Annual molt period and seasonal color variation in the Eared Dove´s crown

PLOS ONE RESEARCH ARTICLE Annual molt period and seasonal color variation in the Eared Dove´s crown Diego J. Valdez ID1,2*, Santiago M. Benitez-Vieyra3 1 Facultad de Ciencias Exactas, Fı́sicas y Naturales, Centro de Zoologı́a Aplicada, Universidad Nacional de Córdoba, Córdoba, Argentina, 2 Consejo Nacional de Investigaciones Cientı́ficas y Técnicas (CONICET), Instituto de Diversidad y Ecologı́a Animal (IDEA), Córdoba, Argentina, 3 Instituto Multidisciplinario de Biologı́a Vegetal (IMBIV), Universidad Nacional de Córdoba–Consejo Nacional de Investigaciones Cientı́ficas y Técnicas (CONICET), Córdoba, Argentina a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 OPEN ACCESS Citation: Valdez DJ, Benitez-Vieyra SM (2023) Annual molt period and seasonal color variation in the Eared Dove´s crown. PLoS ONE 18(2): e0280819. https://doi.org/10.1371/journal. pone.0280819 Editor: Matthew Shawkey, University of Akron, UNITED STATES Received: September 15, 2022 Accepted: January 9, 2023 Published: February 24, 2023 Peer Review History: PLOS recognizes the benefits of transparency in the peer review process; therefore, we enable the publication of all of the content of peer review and author responses alongside final, published articles. The editorial history of this article is available here: https://doi.org/10.1371/journal.pone.0280819 Copyright: © 2023 Valdez, Benitez-Vieyra. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: All relevant data are within the paper and its Supporting Information files. Funding: The author(s) received no specific funding for this work. * Abstract Molting is an important process in which old and worn feathers are exchanged for new ones. Plumage color is determined by pigments such as carotenes, melanin and by the ultrastructure of the feather. The importance of plumage coloration has been widely studied in different groups of birds, generally at a particular time of the year. However, plumage coloration is not static and few studies have addressed the change in plumage color over time and its relationship to reproductive tasks. The Eared Dove (Zenaida auriculata, Des Murs, 1847) has a melanistic coloration with sexual dichromatism in different body regions. The Eared Dove´s crown is the most exposed body region during the bowing display. Our objective was therefore to accurately determine the molting period of the crown feathers and study the seasonal variation in their coloration in females and males. Our findings indicate a molting period of 6 months (January to June). The new feathers are undergoing changes in their coloration from July to December. During that period we apply an avian vision model then enabled us to reveal a seasonal variation in the coloration of the crown feathers in both sexes, as given by a change in the chromatic distances. The highest values in the chromatic distances towards the reproductive period are given by a change in the UV-violet component of the spectrum, indicating changes in the microstructure of the feather. This change in crown coloration towards the breeding season could be linked to reproductive behaviors. Introduction Molt is a key physiological process in the life history of birds, in which old and worn feathers are replaced by new ones [1, 2]. Bird plumage coloration is determined by different pigments such as carotenes, melanins and psittacofulvins, or by the ultra-structure of the feather, which generates the structural colors [2, 3]. Plumage coloration has been linked to intra- and interspecific communication processes, serving as an indicator of the “quality” of the individual for the purpose of attracting the opposite sex, as a signal to defend territory, or as camouflage [4]. Most objective studies on bird coloration focus on a particular time of the year, usually the breeding period. However, plumage coloration is not static and changes over time. Once the PLOS ONE | https://doi.org/10.1371/journal.pone.0280819 February 24, 2023 1 / 11 PLOS ONE Competing interests: The authors have declared that no competing interests exist. The eared dove´s crown coloration varies between winter and spring molt is complete, the coloration of the feathers can change throughout the year due to various factors, both biotic (bacterial activity and ectoparasites) and abiotic (mechanical abrasion, dust and fat accumulation, solar irradiation, etc.) [5–9]. Variations in plumage coloration throughout the year could affect several aspects of a bird’s life history both during non-breeding and breeding seasons (competition for food resources, male and female survival, mate choice, intra-sex competition, nesting sites, etc.). Several studies (mainly carried out on passerine species) have addressed seasonal variations in plumage coloration [6, 10–13]. Depending on the type of coloration (melanic, carotenic or structural coloration) a bird has, the pattern of color change throughout the year may differ according to the species [13]. In this context, the Eared Dove (Zenaida auriculata, Des Murs, 1847) is an opportunistic species of columbiform native to South America [14] that has a melanistic coloration type with slightly pinkish tones on the chest and belly, is gray on the back and has black spots on the face and wings [15]. Sexual dichromatism in the Eared Dove occurs in different body regions, being more evident in the crown [16], where males have around 20% more reflectance than females, with a noticeable difference in the UV region of the spectrum [16]. This is a very interesting finding since the crown is the body region most exposed during courtship [17]. The Eared Dove presents the typical bowing display common to most doves and pigeons, the male chasing the female with inflated neck and head down, thus exposing the crown, and the typical coo vocalization [17]. Although the sexual dichromatism of the Eared Dove has been addressed in detail, the studies were carried out at a specific time of the year and registered only the molting period of the primary remiges (the only molting data available at the time) [14, 16]. However, the molting period of the primary remiges is not necessarily the same as for the rest of the body, especially in the case of crown feathers. The objective of the present study was therefore to follow the molting period of crown feathers in female and male Eared Dove and determine whether there is any seasonal variation in the coloration of these feathers that is perceptible by birds. Materials and methods Permits The study meets Argentine legal requirements, was carried out in strict accordance with the Guidelines for Ethical Research on Laboratory and Farm Animals and Wildlife Species and had the prior approval of the ethics committee of CONICET (Resolution No (...truncated)