DOI: 10.5061/dryad.bnzs7h4kc
title: Comparisons of acoustic structures between sexes in a duetting, montane bird

description: Female song in birds is more widespread than previously thought, and
 studies across different species are critical for better understanding the
 entire evolutionary process of bird song. In this study, we recorded the
 songs of males and females in a duetting, montane bird species, the
 Elliot’s laughingthrush Trochalopteron elliotii, across consecutive
 breeding seasons. We specifically focused on identifying the number and
 structure of different song types by males and females, and compared these
 acoustic structures between the sexes. Our findings revealed that both
 males and females sang sex-specific solos. More specifically, females sang
 a single type of solo that varied significantly in the number of notes,
 whereas males produced three different solos composed of 2, 3, or 4 notes,
 respectively. Female solos exhibited significantly more notes and longer
 song duration compared to males. Male solos typically had a significantly
 higher maximum frequency for the entire song. No significant differences
 were observed in the duration of the first note, song rate, and other
 frequency characteristics between male and female solos. Furthermore,
 paired males and females coordinated their sex-specific solos to form
 duets when challenged by conspecific territory intruders, both within and
 outside the breeding season. Sex-specific solos suggested that male and
 female songs play different roles and may be subject to different
 selective pressures. Further research is necessary for elucidating the
 functions of male song, female song, and duets in this montane bird
 species.
description: <strong>Study site and species</strong>
 The fieldwork was conducted in the Lianhuashan Nature Reserve
 (34°58′16″ N, 103°45′30″ E; 2040 m a.s.l.), located on the eastern edge of
 the Qinghai-Tibet Plateau in central China. The study area is mainly
 composed of cultivated farmlands, open woodlands, and orchards, as well as
 abandoned fields dominated by scrub vegetation. Since 2013, we have been
 studying the ecology of the resident Elliot’s laughingthrush population at
 this site and each year, catch and colour-band males and females with a
 unique combination of colour rings for sex and individual identification.
 The sex of all marked individuals was determined by the swelling of the
 male gonads and differences in morphological size (Liu and Sun
 2016). <strong>Field observation and vocalization
 recording</strong><strong> </strong>
 From March 5 to May 20, 2021, and April 5 to June 13, 2022, we
 observed male and female singing behaviour every three days during
 suitable weather conditions. All observations were conducted between 08:00
 and 11:00 am. Within each territory, we conducted one-hour long
 observations, during which we recorded the date, sex of the singer, time,
 singing contexts (agonistic interactions, spontaneous singing, chorus
 singing), presence of intruders, and whether the focal pair divorced. For
 each singing individual, we collected solos and duets using a TASCAMHD-P2
 sound recorder (44.1 kHz, 16 bits) and a Sennheiser MKH416 P48 shotgun
 microphone at a distance of 5-10 meters from the singing birds. We also
 recorded solos from unpaired males, which were determined through direct
 observations of male-female interactions, and from observations made at
 nests being attended by these same males.
 <strong>Acoustic structure</strong>
 Avisoft-SASLab Pro was used to analyse the song structure of all
 recordings. The sampling rate was 22.05 kHz, with a sample size of 16
 bits, the FFT length was 512 points, the frequency resolution was 43 Hz,
 the temporal resolution was 2.9 ms, and the window used was FlatTop, with
 an 87.5% overlap. The simplest elements of the song on the sonogram are
 referred to as “notes”. We defined a discrete song as being made up of two
 or more consecutive notes, typically separated by a brief pause (Brenowitz
 et al. 1997). Solo songs refer to the distinctive individual songs
 produced by a single bird (either male or female). All definitions of
 songs and notes are illustrated in Figure 1A. For each
 individual, the following song characteristics were recorded: the total
 number of notes within a song, duration of song, first note duration of a
 song, the speed of a song (the number of notes within a song per second),
 maximum frequency, minimum frequency, and frequency range of the song, the
 first and last note. To determine these parameters, we analysed two solos
 from each female and male. In order to include a diverse range of
 variation in vocal characteristics within individuals, we only selected
 recordings that were both high-quality and representative of the
 individual’s vocal repertoire.
 <strong>Spectrograms creation</strong>
 Spectrograms were extracted using R package
 '<em>Seewave'</em> with an FFT-window length of 512
 and an overlap of 87.5% (Sueur et al. 2008). The
 '<em>tuneR'</em> package was used to load sound
 files in WAV format as an object (Ligges et al. 2013). In a spectrogram,
 time is displayed on the x-axis, frequency on the y-axis, and amplitude is
 represented by colour intensity.
 <strong>Statistical analysis</strong>
 Wilcoxon rank sum tests were used to determine if each of the
 vocal characteristics (the number of notes, speed, duration, first note
 duration) and frequency of the song differed between males and females.
 Bonferroni correction was used to adjust the p-values in the analysis. All
 statistical analyses were conducted using R version 4.1.3 (R Core Team,
 2022). Values are given as Mean ± SE, with Bonferroni corrected
 <em>P </em>value &lt; 0.004.
description: # Comparisons of acoustic structures between sexes in a duetting, montane
 bird
 [https://doi.org/10.1111/jav.03249](https://doi.org/10.5061/dryad.bnzs7h4kc) Data for comparisons of temporal characteristics and frequency of male and female song.  ## Description of the data and file structure Abbreviations in the data file: * DurationS: duration of the whole song (s), * Duration1: first note duration of a song (s), * Note: number of notes within a song, * Speed: the speed of the whole song (the number of notes within a song per second), * MaxF: maximum frequency of the song (kHz), * MinF: minimum frequency of the song (kHz), * RangeF: frequency range of the song (kHz),  * Max1: maximum frequency of the first note (kHz), * Min1: minimum frequency of the first note (kHz), * Range1: frequency range of the first note (kHz), * Max0: maximum frequency of the last note (kHz), * Min0: minimum frequency of the last note (kHz), * Range0:  frequency range of the last note (kHz).