Seasonal and diurnal variation of vocal behaviour in duetting White-browed Sparrow Weavers

Abstract

Singing in tropical and Southern hemisphere birds often occurs throughout the year in the form of duetting, which is thought to be associated with year-round territoriality. Whitebrowed Sparrow Weavers (Plocepasser mahali) are cooperatively breeding songbirds of Eastern and Southern Africa, which live in groups of 2-10 individuals and defend all-purpose territories year-round. Their vocal behaviour is extraordinary as all group members sing duet and chorus song, but the dominant male of the group, additionally, sings a long solo song at dawn that comprises a distinct syllable repertoire. To gain further insight into the functions of the different types of song, the present study aimed at providing detailed quantitative data on diurnal and seasonal variation in singing activity. Therefore, we monitored the song behaviour of five groups of White-browed Sparrow Weavers at several time points during the course of the day and during the course of the year in relation to the groups' breeding activities and environmental variables such as photoperiod, temperature and rainfall. Diurnally, solo song was heard exclusively during the first hour of vocalization in the morning before the onset of duetting. Seasonally, solo singing was restricted to the summer months. No tight link with breeding activities was found. Solo song duration was related to the density of neighbouring groups but not to group size. Similarly, duet/chorus rate showed large variation between groups and was related to the density of neighbouring groups. Diurnally, duet/chorus rate was significantly higher at the time point wake-up than at other times of the day. Seasonally, there was no difference. The increased singing rate at the time point wake-up, when all birds are present in the territory, suggests that these songs might convey information about territory ownership, group size as well as sex and status of the individuals.

Actividad de vocalización del Burgo (Momotus momota) en la Selva pedemontana de Yungas del Parque Nacional Calilegua

“…Esto puede deberse a lo reportado en otras especies de aves, en donde la iluminación lunar y el avance de la luz del alba podrían estar facilitando la comunicación entre individuos (La, 2012;York et al, 2014). Esto se ve reflejado en el tipo de vocalización que fue registrada (canto de reclamo o llamado), que también ha sido reportado para otras especies de aves, ya sea para dar aviso ante otras especies, presencia de posibles depredadores, búsqueda de alimento, delimitación de territorio, cortejo o la interacción entre adultos y pichones hacia finales del periodo reproductivo (La, 2012;York et al, 2014;Voigt et al, 2021). Respecto a las precipitaciones, diferentes trabajos han registrado que las aves vocalizan menos durante la lluvia, ya que la trasmisión del sonido no es eficiente debido a la interferencia acústica provocada por las tormentas (Vokurková et al, 2018).…”

“…El comportamiento de vocalización diurno de las aves puede estar determinado por la estacionalidad (época del año) y la hora del día; como así también a posibles influencias de condiciones climáticas (e.g. lluvias, temperatura, humedad), el establecimiento de territorios para atraer parejas, para localizar alimento o alertar sobre la presencia de posibles depredadores (Keast 1994;La 2012;Voigt et al, 2021). Las especies de aves diurnas vocalizan mayormente al amanecer y al atardecer, cuando los niveles de luz solar son bajos; como así también, debido a que las bajas temperaturas en estos momentos del día hacen más efectiva la transmisión del sonido (Clark 2012;Mei et al, 2022).…”

Temporal Patterns of Cooing Activity of the European Turtle-Dove Streptopelia turtur: Optimising Monitoring Schemes Based on Abundance Indices

“…A similar pattern was also observed by Gutiérrez-Galán (2016), who found that the average duration of silence between singing bouts was longer for densities of less than three singing males than for males at higher densities. Social stimulation of singing, with more intense singing activity in the presence of other singing males, has been also observed in other species (Sexton et al ., 2007; Alldredge et al , 2007b; Voigt et al, 2021).…”

“…Bird courtship vocalisations are markedly seasonal and daytime variations in singing activity also occur (e.g. Palmeirim & Rabaça, 1994; Ralph et al , 1995; Amrhein et al , 2007; Jakob & Ponce-Boutin, 2013; Voigt et al , 2021), making direct comparisons of estimates obtained at different times inappropriate (Schmidt et al , 2013). Assessment of singing activity temporal patterns may thus allow the best time for carrying out abundance surveys to be determined and may also help to account for differences among estimates when information has to be gathered over an extended period (Palmeirim & Rabaça, 1994; Amrhein et al , 2007).…”

A dawn and dusk chorus will emerge if males sing in the absence of their mate

“…In the rare cases where they do (e.g. in the buff-breasted wren Thryothorus leucotis [88] and the white-browed weaver Plocepasser mahali [89]), the dawn chorus is produced by the male [2]. The male-initiated dawn chorus may then be followed by a duet if the female joins the male after she emerges from the roost, which may in turn lead to a peak of duetting at dawn as observed in the rufous-naped wren [90].…”