DOI: 10.5061/dryad.cnp5hqchb
title: A comparative analysis of song amplitude across and within bird species

description: Animals use acoustic signals to exchange information essential to their
 survival and reproduction. A crucial parameter in acoustic communication
 is the amplitude of the signal, as it plays a decisive role in signal
 transmission and can also encode information. However, signal amplitude
 has been largely neglected in animal communication studies because it is
 difficult to assess. We measured song amplitudes in 17 European songbird
 species (Passeriformes) in the field and investigated the sources of
 variation between and within species. We found that song amplitude
 increased with increasing background noise (Lombard effect), in the
 presence of singing rival males, and it varied with the time of day. These
 findings highlight that birds can adjust how loud they sing in response to
 changes in the biotic and abiotic environment. However, our
 phylogenetically informed analysis found no support for the long-standing
 hypotheses that song amplitude reflects body size or territory size across
 bird species. We suggest that the variation of song amplitude between
 species is related to differences in ecology, in the strength of sexual
 selection, and in the costs of singing loudly rather than to body size, as
 suggested before.
description: # A comparative analysis of song amplitude across and within bird species
 Dataset DOI: [10.5061/dryad.cnp5hqchb](10.5061/dryad.cnp5hqchb) ##
 Description of the data and file structure This readme.txt file was
 generated on 2024-07-17 by Léna de Framond Author Information: Name:
 Brumm, Henrik Institution: Max Planck Institute for Biological
 Intelligence, Animal Communication & Urban Ecology Group Email:
 henrik.brumm@bi.mpg.de Name: De Framond, Eric Institution: Max Planck
 Institute for Biological Intelligence, Animal Communication & Urban
 Ecology Group Email: eric.de.framond@laposte.net Name: Kikodze, Ekaterine
 Institution: Max Planck Institute for Biological Intelligence, Animal
 Communication & Urban Ecology Group Email: kato.kikodze@gmail.com
 Name: De Framond, Léna Institution: Max Planck Institute for Biological
 Intelligence, Animal Communication & Urban Ecology Group Email:
 lena.framond@bi.mpg.de Date of data collection: 2010-2023 ### Files and
 variables #### File: SongAmplData.csv **Description:** raw data used for
 the analysis ##### Variables * BirdID: Unique identifier for each bird *
 English_name: Bird species (English) * Latin_name: Bird species
 (scientific) * recordist: Identifier for the recordist * date: Recording
 date (yyyy-mm-dd) * time: Recording hour (hhmm) * lat: Latitude (decimal
 degrees) of recording point * long: Longitude (decimal degrees) of the
 recording point * sunrise: Sunrise time (hour) on the day of recording *
 t_after_sunrise: Time of recording (hours after sunrise) * fliptime:
 Recording time in hours relative to dawn (for morning recordings) or dusk
 (for afternoon recordings) * temperature: Ambient temperature at the time
 of recording (degrees Celsius) * humidity: Ambient relative humidity at
 the time of recording (percent) * wind_beaufort: Wind force at the time of
 recording (Beaufort) * nmales: Presence of singing conspecific males at
 the time of recording (Yes = 1, No = 0) * ambient_noise: Ambient noise
 amplitude (dB (A) SPL) * RL_song_spl_a: Received level of song amplitude
 (dB (A) SPL) * recording_distance: Distance between the recordist and the
 bird (m) * SL_song_spl_1m: Source level of the song (dB(A) SPL) corrected
 for spherical spreading * weight: Species-specific average weight (grams)
 * wing_length_ab: Species-specific wing span (mm) * weight_ab:
 Species-specific mean weight (grams) * tarsus_lg_ab: Species-specific
 tarsus length (mm) * wing_sp: Species-specific wing length (mm) *
 tail_lg_ab: Species-specific tail length (mm) * max_npairs_10Ha:
 Species-specific maximum number of pairs per 10 hectares * PC_bodysize:
 PC1 of PCA including wing length, tarsus length, and body mass, used as a
 composite measure of body size #### File:
 SongAmplAnalysis\_perSpecies\_forRep.Rmd **Description:** R code used for
 the analysis of within-species parameters #### File:
 SongAmplAnalysis\_forRep.Rmd **Description:** R code used for the analysis
 of across-species parameters #### File: output.nex
 **Description:** Phylogenetic tree of the twelve species used in the
 across-species analysis ## Code/software R scripts have been run with R
 version 4.2.2, 2023. package versions: ape 5.7-1 bayespot 1.10.0 brms
 2.19.0 datelife 0.6.8 datelifeplot 0.2.2 devtools 2.4.5 dplyr 1.1.1
 ggeffects 1.2.0 ggplot2 3.4.1 phytools 2.1-1 rotl 3.1.0 tidyverse 2.0.0