intrusion, a technique that has been successfully used with pipits to study territorial and sexual behaviours (Petruskova et al 2014) and to lure birds for capture-mark purposes (Melendez et al 2014). We performed playback tests at four sites, separated by 3.5 -20 km: two sites were at the lower limits of the species' distribution (one at 1091 -1193 m and the other at 1050 -1225 m) and two sites at the upper limits (one at 1853 -2152 m and the other at 1763 -2193 m) (Fig S1,Table S1).…”