BUSCADOR RECOLECTA

Dataset of the scientific article “Food supplementation of parents before hatching of the young prolongs the nestling period in Pied Flycatchers Ficedula hypoleuca"., Grants PID2019-106032GB-I00 funded by MCIN/AEI/10.13039/501100011033., Peer reviewed

In bi-parental species, reproduction is not only a crucial life-history stage where individuals must take ftness-related decisions, but these decisions also need to be adjusted to the behavioural strategies of other individuals. Hence, communication is required, which could be facilitated by informative signals. Yet, these signalling traits might have (co-)evolved in multiple contexts, as various family members usually meet and interact during reproduction. In this study, we experimentally explored for the frst time whether a colourful plumage trait in adults acts as a signal that regulates multiple intra-family interactions in a bird species, the blue tit (Cyanistes caeruleus). We expected that an experimental reduction of adults’ UV/yellow refectance
(i.e. a reduction of apparent individual quality) should afect the behavioural strategies of all family members. We found evidence for this at least in adults, since the partners of UV-blocked individuals (either males or females) increased their parental investment — perhaps to compensate for the apparent lower condition of their mates. As the UV-blocked adult did not change its provisioning behaviour, the partner presumably responded to the manipulated signal and not to a behavioural change. However, the ofspring did not co-adjust their begging intensity to the experimental treatment. It is thus possible that they responded to overall parental care rather than the signal. These results suggest that UV/yellow colouration of adult blue tits may act as quality signal revealing the rearing capacity to mates., Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. Grants CGL2016-79390-P and PID2019-106032GB-I00 (to JM) funded by MCIN/AEI/ https://doi.org/ 10.13039/501100011033 and by “ERDF A way of making Europe”. JG-C was supported by Grant BES-2017-079750 and JM by a Ramón y Cajal contract RYC-2014-15145 funded by MCIN/AEI/ https://doi.org/
10.13039/501100011033 and “ESF Investing in your future”., Peer reviewed

Avian feathers need to be replaced periodically to fulfill their functions, with natural, social, and sexual selection presumably driving the evolution of molting strategies. In temperate birds, a common pattern is to molt feathers immediately after the breeding season, the pre- basic molt. However, some species undergo another molt in winter- spring, the pre-alternate molt. Using a sample of 188 European passerine species, Bayesian phylogenetic mixed models, and correlated evolution analyses, we tested whether the occurrence of the pre-alternate molt was positively associated with prox-ies for sexual selection (sexual selection hypothesis) and nonsexual social selection (social selection hypothesis), and with factors related to feather wear (feather wear hypothesis) and time constraints on the pre- basic molt (time constraints hypothesis). We found that the pre-alternate molt was more frequent in migratory and less gre-garious species inhabiting open/xeric habitats and feeding on the wing, and margin-ally more frequent in species with strong sexual selection and those showing a winter territorial behavior. Moreover, an increase in migratory behavior and sexual selection intensity preceded the acquisition of the pre-alternate molt. These results provide support for the feather wear hypothesis, partial support for the sexual selection and time constraints hypotheses, and no support for the social selection hypothesis.KEYWORDSbirds, feather wear, pre-alternate molt, sexual selection, social selection, time constraintsTAXONOMY CLASSIFICATIONBehavioural ecology; Evolutionary ecology; Life history ecology, European Regional Development Fund; Spanish Ministry of Economy and Competitiveness, Grant/Award Number: CGL2013-48193-C3-1-P, CGL2013-48193-C3-3-P, CGL2017-83103-P, CGL2017-83843-C2-1-P and RYC-2014-15145; Spanish Ministry of Science and Innovation, Grant/Award Number: PID2019-106032GB-I00, Peer reviewed

[EN] In many bird species, physical aggression between males become more frequent during the female’s fertile period, as female encounters with extra-pair males are more frequent and can entail paternity losses. Male aggressiveness during this stage has been proposed as crucial for ensuring male reproductive success. Thus, plumage ornaments could represent honest signals of individual quality that could reflect the aggressiveness of paired territorial males. Furthermore, male aggressiveness could be related to mate quality or defensive capacity. We quantified extra-pair paternity in the broods and investigated the association of male and female traits with the aggressive behaviour of territorial paired males in a Spanish population of Pied Flycatchers (Ficedula hypoleuca), where territorial intrusions were simulated during the female fertile period by placing a taxidermic male mount close to the nest. We predicted that (1) more aggressive males should better protect their mates from intruding males and thereby reduce their paternity losses, (2) males with larger white patches and higher UV reflectance of wing patches should respond more strongly to intrusions, and (3) that males should be more aggressive when mated with higher quality females. We found evidence that males that responded less intensely to a territorial intrusion suffered a higher paternity loss, which offers strong support to the basic tenet of the theory of territoriality as paternity defence. Moreover, both the level of male aggressiveness and control of the territory increased with male UV reflectance of wing patches. Finally, we found, contrary to our prediction, that males were less aggressive when mated with more ornamented females., [GER] Bei vielen Vogelarten nimmt die Häufigkeit physischer Aggression zwischen Männchen während der fertilen Phase der Weibchen zu, wenn Zusammentreffen der Weibchen mit fremden Männchen häufiger sind und zu Vaterschaftsverlusten führen können. Die Aggressivität der Männchen in diesem Stadium gilt als entscheidend für die Sicherung ihres Fortpflanzungserfolgs. Somit könnten Gefiederornamente ehrliche Signale individueller Qualität darstellen, welche die Aggressivität verpaarter Reviermännchen widerspiegeln. Außerdem könnte die männliche Aggressivität in Verbindung mit der Qualität der Partnerin oder den Verteidigungsfähigkeiten stehen. An einer spanischen Population von Trauerschnäppern Ficedula hypoleuca bestimmten wir den Anteil von Fremdvaterschaften an den Bruten und untersuchten den Zusammenhang männlicher und weiblicher Merkmale mit dem Aggressionsverhalten verpaarter Reviermännchen, indem wir während der fertilen Phase der Weibchen durch Platzieren eines präparierten Trauerschnäppermännchens in Nestnähe eine Übertretung der Reviergrenze simulierten. Wir sagten vorher, dass: 1) aggressivere Männchen ihre Partnerinnen besser vor Eindringlingen beschützen und so ihre Vaterschaftsverluste reduzieren; 2) Männchen mit größeren weißen Flecken und stärkerer UV-Reflexion der Flügelfelder stärker auf Eindringlinge reagieren und dass 3) mit Weibchen höherer Qualität verpaarte Männchen aggressiver sind. Wir fanden Belege dafür, dass Männchen, welche schwächer auf eine Überschreitung der Reviergrenze reagierten, höhere Vaterschaftsverluste zu tragen hatten, was eine klare Bestätigung der Grundsatzthese ist, dass Territorialität der Vaterschaftsverteidigung dient. Außerdem nahmen sowohl die männliche Aggressivität als auch die Kontrolle über das Revier in Abhängigkeit von der UV-Reflexion der Flügelfelder bei den Männchen zu. Zu guter Letzt stellte sich entgegen unserer Erwartungen heraus, dass Männchen weniger aggressiv waren, wenn sie mit stärker ornamentierten Weibchen verpaart waren., Open Access funding enabled and organized by Projekt DEAL. Grants IJC2018-035011-I (A.C.), PID2019-109303 GB-I00 (A.C.) and PID2019-106032 GB-I00 (J.M.) funded by MCIN/AEI., Peer reviewed

In many species, offspring display conspicuous coloration already early in life, even though they might be very vulnerable to predation at this stage. However, most attention has been drawn to the conspicuous plumage displayed by adult individuals in a sexual context, while other signaling functions have been explored much less. Here, we investigated whether the yellow breast plumage of blue tit (Cyanistes caeruleus) nestlings shows patterns of condition dependence and hence signals individual quality, as has been described for adult birds. During three consecutive breeding seasons, we, therefore, explored the association between nestling body mass and three color components of the yellow breast plumage (i.e., UV chroma, carotenoid chroma, and total brightness), considering both within and among nest effects. Variation in carotenoid chroma was not related to body mass. However, UV chroma and total brightness varied with body mass on an among-nest level, suggesting that they might signal aspects of genetic quality or parental rearing capacity. Interestingly, we also found a within-nest effect of body mass on total brightness, suggesting that this is a good candidate for a condition-dependent signal within the family. Thus, other family members could rely on brightness to adjust their behavioral strategies, such as feeding behavior in parents. Our study thus reveals that certain color components of the yellow breast plumage might signal different aspects of offspring quality, and they might have a correlated signaling value across life-history stages., The study was financed by the Ministerio de Economía y Competitividad MINECO, Spain (project grants CGL2016-79390-P and PID2019-106032GB-I00 to J. Morales) funded by MCIN/AEI/https://doi.org/10.13039/ 50110 0011033 and by “ERDF A way of making Europe.” JG-C was supported by Grant BES-2017-079750
and JM by a Ramón y Cajal contract RYC-2014-15145 funded by MCIN/AEI/https://doi.org/10.13039/ 50110 0011033 and “ESF Investing in your future.”, Peer reviewed

Social interactions facilitate information exchange for, among others, decision making and conflict resolution
in animal societies. A central component of social interactions is the expression of signals of quality, and the role of signals can be expected to become more relevant in densely populated environments, in which social interactions are more frequent and the degree of conflict is probably stronger. We tested this hypothesis using the family context to explore whether a signal of quality expressed by the offspring modulates intrafamily interactions and whether it plays a more prominent role when the social density is increased. To this aim, we experimentally blocked a signalling trait, the ultraviolet (UV)/ yellow reflectance of breast feathers and used brood size as a proxy of social density in a small passerine, the blue tit, Cyanistes caeruleus. We found that UV-blocked offspring were involved in fewer social interactions than control nestlings, suggesting that the expression of quality signals might affect the position within the family social network. Interestingly, this effect was independent of brood size. Moreover, we detected an overall preference to be in physical contact with nestmates of a different UV colour phenotype, which was stronger in small broods. Our results suggest that quality signals expressed by the offspring can influence the intrafamily social structure and that this effect is modulated by social density and, presumably, by the degree of conflict., This work was supported by PID2019-106032GB-I00 and CGL2016-79390-P grants (to J.M.) funded by
MCIN/AEI/ https://doi.org/10.13039/501100011033 and by ‘ERDF A way of making Europe’. J.G-C. was supported by Grant BES-2017-079750 and J.M. by a Ramón y Cajal contract RYC-2014-15145
funded by MCIN/AEI/ https://doi.org/10.13039/501100011033 and ‘ESF Investing in your future’., Peer reviewed

Parents might initially produce more offspring than they might be able to raise. However, when offspring demand exceeds their parents´ rearing capacity, parents might shift care towards the offspring which yield greater fitness returns to achieve their optimal brood size via brood reduction. Such favoritism could rely on offspring signaling traits if these inform parents about offspring quality and hence about the pay-offs of their investment. Here we investigated whether favoritism of blue tit (Cyanistes caeruleus) parents for an offspring signal (i.e., ultraviolet (UV) plumage coloration) varies with brood demand. To test this, we experimentally
blocked the UV reflectance of yellow breast feathers in half of the nestlings of each brood, and then we sequentially performed two opposing brood size manipulations to vary nestling demand below or above parental rearing capacity. In reduced broods, nestlings begged overall less intensely and gained more body mass, supporting that parental rearing capacities sufficed to satisfy brood demand. Moreover, in reduced broods, UV-blocked nestlings (i.e., low-quality offspring) were fed and prey-tested more often. Yet, they begged more than control nestlings, suggesting that they were perhaps treated differently by other family members
or which they may exploit parental preferences beyond actual need (at least in reduced nests). Parents flexibly shifted their feeding rate and favoritism in response to short-term changes in family size, as there was no parental preference for enlarged broods. Such flexible parental feeding rules may allow parents to gain the upper hand in parent-offspring conflict. However, we did not find evidence that parental favoritism facilitated brood reduction, at least in conditions where demand was temporally enhanced., Grant PID2019-106032GB-I00 (to JM) funded by MCIN/AEI/https://doi.org/10.13039/501100011033 and by “ERDF A way of making Europe.” JG-C was supported by Grant BES-2017-079750 and JM by a Ramón y Cajal contract RYC-2014-15145 funded by MCIN/AEI/ https://doi.org/10.13039/501100011033 and “ESF Investing in your future.”, Peer reviewed