The function of seasonal song in a tropical resident species, the Red-throated Ant-tanager (Habia fuscicauda)

Abstract

Recent studies of tropical birds with year-round territoriality indicate that song rate is relatively low yearround in association with lower seasonality and relatively stable social environment over the year. We examined seasonal variation in the song rate of Red-throated Anttanagers (Habia fuscicauda), a socially monogamous species in which males predominantly sing during the breeding season, to determine to what extent increased song rate is driven by (1) increased territory defense, (2) pair coordination of nest initiation, and (3) competition for extrapair mating opportunities. Song was infrequent during the non-breeding season, increased dramatically prior to nesting (17 % time spent singing), and increased even more so during nesting (32 % time spent singing). Male song output was inversely related to frequency of interactions between pairs at territorial borders; however, interactions may also serve in a mating context. Extra-pair matings were common, and 17 of 41 nestlings in ten of 19 broods were extrapair young, suggesting that high male song output may be sexually selected via extra-pair mate choice. Although males spent much less time singing prior to nesting, our results also indicate that male initiation of singing was associated with female egg-laying date, indicating also a role in within-pair coordination of reproduction. Our results suggest that high song output during the breeding season may be more common in omnivorous species that experience increased seasonality and that it may be indicative of an extra-pair mating system. More studies of species with diverse life histories are needed to examine the ecological conditions that explain interspecific variation in song output.Keywords Extra-pair mating Á Neotropics Á Pair coordination Á Seasonality Á Song output Á Year-round territoriality Zusammenfassung Die Funktion saisonalen Gesangs bei der tropischen Rotkehl-Ameisentangare (Habia fuscicauda) Aktuelle Untersuchungen von tropischen Vögeln mit ganzjähriger Territorialität deuten darauf hin, daß die Gesangsrate das ganze Jahr über relativ niedrig ist, was mit einer geringeren Saisonalität und einer relativ stabilen sozialen Umwelt über das Jahr hinweg zusammenhängt. Wir untersuchten saisonale Unterschiede in der Gesangsrate der Rotkehl-Ameisentangare (Habia fuscicauda), einer sozial monogamen Art, bei der die Männchen vor allem während der Brutsaison singen, um festzustellen, in welchem Maße eine Zunahme der Gesangsrate angeregt ist durch (1) Revierverteidigung, (2) Paarkoordination bezüglich des Nistbeginns und (3) Konkurrenz um Gelegenheiten für ,,extra-pair mating''. Der Gesang war selten außerhalb der Brutzeit, nahm dramatisch zu vor der Nistzeit (Gesang 17 % der gesamten Zeit), und umso mehr während der Nistzeit (Gesang 32 % der Gesamtzeit). Der Umfang des

Does a rival’s song elicit territorial defense in a tropical songbird, the Pied Bush Chat (Saxicola caprata)?

“…In other words, if male song increases primarily as a result of territorial defense, then seasonal song activity should be positively correlated with the territorial intrusions and escalated aggressions (Chiver et al, 2015). Such results have been reported in Song sparrows (Hyman, Hughes, Searcy, & Nowicki, 2004;Nowicki, Searcy, Krueger, & Hughes, 2002).…”

“…Despite the fact that many bird species are residents of tropical habitats, so far no avian species from Indian subcontinent has been studied to provide evidence that song can escalate response by a territory owner (Chiver, Stutchbury, & Morton, 2015;Stutchbury & Morton, 2001). Given this limitation in studying birds from only limited areas, and with the goal of providing new evidence from an unstudied species we performed a field experiment using the combination of existing playback methods and the use of a crafted model of the study species (the Pied Bush Chat).…”

Seasonality of vocal activity of a bird community in an Afrotropical lowland rain forest

“…Under these conditions, it is generally expected that singing activity is relatively constant year-round and that song is also used outside of the breeding context for territory defence (Tobias et al 2011, Topp & Mennill 2008). However, recent studies on several Neotropical species have indicated that singing activity varies throughout the year – males sing infrequently outside of the breeding season and increase their singing activity dramatically during the breeding period (Chiver et al 2015, Hill et al 2015, Koloff & Mennill 2013). Song, often performed by both sexes, also functions in stimulation of the social mate and helps in within-pair timing and the synchronization of nesting in the tropics (Chiver et al 2015, Kunkel 1974).…”

Bird songs on the shelf: assessing vocal activity and output using data hidden in sound archives

“…84 85 It is generally assumed that most birds from the temperate zone exhibit marked seasonal 86 whereas others show markedly seasonal patterns of vocal activity correlated with 93 reproduction (e.g., Negret et al 2015;Stutchbury & Morton 2001). Even in species that 94 sing constantly during the year, vocal activity may vary seasonally, increasing during the 95 breeding period (e.g., Koloff & Mennill 2012;Chiver et al 2015). 96…”