02429nas a2200253   4500008004100000245012300041210006900164260001600233300001400249490000800263520160100271653002601872653002501898653003401923653002201957653001501979100002001994700002702014700002302041700001702064700002402081700001502105856005502120       2018                        eng d00aQuiet violence: Savannah Sparrows respond to playback-simulated rivals using low-amplitude songs as aggressive signals0 aQuiet violence Savannah Sparrows respond to playbacksimulated ri  cJan-10-2018  a724 - 7320 v1243 a<p>When animals compete over resources such as breeding territories, they often use signals to communicate their aggressive intentions. By studying which signals are associated with aggressive interactions, we gain a deeper appreciation of animal behaviour. We studied aggressive signalling in male Savannah Sparrows, Passerculus sandwichensis, focusing on signals that precede physical attack against territorial intruders. We simulated intruders using song playback and taxidermic models, and we determined which behaviours were associated with physical attack. Previous studies that have used this approach suggest that many species produce songs of dramatically lower amplitude, or &ldquo;soft songs,&rdquo; as signals of aggressive intention. Savannah Sparrows, however, are not known to produce soft songs, and therefore, they provided an interesting system for testing signals that predict attack. Of 93 playback subjects, 23 males attacked the simulated intruder and 70 did not. To our surprise, Savannah Sparrows produced soft songs, and the number of soft songs was a significant predictor of attack on the simulated intruder. Birds also showed a nonsignificant tendency to produce more &ldquo;chip&rdquo; calls prior to attack on the simulated intruder, whereas three other measured behaviours (aggressive calls, wing waving and passes over the model) did not predict attack. Our study contributes to the growing body of research on aggressive territorial signals and reveals that soft song is an even more widespread signal of aggression in songbirds than previously recognized.</p>
10aaggressive signalling10aanimal communication10alow‐amplitude vocalizations10aSavannah Sparrows10asoft songs1 aMoran, Ines, G.1 aDoucet, Stéphanie, M.1 aNewman, Amy, E. M.1 aNorris, Ryan1 aMennill, Daniel, J.1 aKoenig, W.  uhttp://doi.wiley.com/10.1111/eth.2018.124.issue-1002451nas a2200169   4500008004100000245011300041210006900154260001600223300001400239490000800253520189100261100002502152700002402177700002202201700001502223856004302238       2017                        eng d00aSexual differentiation and seasonal variation in response to conspecific and heterospecific acoustic signals0 aSexual differentiation and seasonal variation in response to con  cJan-06-2017  a460 - 4660 v1233 a<p>Interspecific territoriality is frequently reported between closely related species; however, few studies have demonstrated interspecific territoriality between distantly related species living in sympatry. We conducted playback experiments to investigate territorial behaviour in male and female White-bellied Wrens (Uropsila leucogastra) in response to simulated conspecific and heterospecific intruders during the breeding and non-breeding seasons. We explored whether heterospecific songs of the Happy Wren (Pheugopedius felix), a distantly related species and ecological competitor, elicited antagonistic responses from focal White-bellied Wrens, and whether such responses differed between the sexes. We also examined whether male and female responses to conspecific and heterospecific rivals varied with season. We found that male White-bellied Wrens always responded to conspecific song, and responded significantly more to heterospecific song compared to a control stimulus (Tropical Parula, Setophaga pitiayumi). In contrast, although female White-bellied Wrens responded strongly to conspecific song, their response to heterospecific song did not differ significantly from the control stimulus. The proportion of males that responded to heterospecific songs and the proportion of females that responded to conspecific songs varied seasonally, showing significantly lower responses during the breeding season. The intense responses of male White-bellied Wrens to playback of heterospecific songs suggest that they recognise ecological competitors based on their vocal signals. Furthermore, the decrease in agonistic interactions during the breeding season is in line with the hypothesis that aggressive behaviour may be detrimental to reproductive and parental activity, and the hypothesis that heterospecific animals pose less of a threat during the breeding season.</p>
1 aSosa-López, Roberto1 aMennill, Daniel, J.1 aRenton, Katherine1 aKoenig, W.  uhttp://doi.wiley.com/10.1111/eth.12616