BUSCADOR RECOLECTA

Dataset 1 includes weekly estimations of median, maximum, minimum and range values of temperature and humidity in nest boxes, for three locations, two experimental treatments and in relation to dormice presence in February., Dataset 2 includes daily differences (between 9:00 am and 3:00 am) in temperature and humidity of open nest boxes occupied or not by dormice., Dataset 3 describes Carnus emergence patterns from each sample of nest material, including number of emerged flies (Carnus abundance), date of first emergence and emergence duration., Dataset 4 includes intensity of parasitism suffered by hoopoe nestlings during the breeding season after the experiment, showing number of Carnus, hatching date, brood size and nestling age., The dataset contains data collected in Guadix, Granada (southeast Spain) in 2020, in the framework of a research to evaluate the effects of overwinter occupancy of nest cavities on the incidence of ectoparasitism suffered by hoopoes (Upupa epops) in the next breeding season., The research group benefited from grants CGL2017-83103-P, CGL2017-89063-P, PGC2018-097426-B-C22, and PID2020-117429GB-C21 funded by MCIN/AEI/ 10.13039/501100011033 and by “ERDF A way of making Europe”. AJGN was funded by the Spanish Ministerio de Ciencia, Innovación y Universidades (Programa de Formación de Personal Investigador JAE Intro). GT was supported by the Ramón y Cajal Programme (RYC-2013-13040)., Peer reviewed

Additional file 1: Table S1. Sample size of avian nests used to estimate prevalence of extra-pair paternity of the 60 bird species used in the study., Spanish Ministerio de Ciencia, Innovación y Universidades and European (FEDER), Peer reviewed

Sexually selected signals reliably reflect individual phenotypic or genetic quality and, thus, survival prospects of holders. Telomere length is considered a good predictor of life expectancy and, consequently, exploring the links between telomere length and sexually selected traits is much needed to better understand the mechanisms that maintain the honesty of sexual signals. We manipulated the length of throat feathers in spotless starling (Sturnus unicolor) males (a sexually selected signal) before reproduction and explored its effects on telomere shortening and breeding performance in subsequent reproductive events. We did not detect an effect of the feathers clipping manipulation, but males with longer throat feathers before the experiment had shorter telomeres that also shortened more slowly than those of males with shorter throat feathers did. Moreover, length of throat feathers of males before manipulation was positively related to hatching success of second clutches. Thus, correlative but not experimental results support the expected associations between sexually selected signals, telomeres and reproduction. We discuss such results in scenarios of sexual selection where feather length reflects, but does not directly cause, telomere attrition and enhanced reproductive success. Males with longer throat feathers might be older, more experienced males (i.e., with shorter telomeres), able to buffer telomere shortening between reproductive events. Because of the absence of experimental effects, differential incubation effort of females cannot explain the detected association with hatching success, but other sexually selected traits that covary with throat-feather length could be responsible. Exploring those physiological and/or morphological characteristics related to throat-feather length should therefore be the matter of future research, This work was supported by the currently named Ministerio de Ciencia, Innovación y Universidades and European (FEDER) funds (CGL2013-48193-C3-1-P, CGL2017-83103-P, CGL2017-89063-P, CGL2015-65055-P and PGC2018-095704-B-100). MAG was financed by a predoctoral contract (BES-2014-068661) from the Spanish Ministerio de Economía y Competitividad, and GT by the Ramón y Cajal Programme., Reproductive data; Telomere data, Peer reviewed

Data file includes (i) average values of melanised (M) and non-melanised (NM) feather wear of nestling birds that grew in different nests. The file also included (ii) information of feather mass degradability of nestlings and adult birds from different nests and species estimated as the olipeptide concentration (μg x mL1) of tubes containing 4mL of PBS buffer and a colony Bacillus licheniformis D13 after 21 days of incubation at 37 ºC in constant agitation at 120 rpm in an orbital agitator (VWR, Spain). The third excel sheet contain information of bacterial loads in terms of terms of mesophilic bacteria (TSA), Enterobacteriaceae (HK), Staphylococcus (VJ), and Enterococcus (KF), and average wear of melanised (M) and non-melanised (NM) wing feathers of nestlings that grew in the same nests where bacterial loads were estimated. The last excel file contain information on feather wear of melanised and non-melanised feathers of each sampled nestlings and adult. All these data were collected the Guadix region (southern Spain) and used to perform the statistical analyses in Tables 2 and 3 in Azcárate et al. 2020 (Doi: 10.1111/jav.02320)., This work was supported by the currently named Ministerio de Ciencia, Innovación y Universidades and European (FEDER) funds (CGL2013-48193-C3-1-P, CGL2013-48193-C3-2-P, CGL2013-48193-C3-3-P, CGL2017-83103-P). MAG and SDL were financed by predoctoral contracts (BES-2014-068661, BES-2014-069116) from the Spanish Ministerio de Economía y Competitividad., Peer reviewed

Study area and study species The study was conducted during the years 2015, 2016 and 2017 in a south-eastern region of Spain (Hoya de Guadix, 37º15’N, 3º01’W), where nest-boxes attached to tree trunks or walls at 3–4 m above-ground are available for starlings to breed in (for further information on the study area see Soler et al. (2017)). In the studied starling population, the reproductive season starts in early April and most individuals lay a second clutch during May-June. The most common clutch size is 62 plants to the nest, which have been shown to have antimicrobial-beneficial functions4-5 eggs. Here, we will focus on the colouration of the base of the beak, a trait with a more marked sexual differentiation as we can see in its reflectance at different wavelengths (Fig. 1). Fieldwork and experimental procedure In this population, courtship activity (e.g. singing, introducing fresh green plants and feathers in nest boxes) starts in February, more than one month before egg laying (pers. obs.). During this period, some birds roost in nest-boxes and we take advantage ofthis fact for conducting yearly bird trapping sessions in the study area (twice a year between February and mid-March). One hour before dawn, we closed the entrance of all nest boxes in the study area, and immediately after dawn, we captured by hand all individuals found roosting inside. Captured birds were kept individually in clean cotton bags hanging from a stick to keep birds quiet, and were released immediately after sampling. The maximum time that a captured starling was in the bag did never exced three hours. We explored the possible effect of time that birds were kept in the bag on bird colouration and body condition measures of the males that we recaptured by classifying them as being kept in the bag less than 1 hour (N(males) = 10), between 1 and 2 hours (N = 5), and between 2 and 3 hours (N = 7). After controlling for the effect of date of first and last capture, time between captures, treatment and size of throat feathers in the first capture, results showed that retaining time 184 in first captures did not significantly affect blue, red-yellow, or brightness colouration of the beak of males (F1,15 < 2.66, P > 0.124), nor body condition (F1, 10 = 2.19, P = 0.170) in subsequent captures. It neither had any apparent long-term consequences (see Ruiz-Rodríguez et al. (2015)), nor imply apparent negative effects on breeding performance of captured birds (Soler et al. 2008), This work was supported by the currently named Ministerio de Ciencia,es and European (FEDER) funds (GL2013C-48193-C3-1-P, CGL2017-83103-P Innovación Universidad, CGL2017-89063-P). MAG was financed by a predoctoral contract (BES-2014-068661) from the Spanish Ministerio de Economía y Competitividad, and GT by the Ramón y Cajal Programme, Peer reviewed

Avian brood parasites are expected to select host nests according to characteristics that maximize offspring fitness, such as reduced probability of ectoparasitism. Spotless starlings (Sturnus unicolor) lay immaculate blue eggs that sometimes become brownish- spotted due to the activity of the ectoparasitic fly Carnus hemapterus on incubating birds. Therefore, conspecific parasitic females should adaptively avoid nests with spotted eggshells for parasitism. Here, we manipulated perceived risk of ectoparasitism by painting the eggs with either brown spots (similar to those due to ectoparasite activity), or blue spots. A third group of nests was maintained with immaculate eggshells. Nests with non-spotted eggshells showed the highest rate of brood parasitism, while nests with brownish or bluish spots on the eggshells were parasitized at a similar lower rate. These results suggest that brood parasitic females use the presence of spots on the eggshells in their selection of host nests. This study adds to the scarce evidence showing that brood parasitic birds select host nests with low risk of ectoparasitism and demonstrates that colour patterns of the eggshell (i.e. spottiness) of their potential hosts represent a major cue employed to appraise risk of ectoparasitism, Peer reviewed

Dataset used in Tomás et al. (2020): (DOI: 10.1111/jav.02427). Data were collected in the Hoya de Guadix in 2012 in spotless starling (Sturnus unicolor) nests in the framework of an experiment to evaluate whether distance to the cavity entrance and nest size influence the risk of ectoparasitism in avian nests. Dataset includes hatching date, brood size, mean nestling body mass, microclimate of the cavity, as well as ectoparasite abundance and distance between the nest and the cavity entrance before and after experimental manipulation., Dataset used in Tomás et al. (2020): (DOI: 10.1111/jav.02427). It contains data collected in Guadix in 2012 in the framework of an experiment to evaluate whether distance to the cavity entrance and nest size influence the risk of ectoparasitism in avian nests., Financial support was provided by grants from Spanish Ministerio de Ciencia e Innovación (MCI) and FEDER (CGL2010-19233-C03-01), from Ministerio de Economía, Industria y Competitividad (CGL2017-89063-P, CGL2017-83103-P), by a predoctoral fellowship from MCI to CRC, by Junta para Ampliación de Estudios programme to MRR, and by Juan de la Cierva and Ramón y Cajal programmes to GT., Peer reviewed

It contains data collected in Guadix, Granada (southeast Spain) in 2019, in the framework of a research to evaluate the effects of chemical and auditory cues of hoopoes (Upupa epops) in repellence and attraction of blood-feeding flies. Dataset includes number of mosquitoes, blackflies and biting midges collected in insect traps in the field in four habitat types and two sampling periods, in relation to different chemical and auditory stimuli derived from nestlings of this bird species., Financial support was provided by grants from the Spanish Ministerio de Economía, Industria y Competitividad (CGL2017-89063-P, CGL2017-83103-P). GT was also supported by the Ramón y Cajal Programme. We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI)., Peer reviewed

Data sampled in “Hoya de Guadix”, Granada, Spain, during breeding seasons (March-July) 2016 and 2019., Data file includes information about identity of each sampled starling nestling, the experiment and treatment assigned to them, biometric measurements on day 10 and day 14, and measurements of colour variables. Colour variables include colouration of eggshells (measured as Brightness and Blue-green chroma for eggs laid on the nest where each nestling was born (nest of origin), and the eggs laid on the nest where each nestling grew (nest of rearing)), and colouration of begging related traits (measured as Mean bright, Total hue, UV hue, Yellow-red hue, UV croma, Yellow-red chroma and Carotenoid chroma) for each body part (mouth, flanges and skin). The data set also includes the plasma carotenoid concentration of each sampled nestling., Ester Martínez Renau was financed by a predoctoral contract (PRE2018-085378), while the whole research group received funds from the Spanish Ministerio de Ciencia, Innovacion y Universidades, and European (FEDER) (CGL2017-83103-P)., Peer reviewed