Diel and seasonal patterns of variation in the singing behaviour of Savannah Sparrows (Passerculus sandwichensis)

Abstract

Background: The vocalizations of birds are dynamic traits that often vary in output with time of day and time of year. By quantifying patterns of diel and seasonal variation in vocal output, we can gain insight into the ecology and evolution of birds and the function of their vocalizations. In this investigation, we quantified diel and seasonal variation in song output by studying a breeding population of Savannah Sparrows (Passerculus sandwichensis). Methods: We used autonomous recorders to collect extensive recordings across the breeding season in a long-term, colour-marked study population of Savannah Sparrows in eastern Canada. We described diel and seasonal variation across five different breeding stages based on recordings of more than 50,000 songs from 34 males. Results: During the pre-breeding stage, prior to female arrival, males sang a pronounced dawn chorus with a peak in song output during the early morning. During the breeding stage, in contrast, the dawn chorus was diminished and males instead exhibited a pronounced dusk chorus with a peak in song output during the evening. Across the breeding season, the highest levels of song output occurred in late April and early May, soon after males arrived on the breeding grounds, and the lowest levels occurred in August, prior to the departure of birds for the wintering grounds. Conclusions: These patterns suggest that Savannah Sparrows' early-season dawn choruses are directed at males and serve a territorial defense function. Later-season dusk choruses, in contrast, appear to play a role in attracting mates and possibly acoustic mate guarding.

Quantifying song behavior in a free‐living, light‐weight, mobile bird using accelerometers

“…The “churring” song of nightjars is powerful and less complex than many other bird songs, which will facilitate the investigation of new questions regarding intra‐ and inter‐individual variation in song output in response to internal (e.g., mating status, age, and body condition) and/or environmental factors (e.g., lunar cycle, weather conditions, and artificial light) that contribute to individual‐ and population‐level variation in song output. For example, to unravel the functions of song (mate attraction and/or territory defense), it is important to know how song expression varies between pairing and breeding stages (Gienapp & Merilä, 2010; Moran et al, 2019). This seasonal variation in song activity can be strongly affected by weather factors (Bruni et al, 2014; Hasan, 2010; Keast, 1994; Naguib et al, 2019; Schäfer et al, 2017) and the lunar cycle (Alonso et al, 2021; Dickerson et al, 2020; York et al, 2014).…”

“…It may be interesting to investigate, test, and validate how alternative logger placements may be useful to detect vibrational signals or body movement associated with vocal communication in birds with more complex song types (Alonso et al, 2021;Gudka et al, 2019). With to unravel the functions of song (mate attraction and/or territory defense), it is important to know how song expression varies between pairing and breeding stages (Gienapp & Merilä, 2010;Moran et al, 2019). This seasonal variation in song activity can be strongly affected by weather factors (Bruni et al, 2014;Hasan, 2010;Keast, 1994;Naguib et al, 2019;Schäfer et al, 2017) and the lunar cycle (Alonso et al, 2021;Dickerson et al, 2020;York et al, 2014).…”

The relationships of breeding stage to daytime singing behaviour and song perch height in Bermuda white‐eyed vireosVireo griseus bermudianus

“…Bachelor males often sing at higher rates at dawn (e.g. savannah sparrows, Passerculus sandwichensis ; Moran et al 2019), but then reduce daytime song once paired (e.g. chipping sparrows, Spizella passerine ; Liu and Kroodsma 2007).…”

Singing behaviour of ruby‐crowned kinglets Regulus calendula in relation to time‐of‐day, time‐of‐year and social context

“…dawn chorus), which has been attributed to intrinsic traits of the signaller, and social and environmental selective pressures (reviewed by Staicer et al ). However, descriptions of diel singing activity are often overlooked (but see Sosa‐López and Mennill , Moran et al ). Taken together, descriptions of diel and seasonal patterns of singing behaviour provide a basis for developing hypotheses about the selective forces that have shaped temporal patterns in birdsong.…”