Aggressive displays by male House Wrens are composed of multiple components that predict attack

Abstract

Aggressive signals should predict whether the sender of the signal will attack the receiver, yet this criterion has been little studied. We conducted experiments with male House Wrens (Troglodytes aedon) in north‐central Illinois in 2009 to test the hypothesis that rates of song delivery and wing‐quivering (putative aggressive signals) signal aggressive intent. We simulated a conspecific territorial intrusion by combining playback of male song with a male taxidermic mount, predicting that these signals would be related to a male's likelihood of attacking a conspecific. All males (N = 37) sang in response to the intrusion. Males attacking the mount sang at significantly higher rates and performed significantly more wing quivers than males that did not attack. In addition, all males that attacked the mount performed wing quivers (9/9), whereas only 53.6% (15/28) of males that did not attack did so (P = 0.011). Our results are consistent with the hypothesis that both song and wing quivering indicate a signaler's aggressive intent and that these signals are likely components of a multi‐component, hierarchical display.

Ready to Fight: Reliable Predictors of Attack in a Cooperatively Breeding, Non‐Passerine Bird

“…; Barnett et al. ). For example, low amplitude (soft) song reliably signals aggressive intent in several passerines (Ballentine et al.…”

“…Waas (1991a) identified a 'distancereducing' display that reliably predicted attack in little blue penguins, Eudyptula minor. The wing wave display is a reliable predictor of attack in male swamp sparrows, Melospiza georgiana (Ballentine et al 2008), song sparrows, Melospiza melodia (Templeton et al 2012;Akc ßay et al 2013), and house wrens, Troglodytes aedon (Barnett et al 2014).…”

“…Studies using the mount presentation protocol on birds have found evidence that certain songs, calls, and visual displays reliably predict attack (Searcy et al 2006;Xia et al 2013;Barnett et al 2014). For example, low amplitude (soft) song reliably signals aggressive intent in several passerines (Ballentine et al 2008;Laidre & Vehrencamp 2008;Searcy et al 2008;Hof & Hazlett 2010;Akc ßay et al 2011).…”

Territorial Responses of Nuthatches Sitta europaea—Evaluation of a Robot Model in a Simulated Territorial Intrusion

“…Response to STI has mainly been studied during the breeding season in temperate zones and northern latitudes, respectively [22][23][24]. Most birds in temperate zones defend territories during the breeding season to have exclusive access to food resources needed for raising offspring [25].…”

Song rate as a signal of male aggressiveness during territorial contests in the wood warbler

“…For example, song sparrows Melospiza melodia were shown to increase song rates in simulated territorial intrusions (Kramer et al , but see Searcy et al ), but rates of songs produced did not predict attacks (Searcy et al , Akçay et al ). In house wrens Troglodytes aedon , male song rate predicted subsequent attacks of the taxidermic mount, however, the other two criteria have not been addressed (Barnett et al ).…”