Plumage coloration differs between offspring raised in natural cavities and nestboxes

Ornithology, 2024, 141, 1–12 https://doi.org/10.1093/ornithology/ukae002 Advance access publication 12 January 2024 Research Article Plumage coloration differs between offspring raised in natural cavities and nestboxes Katarzyna Janas,1,*, Irene Di Lecce,2, Marta Szulkin,2, and Joanna Sudyka3,4, Museum and Institute of Zoology, Polish Academy of Sciences, Warsaw, Poland Institute of Evolutionary Biology, Faculty of Biology, Biological and Chemical Research Centre, University of Warsaw, Warsaw, Poland 3 Institute of Environmental Sciences, Jagiellonian University, Kraków, Poland 4 Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands 1 2 ABSTRACT Most of our knowledge of secondary hole-nesting birds comes from populations breeding in human-provided nestboxes, yet these might differ from natural cavities in a number of parameters, including internal dimensions or microclimate, leading to differences in reproductive ecology. Here, we demonstrate differences in plumage coloration, an important visual signal of individual quality, in Blue Tit (Cyanistes caeruleus) and Great Tit (Parus major) nestlings raised in natural cavities and nestboxes. For this study, we collected feather samples over two breeding seasons and applied reflectance spectrophotometry to calculate color metrics. Carotenoid chroma was higher in nestbox-reared Blue Tits, whereas brightness was higher in nestbox-reared Great Tits (with a similar tendency for Blue Tits). The latter result might be explained by the better nutritional condition of Great Tit nestlings raised in nestboxes. Furthermore, we found no evidence for preference of adults expressing more elaborate plumage towards a specific cavity type in either species. Consequently, we assume that differences in nestling plumage reported here are driven by rearing conditions (nestboxes vs. natural cavities) and not by differences in plumage-based parental quality. Our study adds to the growing body of evidence confirming that anthropogenic environmental modifiers, such as nestboxes, might influence avian physiology and the resulting phenotype. Keywords: plumage carotenoid-based coloration, natural cavities, nestboxes, Blue Tit, Great Tit, Cyanistes caeruleus, Parus major, carotenoid chroma, brightness How to Cite Janas, K., I. Di Lecce, M. Szulkin, and J. Sudyka (2024). Plumage coloration differs between offspring raised in natural cavities and nestboxes. Ornithology 141:ukae002. LAY SUMMARY •Natural cavities and nestboxes differ in many ways, including dimensions and microclimatic conditions, which can have consequences for predation risk and avian reproductive success. •Currently, knowledge on plumage color of hole-nesters comes solely from studies on populations breeding in nestboxes or aviaries. So far, no study tested whether such results hold for birds breeding in natural cavities. To fill this gap, we examined the impact of rearing cavity type— natural cavities vs. artificial cavities (nestboxes) on carotenoid-based coloration of Blue Tit (Cyanistes caeruleus) and Great Tit (Parus major) nestlings. •We found that Blue Tit nestlings expressed plumage with more saturated color in nestboxes, whereas in Great Tits nestlings raised in nestboxes expressed brighter plumage. •Our results add to the growing body of evidence that differences between natural cavities and nestboxes can bear consequences for nestling physiology and phenotype. La coloration du plumage diffère entre les oisillons élevés dans des cavités naturelles et ceux élevés dans des nichoirs RÉSUMÉ La plupart de nos connaissances sur les oiseaux cavicoles secondaires proviennent de populations se reproduisant dans des nichoirs artificiels, mais ceux-ci peuvent différer des cavités naturelles d’un certain nombre de paramètres, incluant les dimensions internes ou le microclimat, ce qui entraîne des différences dans l’écologie de la reproduction. Dans cette étude, nous démontrons qu’il existe des différences dans la coloration du plumage, un signal visuel important de la qualité individuelle, chez les oisillons de Cyanistes caeruleus et Parus major élevés dans des cavités naturelles et dans des nichoirs. Nous avons collecté des échantillons de plumes pendant deux Submission Date: June 2, 2023. Editorial Acceptance Date: December 15, 2023 © American Ornithological Society 2024. Published by Oxford University Press for the American Ornithological Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial License ((https://creativecommons.org/ licenses/by/4.0/)), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact Correspondence author: * 2 Cavity type impacts plumage coloration K. Janas et al. saisons de reproduction et nous avons appliqué la spectrophotométrie de réflectance pour calculer les paramètres de la couleur. La saturation des couleurs des caroténoïdes était plus élevée chez les oisillons de C. caeruleus élevés dans des nichoirs, alors que la brillance était plus élevée chez les oisillons de P. major élevés dans des nichoirs (avec une tendance similaire pour C. caeruleus). Ce dernier résultat pourrait s’expliquer par le meilleur état nutritionnel des oisillons de P. major élevés dans des nichoirs. En outre, nous n’avons trouvé aucune preuve de la préférence des adultes au plumage plus élaboré pour un type de cavité spécifique chez l’une ou l’autre de ces espèces. Par conséquent, nous supposons que les différences de plumage chez les oisillons sont dues aux conditions d’élevage (nichoirs vs cavités naturelles) et non à des différences de qualité parentale basées sur le plumage. Notre étude s’ajoute au nombre croissant de preuves confirmant que les modificateurs environnementaux anthropogéniques, tels que les nichoirs, peuvent influencer la physiologie aviaire et le phénotype qui en résulte. Mots-clés: coloration du plumage basée sur les caroténoïdes, cavités naturelles, nichoirs, Cyanistes caeruleus, Parus major, saturation des couleurs des caroténoïdes, brillance INTRODUCTION Anthropogenic activities can lead to the disappearance or deterioration of natural habitats (Chamberlain et al. 2009). The shortage of old forest stands, leading to a scarcity of natural cavities they offer, is often mitigated by providing nestboxes, readily used by some birds, such as Great Tits (Parus major) and Blue Tits (Cyanistes caeruleus) (Mänd et al. 2005). For researchers, nestbox provisioning can facilitate the acquisition of larger sample sizes (Wesołowski 2011, Maziarz et al. 2017, Sudyka et al. 2022). However, the reproductive ecology of birds using nestboxes differs from those using natural cavities in some essential parameters, including earlier breeding dates, accelerated onset of incubation (Fargallo et al. 2001, Czeszczewik 2004, Sudyka et al. 2022; (...truncated)