DOI: 10.5061/dryad.qbzkh18w2
title: Urbanization enhances ornament expression in a common waterbird

description: In birds, many components of visual communication (i.e. plumage and
 non-plumage ornaments) play an important role in signaling of individual
 quality. It is widely acknowledged that ornament expression may be
 modulated by environmental conditions, however, it remains relatively
 poorly explored whether and how urbanization affects the expression of
 non-plumage ornamentation in urban dwelling-individuals. Here, we
 investigated the effect of urbanization on the expression of bare-part
 (non-plumage) putative ornament (i.e., the frontal shield size) across
 eight populations of a common reed-nesting waterbird, the Eurasian coot
 Fulica atra. Most importantly, we found robust support for the positive
 effect of urbanization on shield size and its condition-dependent
 character in coots. Also, long-term monitoring of a single urban
 population revealed relationships between the ornament expression and nest
 site selection patterns, as coots with larger shields were bold enough to
 colonize more anthropogenically transformed urban sites with stronger
 human disturbance and better accessibility to anthropogenic food. At the
 same time, we found no support for associations between the shield size
 and either nest defense behavior or reproductive performance in coots,
 likely reflecting stochasticity of anthropogenic selective pressures. To
 our knowledge, this study provides the first evidence for the enhanced
 expression of an unpigmented non-plumage putative ornament in
 urban-dwelling birds. Our results show that the effects of urbanization on
 non-plumage components of quality signaling in birds may be complex and
 multifaceted, and reinforces a need for further investigation focusing on
 different types of ornamentation across divergent avian species.
description: # Urbanization enhances ornament expression in a common waterbird ##
 Description of the data and file structure Files and variables
 Description: File: Raw_Data_1.xlsx The data on frontal shield size,
 condition, and physiological stress were collected for 485 Eurasian coots
 (541 capture occasions) from eight paired populations (four urban and four
 nonurban) across Poland during 11 breeding seasons (years: 2012 - 2023).
 File: Raw_Data_2.xlsx The data on nest defence behaviour were collected
 for 128 Eurasian coots (204 experiments) from one urban population (Łódź)
 during 11 breeding seasons (years: 2012 - 2023). File: Raw_Data_3.xlsx
 Data on nest site selection and reproductive performance were collected
 for 182 Eurasian coots (211 breeding attempts) from one urban population
 (Łódź) during 11 breeding seasons (years: 2012 - 2023). Variables * ID:
 Individual identity. * Capture date: Date of bird capture and measurement
 collection (day of the year). * Urbanization: The level of urbanization
 (Urban - an individual was sampled from one of the four urban populations,
 Nonurban - an individual was sampled from one of the four nonurban
 populations) * Population pair: The population pair from which the
 individual was sampled (Warszawa, Poznań, Katowice, Łódź). * Year: The
 year in which the individual was captured and measured. * Sex: The sex of
 the individual (F - female, M - male). * Wing length (mm): The wing length
 was measured from the carpal joint (the bend of the wing) to the tip of
 the longest primary feathers with a stopped ruler. Wing length was
 included as a linear predictor of body mass in the statistical models. *
 Frontal shield size (PC1): The shield size was calculated using two
 measurements (length and width), which were combined into a single
 univariate parameter (PC1) using principal component analysis (PCA). PC1
 was standardised to z scores separately for males (M) and females (F). *
 Body mass (g): Body mass was measured using an electronic balance. *
 Haemoglobin concentration (g/l): Haemoglobin concentration, used as
 condition index, was measured with HemoCue Hb 201+ portable photometer. *
 Size-corrected body mass: Size-corrected body mass, used as condition
 index, was calculated as Scaled Mass Index (SMI) according to Peig and
 Green (2009). * H/L ratio: The H/L ratio (used as physiological stress
 index) was calculated as the proportion of heterophils (H) to lymphocytes
 (L). * Experiment date: Date of the experiment (day of the year). *
 Breeding status: Breeding attempts of captured birds, including first and
 second or renest (repeated after brood failure) broods, coded as a binary
 trait (0 - first brood; 1 - second/renest brood). * Incubation stage
 (days): The interval between the laying date and the date of the
 experiment. * Nest defence - presence: The presence or absence of
 aggressive nest defence (approach with threat posture, alarm vocalization,
 or splattering display) against a human intruder (experimenter) at the
 nest site (coded as binary trait: 0 - absence of nest defence, 1 -
 presence of nest defence). * Nest defence - approach distance (m): The
 minimum distance at which a bird approaches human intruder (experimenter)
 during nest defence at the nest site. * Laying date: Date of laying the
 first egg (day of the year). * Distance from nest to shore (m): The
 distance from the nest to the shore. * Distance from nest to open water
 (m): The distance from the nest to the open water (set to zero if the nest
 was located outside emergent vegetation). * Water depth (m): The water
 depth at the nest. * Clutch size: The number of laid eggs. * Hatching
 success: Hatching of at least one chick (1) or hatching no chicks (0). *
 Breeding success: Raising (fledging) of at least one chick (1) or rasining
 no chicks (0). * No. raised chicks: The number of raised chicks assessed
 visually (with binoculars) for all broods after 4-6 weeks from hatching.
 Missing values marked as "NA". ## Code/software All computations
 were performed in R v.4.2.3 statistical environment.