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DNA sequences: RAD-seq GenBank accessions SRR17125662- SRR17125721, RRBS-seq GenBank accessions SRR17145241-SRR17145300; NCBI project PRJNA786007. Scripts: Github repository https://github.com/AudeCaizergues/Epigenetics_and_the_city.; International audience; Identifying the molecular mechanisms involved in rapid adaptation to novel environments and determining their predictability are central questions in evolutionary biology and pressing issues due to rapid global changes. Complementary to genetic responses to selection, faster epigenetic variations such as modifications of DNA methylation may play a substantial role in rapid adaptation. In the context of rampant urbanization, joint examinations of genomic and epigenomic mechanisms are still lacking. Here, we investigated genomic (SNP) and epigenomic (CpG methylation) responses to urban life in a passerine bird, the Great tit (Parus major). To test whether urban evolution is predictable (i.e. parallel) or involves mostly nonparallel molecular processes among cities, we analysed both SNP and CpG methylation variations across three distinct pairs of city and forest Great tit populations in Europe. Our analyses reveal a polygenic response to urban life, with both many genes putatively under weak divergent selection and multiple differentially methylated regions (DMRs) between forest and city great tits. DMRs mainly overlapped transcription start sites and promotor regions, suggesting their importance in modulating gene expression. Both genomic and epigenomic outliers were found in genomic regions enriched for genes with biological functions related to the nervous system, immunity, or behavioural, hormonal and stress responses. Interestingly, comparisons across the three pairs of city-forest populations suggested little parallelism in both genetic and epigenetic responses. Our results confirm, at both the genetic and epigenetic levels, hypotheses of polygenic and largely nonparallel mechanisms of rapid adaptation in novel environments such as urbanized areas.

The genetic structure of animal populations has considerable behavioural, ecological and evolutionary implications and may arise from various demographic traits. Here, we use observational field data and molecular genetics to determine the genetic structure of an invasive population of monk parakeets, Myiopsitta monachus, at a range of spatial scales, and investigate the demographic processes that generate the observed structure. Monk parakeets construct large nests that can house several pairs occupying separate chambers; these nests are often aggregated within nesting trees. We determined patterns of relatedness within compound nests, within nesting trees and between trees. Spatial autocorrelation analyses of pairwise genetic relatedness revealed fine-scale genetic structure with relatives of both sexes spatially clustered within, but not beyond, nesting trees. In addition, males were more related to males sharing their compound nests than to other males occupying the same nesting tree. By contrast, males and females within compound nests were not significantly more closely related than elsewhere in the same tree, and we found no evidence for inbreeding. Adults showed high breeding site fidelity between years despite considerable disturbance of nest sites. Natal dispersal was female-biased, but dispersal distances were relatively short with some natal philopatry observed in both sexes. Sibling coalitions, typically of males, were observed amongst both philopatric and dispersing birds. Our results show significant clustering of kin within compound nests and nesting trees resulting from limited and coordinated natal dispersal, with subsequent breeding site fidelity. The resulting genetic structure has implications for social behaviour in this unusual parrot species.

Rates of phenotypic change are greater in cities than in any other habitat. Consequently, urban habitats are an ideal experimental area to study contemporary evolution and adaptation. A key question related to phenotypic changes in urban animals relates to the patterns of gene flow between the city and the natural habitats surrounding cities, but the results obtained thus far have been contradictory. The aim of this study was to analyze genetic differentiation and patterns of gene flow and size variation in urban blue tits Cyanistes caeruleus in Barcelona city, using a panel of 26 microsatellites. We compared birds from one locality at the city center, one at the suburban area, and one in a nearby forest. We found a significant genetic differentiation between the populations, which has evolved over a period of about 35 generations (50 years), based on historical data. There was significant gene flow between all populations. There was no significant asymmetric gene flow between the forest and the other two populations, which is consistent with balanced gene flow and dispersal. City birds were smaller than individuals from the forest. Simulations showed that the selection required to achieve these phenotypic differences would have to be high, which in turn suggests that phenotype-dependent dispersal may be involved.

Identifying the environmental drivers of variation in fitness-related traits is a central objective in ecology and evolutionary biology. Temporal fluctuations of these environmental drivers are often synchronized at large spatial scales. Yet, whether synchronous environmental conditions can generate spatial synchrony in fitness-related trait values (i.e., correlated temporal trait fluctuations across populations) is poorly understood. Using data from long-term monitored populations of blue tits (Cyanistes caeruleus, n = 31), great tits (Parus major, n = 35), and pied flycatchers (Ficedula hypoleuca, n = 20) across Europe, we assessed the influence of two local climatic variables (mean temperature and mean precipitation in February–May) on spatial synchrony in three fitness-related traits: laying date, clutch size, and fledgling number. We found a high degree of spatial synchrony in laying date but a lower degree in clutch size and fledgling number for each species. Temperature strongly influenced spatial synchrony in laying date for resident blue tits and great tits but not for migratory pied flycatchers. This is a relevant finding in the context of environmental impacts on populations because spatial synchrony in fitness-related trait values among populations may influence fluctuations in vital rates or population abundances. If environmentally induced spatial synchrony in fitness-related traits increases the spatial synchrony in vital rates or population abundances, this will ultimately increase the risk of extinction for populations and species. Assessing how environmental conditions influence spatiotemporal variation in trait values improves our mechanistic understanding of environmental impacts on populations. birds, climate, clutch size, comparative analysis, fitness-related traits, fledgling number, phenology, spatial synchrony, timing of breeding, weather

The coping style of an individual in relation to potentially dangerous situations has been suggested to be inherited in a polygenic fashion, SERT being one of the candidate genes. In this study, we assessed in free-living great tits (Parus major) the association between SNP290 in the SERT promoter and three standard fear-related behaviors: the response of the birds to a black-and-white flag fixed to the top of the nest box, distress calling rate of the birds in the hand once captured and the hissing call of incubating females when approached by a predator. We found a strong association between SNP290 polymorphism and the three risk-taking behaviors, with birds with genotype CT entering the nest box with the flag faster and displaying more distress calls and fewer hissing calls. CT birds could therefore be described as more proactive than CC individuals. These results also suggest that hissing behavior should be regarded as a fear-induced shy behavior, and confirm that SERT has an important function in relation to risk aversion behaviors and coping style.

espanolUna de las principales acciones en el cuidado y limpieza del plumaje de las aves es el bano. Las aves pueden banarse en agua, nieve, polvo e incluso hormigas. Esta mas raramente descrito el bano con hojas, en el que las aves aprovechan las gotas de agua acumuladas en las hojas para banarse. Aqui describimos cuatro observaciones de cotorras de Kramer Psittacula krameri, realizadas en 2017 y 2021, en las que aprovechan las gotas de agua acumuladas en las hojas durante la lluvia para banarse. Durante los ultimos veinte anos hemos observado con mucha frecuencia a las cotorras de pecho gris Myiopsitta monachus banarse en los charcos, pero nunca las hemos visto banarse con hojas. Se sabe que la cotorra de Kramer es muy reacia a bajar al suelo, lo que contrasta con la cotorra de pecho gris que busca muy a menudo alimento en el mismo. Por lo tanto, interpretamos que este bano con hojas podria ser una estrategia antipredatoria de la cotorra de Kramer que le evitaria bajar al suelo. catalaUna de les principals accions en la cura i neteja del plomatge a les aus es el bany. Les aus poden banyar-se en aigua, neu, pols i fins i tot formigues. S’ha descrit mes rarament el bany amb fulles, en que les aus aprofiten les gotes d’aigua acumulades a les fulles per banyar-se. Aqui descrivim quatre observacions de cotorres de Kramer Psittacula krameri, fetes el 2017 i el 2021, en que aprofiten les gotes d’aigua acumulades a les fulles durant la pluja per banyar-se. Durant els darrers vint anys hem observat amb molta frequencia les cotorres de pit gris Myiopsitta monachus banyar-se en tolls, pero mai les hem vist banyar-se amb fulles. Se sap que la cotorra de Kramer es molt reticent a baixar a terra, cosa que contrasta amb la cotorra de pit gris que hi busca aliment molt sovint. Per tant, interpretem que aquest bany amb fulles podria ser una estrategia antipredatoria per part de la cotorra de Kramer amb la qual evitaria baixar a terra. EnglishBathing is one of the main actions birds perform as part of their preening. They may bathe in water, snow, dust, and even ants. Leaf bathing, where birds make use of water droplets on leaves to bathe, is less common. Here we describe four observations between 2017 and 2021 of ring-necked parakeets Psittacula krameri bathing on water droplets on leaves during rain.Over the past twenty years we have often seen monk parakeets Myiopsitta monachus bathing in puddles but never on leaves. The monk parakeet often forages on the ground, but ring-necked parakeets are reluctant to do so. We therefore interpret that the leaf bathing we observed in the ring-necked parakeet could be an anti-predatory strategy to avoid going down to the ground

Comparación de la dieta de los carboneros comunes en entornos urbanos y forestales en un hábitat mediterráneo El escaso éxito reproductor y la condición física deficiente de los pollos de paseriformes en entornos urbanos se han atribuido a la escasez de alimentos en estos ambientes y a la mala calidad de estos. No obstante, existen pocos datos detallados sobre las presas que los progenitores llevan a sus pollos en el hábitat urbano. En este estudio, empleamos videocámaras instaladas en cajas nido con objeto de comparar la dieta que los carboneros comunes, Parus major, del medio urbano y forestal proporcionan a sus pollos en una zona del Mediterráneo. Asimismo, analizamos el tamaño de la nidada y el éxito de los volantones. El éxito reproductor de los carboneros comunes del medio urbano fue inferior al de las aves forestales. Se observó que la tasa media de alimentación por hora y por nidada de los progenitores del medio urbano fue inferior a la de los progenitores del medio forestal. Entre las tres categorías de presas, el porcentaje de arañas no varió en función del hábitat. Sin embargo, el porcentaje de orugas que los progenitores de carbonero común llevaron a los nidos fue mayor en el bosque que en el hábitat urbano, mientras que el porcentaje de “otras” presas mostró la pauta inversa. En el hábitat urbano, la categoría “otras” presas estuvo principalmente compuesta por mariposas y avispas adultas. Nuestro artículo se suma a la opinión de que las tasas de alimentación bajas y la escasez de orugas en los entornos urbanos pueden ser los factores que limitan el crecimiento de los pollos de carbonero común en estas zonas.

Breeding parameters for Monk Parakeets Myiopsitta monachus nesting in Barcelona, Spain, were collected for 651 nests over five breeding seasons. This invasive population has a high reproductive cap...

Urbanisation is increasing worldwide, and there is now ample evidence of phenotypic changes in wild organisms in response to this novel environment. Yet, the genetic changes and genomic architecture underlying these adaptations are poorly understood. Here, we genotype 192 great tits (Parus major) from nine European cities, each paired with an adjacent rural site, to address this major knowledge gap in our understanding of wildlife urban adaptation. We find that a combination of polygenic allele frequency shifts and recurrent selective sweeps are associated with the adaptation of great tits to urban environments. While haplotypes under selection are rarely shared across urban populations, selective sweeps occur within the same genes, mostly linked to neural function and development. Collectively, we show that urban adaptation in a widespread songbird occurs through unique and shared selective sweeps in a core-set of behaviour-linked genes., The genetic architecture underlying rapid adaptive responses to novel environments are poorly understood. A study of great tits from nine European cities finds that urban adaptation in a widespread songbird occurred through unique and shared selective sweeps in a core-set of behaviour-linked genes.

While most of the knowledge on invasive species focuses on their impacts, little is known about their potential positive effects on other species. Invasive ecosystem engineers can disrupt recipient environments; however, they may also facilitate access to novel resources for native species. The monk parakeet (Myiopsitta monachus) is a worldwide invader and the only parrot that builds its own communal nests, which can be used by other species. However, the ecological effects of these interspecific interactions are barely known. We compared the role of the monk parakeet as a nest-site facilitator in different rural and urban areas, both invaded and native, across three continents and eight breeding seasons. A total of 2690 nests from 42 tenant species, mostly cavity-nesting birds, were recorded in 26% of 2595 monk parakeet nests. Rural and invaded areas showed the highest abundance and richness of tenant species. Multispecies communal nests triggered interspecific aggression between the monk parakeet host and its tenants, but also a cooperative defense against predators. Despite the positive effects for native species, monk parakeets also facilitate nesting opportunities to other non-native species and may also transmit diseases to tenants, highlighting the complexity of biotic interactions in biological invasions., This research was funded by Severo Ochoa Program (SVP-2014-068732), Action COST “ParrotNet” (ES1304), Loro Parque Fundación (PP-146-2018-1), and Ministry of Economy and Competitiveness, Spanish Research Council (CGL-2016-79568-C3-3-P).

The phenology of many species shows strong sensitivity to climate change; however, with few large scale intra-specific studies it is unclear how such sensitivity varies over a species’ range. We document large intra-specific variation in phenological sensitivity to temperature using laying date information from 67 populations of two European songbirds covering a large part of their breeding range. Populations inhabiting deciduous habitats showed stronger phenological sensitivity compared with those in evergreen and mixed habitats. Strikingly, however, the lowest sensitivity was seen in populations that had experienced the greatest change in climate. Therefore, we predict that the strongest phenological advancement will not occur in those populations with the highest sensitivity. Our results show that to effectively assess the impact of climate change on phenology across a species range it will be necessary to account for intra-specific variation in phenological sensitivity, climate change exposure, and the ecological characteristics of a population.

Aim: Nest building is widespread among animals. Nests may provide receptacles for eggs, developing offspring and the parents, and protect them from adverse environmental conditions. Nests may also indicate the quality of the territory and its owner and can be considered as an extended phenotype of its builder(s). Nests may, thus, function as a sexual and social signal. Here, we examined ecological and abiotic factors—temperature, nest predation and interspecific information utilization—shaping geographical variation in a specific nest structure—hair and feather cover of eggs—and its function as an extended phenotype before incubation in great (Parus major) and blue tits (Cyanistes caeruleus) across Europe. We also tested whether egg covering is associated with reproductive success of great tits. Location: Fourteen different study sites and 28 populations across Europe. Taxon: Parus major, Cyanistes caeruleus. Methods: We recorded clutch coverage estimates and collected egg covering nest material from the tit nests. We also measured nest specific breeding parameters and phenotypic measurements on adults. We tested whether mean spring temperatures, nest predation rates and flycatcher (Ficedula spp) densities in the study areas explain the large‐scale geographical variation of clutch coverage and reproductive success of tits. Results: The degree of egg coverage of great tits increased with lower mean spring temperature, higher nest predation rate and higher flycatcher density. We did not find egg covering of blue tits to be associated with any of the ecological or abiotic factors. Moreover, egg covering of great tits was not associated with reproductive success in our cross‐sectional data, yet a rigorous assessment of fitness effects would require long‐term data. Main conclusions: Our findings suggest that, in great tits, egg covering may simultaneously provide thermal insulation against cold temperatures during egg‐laying in spring and also represent a counter‐adaptation to reduce information parasitism by flycatchers and nest predation. Hence, geographical variation in interspecific interactions, and consequently in co‐evolutionary processes, may affect the evolution of nest characteristics besides environmental conditions.

Urbanisation is currently increasing worldwide, and there is now ample evidence of phenotypic changes in wild organisms in response to this novel environment, but the extent to which this adaptation is due to genetic changes is poorly understood. Current evidence for evolution is based on localised studies, and thus lacking replicability. Here, we genotyped great tits (Parus major) from nine cities across Europe, each paired with a rural site, and provide evidence of repeated polygenic responses to urban habitats. In addition, we show that selective sweeps occurred in response to urbanisation within the same genes across multiple cities. These genetic responses were mostly associated with genes related to neural function and development, demonstrating that genetic adaptation to urbanisation occurred around the same pathways in wildlife populations across a large geographical scale.

Alien mosquito and vertebrate host species may create novel epidemiological scenarios for the transmission of pathogens naturally circulating in the invaded area. The exotic Monk parakeet (Myiopsitta monachus) has established populations in Europe and is currently considered an invasive pest. Due to their high abundance in urban areas, Monk parakeets could be involved in the transmission of pathogens, potentially a ecting wildlife and livestock. To test this hypothesis, we determined the prevalence and diversity of three vector-borne parasites, namely Plasmodium, Haemoproteus and Leucocytozoon, in Monk parakeets from Barcelona. Many areas of southern Europe shelter high densities of the invasive Asian tiger mosquito Aedes albopictus, which in addition to native mosquito species could a ect the transmission of mosquito-borne parasites, such as avian Plasmodium. Thus, we also sampled mosquitoes in the area to trace their blood-feeding hosts and determine the presence of Plasmodium parasites. Monk parakeets were neither infected by Plasmodium nor by Haemoproteus parasites, and only five individuals (3.13%; n = 160) were infected by Leucocytozoon. Monk parakeets were bitten by Culiseta longiareolata and represented 9.5% of Culex pipiens blood meals. The invasive Ae. albopictus showed a clear anthropophilic feeding pattern, with humans dominating its diet. Three Plasmodium lineages were detected in pools of Cx pipiens. These results suggest that Plasmodium circulating in the area cannot develop in the invasive Monk parakeet, in spite of the relatively high fraction of native mosquito vectors feeding on this species in its invaded distribution range.

Food is a main limiting factor for most populations. As a consequence, knowledge about the diet of invasive alien species determines the design of control measures. The Monk and Rose-ringed parakeets are two typical species of successful invasive parrots that are highly appreciated by people. Although some observations suggest that Monk parakeets rely on a higher percentage of anthropogenic food than Rose-ringed parakeets, no detailed quantitative data is available. The aim of this study was to compare the diet of the two parakeets using stable isotope analysis (SIA). We performed SIA of carbon and nitrogen in feathers collected in Barcelona, Spain. We also measured isotopic ratios for potential food sources. We reconstructed the diet of parakeets using Bayesian mixing models. The two species differed in the isotopic signatures of their feathers for both d13C and d15N. Diet reconstruction showed that Monk parakeets feed mainly on anthropogenic food (41.7%), herbaceous plants (26.9%) and leaves/seeds (22.2%), while Rose-ringed parakeets feed mainly on flowers/fruits (44.1%), anthropogenic food provided in the trap located at the museum (32.4%) and leaves/seeds (23.1%). The more detailed information we can obtain from the diet of these species is useful to develop more effective control measures for their populations. The Monk parakeet may be more susceptible to control through education local residents, given the greater use of anthropogenic food in this species compared to Rose-ringed parakeet. Our conclusions also indicate that SIA is a powerful tool in providing crucial information about the diet and informing measures to control invasive species. Key words: diet, stable isotopes, invasive species, Myiopsitta monachus, Psittacula krameri

BACKGROUND: Nicarbazin is an anti-coccidial product sometimes used as a contraceptive to reduce the size of feral pigeon populations. However, its effectiveness in reducing pigeon population size in cities has generated some controversy. Here, we evaluate its effectiveness in Barcelona city. RESULTS: We set 23 feeding stations in which we provided nicarbazin and 10 feeding stations with a placebo (untreated corn). Censuses were carried out before and after one year of treatment, in radii of 200 m around each feeder. We additionally censused 28 circles of 200 m of radius distributed randomly 200 m away from the feeders and 28 circles distributed >500 m away from the feeders, which acted as controls. Population size across the whole city was also evaluated pre- and post-treatment. We found that feral pigeon density did not change after one year of treatment, either in the circles around feeding stations with nicarbazin or in the areas around control stations distributed at 200 and >500 m from the feeders. Population size in placebo circles rose after a year by 10%. The pigeon census for the whole city of Barcelona showed a 10% increase. CONCLUSION: Overall, our results indicate that the nicarbazin treatment had no effect on the feral pigeon population size, and we advise against its use as a pigeon control method, at least in large cities. Keywords: Feral pigeon, Columba livia; nicarbazin; contraceptives; population size control

The integration and synthesis of the data in different areas of science is drastically slowed and hindered by a lack of standards and networking programmes. Long-term studies of individually marked animals are not an exception. These studies are especially important as instrumental for understanding evolutionary and eco-logical processes in the wild. Furthermore, their number and global distribution provides a unique opportunity to assess the generality of patterns and to address broad-scale global issues (e.g. climate change)., To solve data integration issues and enable a new scale of ecological and evolution-ary research based on long-term studies of birds, we have created the SPI-Birds Network and Database (www.spibirds.org)—a large-scale initiative that connects data from, and researchers working on, studies of wild populations of individually recognizable (usually ringed) birds. Within year and a half since the establishment, SPI-Birds has recruited over 120 members, and currently hosts data on almost 1.5 million individual birds collected in 80 populations over 2,000 cumulative years, and counting., SPI-Birds acts as a data hub and a catalogue of studied populations. It prevents data loss, secures easy data finding, use and integration and thus facilitates collab-oration and synthesis. We provide community-derived data and meta-data stand-ards and improve data integrity guided by the principles of Findable, Accessible, Interoperable and Reusable (FAIR), and aligned with the existing metadata lan-guages (e.g. ecological meta-data language)., The encouraging community involvement stems from SPI-Bird's decentralized ap-proach: research groups retain full control over data use and their way of data management, while SPI-Birds creates tailored pipelines to convert each unique data format into a standard format. We outline the lessons learned, so that other communities (e.g. those working on other taxa) can adapt our successful model. Creating community-specific hubs (such as ours, COMADRE for animal demogra-phy, etc.) will aid much-needed large-scale ecological data integration., The SPI-Birds have been supported by an NWO personal grant (grant number 016.Veni.181.054) to A.C., and a Research Council of Norway grant: 223257 (SFF-III) and 267511 (EVOCLIM).

L-M.C. and P.d.V. acknowledge support from the European Research Council (ERC) (Grant 678140-FluctEvol). The Montpellier tit group acknowledges the long-term support of the Observatoire des Sciences de l’Univers – Obser-vatoire de REcherche Montpelliérain de l’Environnement (OSU-OREME). The bighorn, mountain goat, and eastern gray kangaroo studies were supported by Natural Sciences and Engineering Research Council (NSERC) of Canada. Recent data collection for Wytham has been provided by grants from Biotechnology and Biological Sciences Research Council (BB/L006081/1), ERC (AdG250164), and the UK Natural Environment Research Council (NERC) (NE/K006274/1, NE/S010335/1). The Columbian ground squirrel study was supported by the National Science Foundation (Grant DEB-0089473). Trait and fitness data for hihi were collected/managed by John Ewen under New Zealand Department of Conservation hihi management contracts and research permits AK/15073/RES, AK-24128-FAU, 36186-FAU, and 44300-FAU and with additional financial support via NERC UK, The Leverhulme Trust UK, Marsden Fund New Zealand, and the Hihi Conservation Charitable Trust. The data on reindeer were made available through the Reindeer husbandry in a Globalizing North Nordic Center of Excellence, and the crew at Kutuharju Experimental Reindeer Research Station in the Reindeer Herder’s Association are thanked for their valuable assistance and logistic support in data collection. The red deer, Silwood blue tit, and Soay sheep datasets were supported by UK NERC. Lundy sparrow data were supported by NERC, a Marie Skłodowska-Curie Action, and Volkswagenstiftung. The red squirrel project was funded by NSERC of Canada and the National Science Foundation. J.C.S. was supported by a grant from the Ministry of Economy and Competitivity, Spanish Research Council (CGL-2016-79568-C3-3-P). J.T., T.K., and M.G. were supported by the Research Council of Norway through its Centers for Excellence funding scheme, Project 223257. Research on fairy wrens has been supported by the Australian Research Council. The Northern wheatear and the flycatcher studies were supported by grants from the Swedish Research Council VR. Temporal variation in natural selection is predicted to strongly impact the evolution and demography of natural populations, with consequences for the rate of adaptation, evolution of plasticity, and extinction risk. Most of the theory underlying these predictions assumes a moving optimum phenotype, with predictions expressed in terms of the temporal variance and autocorrelation of this optimum. However, empirical studies seldom estimate patterns of fluctuations of an optimum phenotype, precluding further progress in connecting theory with observations. To bridge this gap, we assess the evidence for temporal variation in selection on breeding date by modeling a fitness function with a fluctuating optimum, across 39 populations of 21 wild animals, one of the largest compilations of long-term datasets with individual measurements of trait and fitness components. We find compelling evidence for fluctuations in the fitness function, causing temporal variation in the magnitude, but not the direction of selection. However, fluctuations of the optimum phenotype need not directly translate into variation in selection gradients, because their impact can be buffered by partial tracking of the optimum by the mean phenotype. Analyzing individuals that reproduce in consecutive years, we find that plastic changes track movements of the optimum phenotype across years, especially in bird species, reducing temporal variation in directional selection. This suggests that phenological plasticity has evolved to cope with fluctuations in the optimum, despite their currently modest contribution to variation in selection. Postprint

Bird plumage is often very colorful and can communicate the quality of the bearer to conspecifics. These plumage-based signals of quality are composed of multiple pigments (e.g., melanin and carotenoids). Therefore, sex and age classes, which often show marked differences in plumage coloration, may have different dietary needs for the different plumage components and this might promote preferences for different dietary niches at different molting stages. However, no study has addressed the role that changes in niche use play in the expression of multiple component plumage signals in birds. We used stable isotope analysis to test the hypothesis that niche use is related to age and sex and to differently cultured plumage patches, yellow carotenoid-based and black melanin-based, in great tits Parus major. We recorded high niche overlap between plumage patches, although δ15N was higher in black than yellow plumage. Niche overlap was relatively low for age classes and relatively high for sex classes, and age classes showed a contrasting pattern of niche overlap between carotenoid- and melanin-based plumages. Moreover, δ13C, but not δ15N, had a significant negative relationship with carotenoid-based plumage, which was only apparent in juveniles. Taken together, our results demonstrate that niche use had a moderate influence on plumage coloration characteristics of great tit individuals, mostly associated with δ13C rather than with δ15N and with age rather than with sex. Therefore, our study is significant because it confirms the relevance of niche use during ornament production in free-living birds.

The diet of wild animals has been studied using many different strategies, approaches and methods in recent decades. In this regard, stable isotopes analysis (SIA) is becoming a widespread tool, but no study has yet, to our knowledge, compared diet estimations from SIA with direct observations of the diet of passerine nestlings. Accordingly, our aim was to test the predictive power of SIA for this purpose and identify potential confounding factors such as habitat effects. To do this, we compared isotopic signatures of δ 13 C and δ 15 N in the feathers of great tit ( Parus major ) nestlings, and the corresponding estimates of their diet based on stable isotope mixing models, with prey proportions delivered by their parents obtained through video-recordings. Between-nest differences in isotopic signatures of δ 15 N were larger than within-nest differences. We found that δ 15 N signatures of nestling feathers correlated positively with the proportion of spiders and negatively with the proportion of caterpillars in the nestlings’ diet, the most important prey types. On the other hand, between-nest and within-nest differences in δ 13 C ratios were of similar magnitude and δ 13 C ratios correlated mainly with the proportion of trees surrounding nest-boxes that were Quercus spp. Estimates of diet composition based on mixing models correlated with the observed nestling diet, yet effect sizes were quite low. Although mixing models are commonly used to ascertain diets, our data show that they can provide valuable information on the relative intake of prey types from different trophic levels; but when complex dietary patterns are recorded (e.g. due to the confounding effects of habitat and/or temporal variation) it can be difficult to draw firm conclusions about diet composition.

Dozens of morphologically differentiated populations, subspecies and species of cross- bills (genus Loxia) exist. It has been suggested that this divergence is due to variation in the conifer cones that each population specialises upon, requiring a specific beak size to efficiently separate the cone scales. If so, apparent survival should depend on beak size. To test this hypothesis, we undertook multievent capture–recapture modelling for 6844 individuals monitored during 27 years in a Pyrenean common crossbill L. curvirostra population in a forest of mountain pine Pinus uncinata. Apparent survival was indeed related to beak width, resulting in stabilizing selection around an optimum that was close to the observed mean beak width, indicating that local crossbill beak morphology is adapted to the conifer they feed upon. Both natural selection (selective mortality) and selective emigration of maladapted individuals may explain our find- ings. As is often the case in capture–recapture analyses but rarely recognised, we could not formally decompose apparent survival into selective mortality versus selective per- manent emigration. Nonetheless, there are several indications that selective permanent emigration should not be fully excluded. First, natural selection by itself would have to be unusually strong compared to other empirical estimates to create the observed pat- tern of apparent survival. Second, the observed mean beak width was a bit lower than the estimated optimum beak width. This can be explained by immigration of crossbills with smaller beaks originating from southern populations, which may subsequently have left the study area permanently in response to low food intake. This is in line with a detected transient effect in the data, yet apparently little influx from crossbills from northern Europe. When permanent emigration is phenotypically selective this will have ecological and evolutionary consequences, so this possibility deserves more attention in general. (Less)

Invasive species can have wide-ranging negative impacts, and an understanding of the process and success of invasions can be vital to determine management strategies, mitigate impacts and predict range expansions of such species. Monk parakeets (Myiopsitta monachus) and ring-necked parakeets (Psittacula krameri) are both widespread invasive species, but there has been little research into the genetic and social structure of these two species despite the potential links with invasion success. The aim of this study was to isolate novel microsatellite loci from the monk parakeet and characterise them in both monk and ring-necked parakeets in order to facilitate future investigations into their behaviour and population ecology. Sex-typing markers were also tested in both species. Of the 20 microsatellite loci assessed in 24 unrelated monk parakeets, 16 successfully amplified and were polymorphic displaying between 2 and 14 alleles (mean = 8.06). Expected heterozygosity ranged from 0.43 to 0.93 and observed heterozygosity ranged from 0.23 to 0.96. Nine of the 20 loci also successfully amplified and were polymorphic in the ring-necked parakeet, displaying between 2 and 10 alleles. Suitable markers to sex both species and a Z-linked microsatellite locus were identified. A multiplex marker set was validated for monk parakeets. These novel microsatellite loci will facilitate fine and broad-scale population genetic analyses of these two widespread invasive species.

Parasite-mediated competition has been reported to be one of the most harmful, although overlooked, impacts that alien species have on native ecosystems. Monk parakeets Myiopsitta monachus are successful invaders in Europe, where they have been introduced from South America. Colonial nests of these parrots may also host other species, e.g. the rock pigeon Columba livia forma domestica. In this work, we analysed the ectoparasite composition of monk parakeets in Barcelona (Spain) and we evaluated their potential role as parasite-mediated competitors, by comparing their parasitic load with that of coexisting rock pigeons. Only two arthropod species were observed on monk parakeets, whereas four species were detected on pigeons. Parakeets were rarely infested by pigeon parasites (prevalence = 0.66%), whereas parakeet mites were recorded more often on pigeons (prevalence = 10.00%). The number of total parasites per bird increased with increasing densities of monk parakeets, both for pigeons and for parakeets. Therefore, overcrowding of birds due to the increasing population of monk parakeets in Barcelona may affect the health status of native pigeons, suggesting a potential role for parasite mediated competition by introduced parakeets. Furthermore, spill-over of alien mites (Ornithonyssus bursa) by monk parakeets to rock pigeons should be monitoring as it may affect human health., The present study was funded by CGL-2016-79568-C3-3-P research project to JCS from the Spanish Research Council (Ministry of Economics and Competiveness).

espanolLos analisis de isotopos estables se han venido utilizando de forma generalizada en los ultimos anos para inferir la dieta de numerosas especies. El metodo isotopico consiste en utilizar factores de discriminacion entre la dieta y los tejidos para cada tipo de presa y tejido de depredador, es decir, determinar la diferencia entre la composicion isotopica de los tejidos del depredador y la de las distintas presas que integran su dieta. Hay muy poca informacion sobre los valores de los factores de discriminacion entre la dieta y los tejidos relativa a los psitaciformes. La finalidad de este estudio fue evaluar los valores de los factores de discriminacion de los isotopos de carbono y nitrogeno de la cotorra argentina (Myiopsitta monachus) y la cotorra de Kramer (Psittacula krameri), que son dos especies exoticas invasivas motivo de preocupacion. Alimentamos a aves en cautividad de las dos especies de cotorra con una dieta exclusivamente a base de semillas de girasol para establecer los factores de discriminacion relativos a la sangre y las plumas. En la cotorra argentina (N = 9), los factores de discriminacion para la sangre fueron: Δδ13C 2,14 ‰ ± 0,90 y Δδ15N 3,21 ‰ ± 0,75 y para las plumas: Δδ13C 3,97 ‰ ± 0,90 y Δδ15N 3,67 ‰ ± 0,74. Los factores de discriminacion de la cotorra de Kramer (N = 9) para la sangre fueron: Δδ13C (‰) 2,58 ± 0,90 y Δδ15N (‰) 2,35 ± 0,78 y para las plumas: Δδ13C 3,64 ‰ ± 0,98 y Δδ15N 4,10 ‰ ± 1,84. Los valores de los factores de discriminacion entre la dieta y la sangre de la cotorra de Kramer fueron significativamente mas elevados que los de la cotorra argentina. Con respecto a las plumas, no se observaron diferencias entre las dos especies. Nuestros resultados proporcionan los primeros valores de los factores de discriminacion para la sangre y las plumas en cotorras, que son fundamentales para inferir la dieta de estas especies mediante el analisis de isotopos estables. EnglishStable isotope analyses (SIAs) have been widely used in recent years to infer the diet of many species. This isotopic approach requires using diet to tissue discrimination factors (DTDFs) for each prey type and predator tissue, i.e., to determine the difference between the isotopic composition of the predator tissues and the different prey that conform its diet. Information on DTDF values in Psittaciformes is scarce. The aim of this study was to assess DTDF values for the carbon and nitrogen isotopes of the monk parakeet (Myiopsitta monachus) and the ring–necked parakeet (Psittacula krameri), two invasive alien species of concern. We fed captive birds of the two parakeet species on a single–species diet based on sunflower seeds to establish the DTDFs for the blood and feathers. In the monk parakeet (N = 9) DTDFs were Δδ13C 2.14 ‰ ± 0.90 and Δδ15N 3.21 ‰ ± 0.75 for the blood, and Δδ13C 3.97 ‰ ± 0.90 and Δδ15N 3.67 ‰ ± 0.74 for the feathers. In the ring–necked parakeet (N = 9), the DTDFs were Δδ13C (‰) 2.58 ± 0.90 and Δδ15N (‰) 2.35 ± 0.78 for the blood, and Δδ13C 3.64 ‰ ± 0.98 and Δδ15N 4.10 ‰ ± 1.84 for the feathers. DTDF values for the ring–necked parakeet blood were significantly higher than those for the monk parakeet blood. No difference was found between the two species in the DTDF for feathers. Our findings provide the first values of DTDFs for blood and feathers in these parakeets, factors that are key to infer the diet of these species based on SIA.

Carotenoid-based ornaments have been proposed to signal the ability to find food. The good-parent hypothesis suggests that females may rely on these carotenoid-based traits to assess male parental quality. A key question is whether the quality of these ornaments correlates with their performance at the moment of breeding. In this study, we assessed the parental investment of Mediterranean Great Tits Parus major in the early morning as a function of several environmental factors and of parental ornamentation. We measured this by the time that parents started feeding their offspring at the start of the day. In the morning, parents need to rapidly respond to the food demands of their offspring, after a long night without food. An earlier start of provisioning could indicate higher parental investment (and/or greater foraging ability). Our data indicate that fathers that show higher hue in their carotenoid-based plumage — more greenish individuals — started feeding their offspring earlier, thereby expanding the time window in which they work, while females did not show a significant relationship between the onset of provisioning and ornamentation. Parents, particularly mothers, that started earlier, worked more intensely across the whole observation period. Furthermore, parents started earlier when they had larger broods. Finally, more ornamented parents worked at lower rates, while more ornamented mothers raised offspring that had better body condition, which is in line with the good parent hypothesis. Although our results indicate that more ornamented males start feeding their offspring earlier, overall we found mixed support for the hypothesis that carotenoid-based ornaments signal the parental quality of a mate.

Comparación de la composición y el tamaño de las presas que el carbonero común (Parus major) y el herrerillo común (Cyanistes caeruleus) aportan a sus pollos en un bosque mediterráneo mixto esclerófilo La división de los recursos es un aspecto esencial en ecología porque puede determinar hasta qué punto pueden coexistir especies parecidas en un mismo hábitat. El carbonero común y el herrerillo común son especies que se utilizan tradicionalmente como modelo en los estudios sobre competencia trófica. No obstante, la mayoría de los estudios sobre este tema se han llevado a cabo en localidades en las que las orugas son, con diferencia, la presa que más se aporta a los pollos. Sin embargo, en los bosques mixtos mediterráneos la abundancia de orugas es relativamente escasa y son las arañas el elemento fundamental de la alimentación del carbonero común, al menos para los pollos. El objetivo del presente artículo es estudiar el aporte de alimentos al nido para establecer el grado de solapamiento de la dieta entre estas dos especies de paros en un bosque mediterráneo. Nuestros resultados mostraron que la tasa de alimentación del herrerillo común es superior a la del carbonero común, probablemente para compensar el hecho de que las presas que el herrerillo lleva a los pollos son de menor tamaño. El herrerillo común aportó más arañas que el carbonero, pese a que el carbonero gris llevó presas de mayor tamaño y más cantidad de orugas. Ello se debe a que el carbonero común puede cazar presas más grandes que el herrerillo. El principal resultado de este estudio respalda la hipótesis de la división de recursos entre el carbonero común y el herrerillo común en un ecosistema forestal mediterráneo esclerófilo., Resource partitioning is a central issue in ecology because it can establish to which point similar species can coexist in the same habitat. Great tits and blue tits have beenclassical model species in studies of trophic competence. However, most studies on the topic have been conducted atlocalities where caterpillars are by far the most relevant prey brought to the nestlings. In Mediterranean mixed forests,nevertheless, the abundance of caterpillars is relatively low and it is spiders that play a key role in the diet of great tits,at least for nestlings. The aim of this paper was to study nest food provisioning to establish the degree of diet overlapof these two tit species in a Mediterranean forest. Our results showed that blue tit feeding rates were higher than thoseof great tits, probably to compensate for the smaller prey delivered to nestlings by blue tits. Blue tits brought morespiders than great tits, while grey tits brought larger prey and more caterpillars. This may be because larger great titscan prey upon larger prey items than blue tits. As a main result, this study supports the view of resource partitioningby great and blue tits in sclerophyllous Mediterranean forest ecosystem

Many species only show sexual dimorphism at the age of maturity, such that juveniles typically resemble females. Under these circumstances, estimating accurate age-specific demographic parameters is challenging. Here, we propose a multievent model parameterization able to estimate age-dependent survival using capture–recapture data with uncertainty in age and sex assignment of individuals. We illustrate this modeling approach with capture–recapture data from the ring-necked parakeet Psittacula krameri. We analyzed capture, recapture, and resighting data (439 recaptures/resightings) of 156 ring-necked parakeets tagged with neck collars in Barcelona city from 2003 to 2016 to estimate the juvenile and adult survival rate. Our models successfully estimated the survival probabilities of the different age classes considered. Survival probability was similar between adults (0.83, 95% CI = 0.77–0.87) and juveniles during their second (0.79, 95% CI = 0.58–0.87) and third winter (0.83, 95% CI = 0.65–0.88). The youngest juveniles (1st winter) showed a slightly lower survival (0.57, 95% CI = 0.37–0.79). Among adults, females showed a slightly higher survival than males (0.87, 95% CI = 0.78–0.93; and 0.80, 95% CI = 0.73–0.86, respectively). These high survival figures predict high population persistence in this species and urge management policies. The analysis also stresses the usefulness of multievent models to estimate juvenile survival when age cannot be fully ascertained., The present study was funded by CGL‐2016‐79568‐C3‐3‐P research project to JCS from the Spanish Research Council (Ministry of Economics and Competitiveness). ASA was supported by a postdoctoral contract cofunded by the Regional Government of the Balearic Islands and the European Social Fund (ref. PD/003/2016). Rings were provided by the Catalan Ringing Office (ICO). We also wish to acknowledge the support provided by COST European Cooperation in Science and Technology Actions ES1304 “ParrotNet” for the development of this manuscript.

Solapamiento de nichos isotópicos entre el ruiseñor del Japón, invasivo, y los posibles competidores nativos Analizamos el solapamiento de nichos entre el ruiseñor del Japón, Leiothrix lutea, que es un ave exótica invasiva en expansión, y el petirrojo europeo, Erithacus rubecula, y la curruca capirotada, Sylvia atricapilla, que son especies nativas parecidas que se suelen considerar competidores potenciales en los bosques mediterráneos. Analizamos la relación de isótopos (δ13C y δ15N) en las plumas de las aves capturadas en varios lugares dentro de la cordillera de Collserola (Barcelona, NE España) en los que la población de ruiseñor del Japón ha aumentado notablemente en el último decenio, y cuantificamos el solapamiento de nichos con nicheROVER. Los individuos de curruca presentaron la menor probabilidad de encontrarse en el nicho isotópico de las otras dos especies (alrededor del 60 %), mientras que el ruiseñor y el petirrojo mostraron una elevada probabilidad de compartir el mismo nicho isotópico (el 82 %). Nuestros resultados destacan que la competencia por los recursos puede ser elevada y que las especies comparten marcadas asimetrías de nichos, lo que puede tener consecuencias para la dinámica de comunidades a largo plazo., We analysed niche overlap between the red–billed leiothrix Leiothrix lutea, a spreading exotic invasive bird, and the European robin Erithacus rubecula and the blackcap Sylvia atricapilla, similar native species, which are commonly considered as potential competitors in Mediterranean forests. We analyzed stable isotope ratios (δ13C and δ15N) from feathers of birds sampled in several locations within the Collserola mountain range (Barcelona, NE Spain) where leiothrix have strongly increased their numbers in the last decade and quantified niche overlap with nicheROVER. Blackcap individuals showed the lowest probability to be found in the isotopic niche of the other two species (around 60 %), while leiothrix and robins showed a high probability to share the same isotopic niche (82 %). Our results stress that competition for resources is potentially high and the species shared marked niche asymmetries, which may have implications for community dynamics in the long term.

DNA methylation is one of the main epigenetic mechanisms that can regulate gene expression and is an important means for creating phenotypic variation. In the present study, we performed methylation profiling of 2 candidate genes for personality traits, namely DRD4 and SERT, in the great tit Parus major to ascertain whether personality traits and behavior within different habitats have evolved with the aid of epigenetic variation. We applied bisulphite PCR and strand-specific sequencing to determine the methylation profile of the CpG dinucleotides in the DRD4 and SERT promoters and also in the CpG island overlapping DRD4 exon 3. Furthermore, we performed pyrosequencing to quantify the total methylation levels at each CpG location. Our results indicated that methylation was ∼1–4% higher in urban than in forest birds, for all loci and tissues analyzed, suggesting that this epigenetic modification is influenced by environmental conditions. Screening of genomic DNA sequence revealed that the SERT promoter is CpG poor region. The methylation at a single CpG dinucleotide located 288 bp from the transcription start site was related to exploration score in urban birds. In addition, the genotypes of the SERT polymorphism SNP234 located within the minimal promoter were significantly correlated with novelty seeking behavior in captivity, with the allele increasing this behavior being more frequent in urban birds. As a conclusion, it seems that both genetic and methylation variability of the SERT gene have an important role in shaping personality traits in great tits, whereas genetic and methylation variation at the DRD4 gene is not strongly involved in behavior and personality traits., The present study was funded by research project CGL2012–38262 to JCS from the Ministry of Science and Innovation, Spanish Research Council. Birds were handled and kept in captivity with the permission of the Environment Department of the Generalitat de Catalunya (licenses number 2012-SF/518, 2013-SF/677 and 2014-SF/090).

Animals competing for resources follow a general rule for which prior residents usually win contests over intruders. This prior residence effect might arise because animals possess a genetically fixed convention so that ‘residents always win’ (i.e. an uncorrelated asymmetry), because residents have a higher resource holding power (RHP) than intruders or because residents have a higher motivation to defend territories (i.e. pay-off asymmetry). The discrimination between these different hypotheses, though, has proven to be difficult. Eurasian siskins (Spinus spinus) provide us with an adequate opportunity to test for the effect of RHP on the prior residence effect. Siskins show two different strategies while in the wintering grounds: residents remain for several weeks on a given location while transients continuously move and residents are dominant over transients. The black bib area of male siskins signals their RHP. In this study, we compared the black bib area of a large sample of male resident and transient siskins and we found no differences between the two subpopulations. Hence, residence status in this species is not related to black bib size, which is a good proxy for RHP. Our results support the view that asymmetries in RHP are not required to explain the prior residence effect. We discuss the important implications that it has on the evolution of partial migration.

8 p., figuras, tablas -- versión publicada -- Este es un artículo distribuido bajo los términos de la licencia: http://www.biologists.com/user-licence-1-1/, Epigenetic modifications can respond rapidly to environmental changes and can shape phenotypic variation in accordance with environmental stimuli. One of the most studied epigenetic marks is DNA methylation. In the present study, we used the methylation-sensitive amplified polymorphism (MSAP) technique to investigate the natural variation in DNA methylation within and among subspecies of the house sparrow, Passer domesticus. We focused on five subspecies from the Middle East because they show great variation in many ecological traits and because this region is the probable origin for the house sparrow's commensal relationship with humans. We analysed house sparrows from Spain as an outgroup. The level of variation in DNA methylation was similar among the five house sparrow subspecies from the Middle East despite high phenotypic and environmental variation, but the non-commensal subspecies was differentiated from the other four (commensal) Middle Eastern subspecies. Further, the European subspecies was differentiated from all other subspecies in DNA methylation. Our results indicate that variation in DNA methylation does not strictly follow subspecies designations. We detected a correlation between methylation level and some morphological traits, such as standardized bill length, and we suggest that part of the high morphological variation in the native populations of the house sparrow is influenced by differentially methylated regions in specific loci throughout the genome. We also detected 10 differentially methylated loci among subspecies and three loci that differentiated between commensal or non-commensal status. Therefore, the MSAP technique detected larger scale differences among the European and non-commensal subspecies, but did not detect finer scale differences among the other Middle Eastern subspecies., This study was funded by research projects CGL-2012-38262 and CGL-2016-79568- C3-3-P (to J.C.S.) from the Ministerio de Economía , Industria y Competitividad

Aim: Effective policy and management responses to the multiple threats posed by invasive alien species (IAS) rely on the ability to assess their impacts before conclusive empirical evidence is available. A plethora of different IAS risk and/or impact assessment protocols have been proposed, but it remains unclear whether, how and why the outcomes of such assessment protocols may differ. Location: Europe. Methods: Here, we present an in-depth evaluation and informed assessment of the consistency of four prominent protocols for assessing IAS impacts (EICAT, GISS, Harmonia and NNRA), using two non-native parrots in Europe: the widespread ring-necked parakeet (Psittacula krameri) and the rapidly spreading monk parakeet (Myiopsitta monachus). Results: Our findings show that the procedures used to assess impacts may influence assessment outcomes. We find that robust IAS prioritization can be obtained by assessing species based on their most severe documented impacts, as all protocols yield consistent outcomes across impact categories. Additive impact scoring offers complementary, more subtle information that may be especially relevant for guiding management decisions regarding already established invasive alien species. Such management decisions will also strongly benefit from consensus approaches that reduce disagreement between experts, fostering the uptake of scientific advice into policy-making decisions. Main conclusions: Invasive alien species assessments should take advantage of the capacity of consensus assessments to consolidate discussion and agreement between experts. Our results suggest that decision-makers could use the assessment protocol most fit for their purpose, on the condition they apply a precautionary approach by considering the most severe impacts only. We also recommend that screening for high-impact IAS should be performed on a more robust basis than current ad hoc practices, at least using the easiest assessment protocols and reporting confidence scores., This study is a joint effort from a workshop organized under COST European Cooperation in Science and Technology Actions Parrotnet (ES1304) and Alien Challenge (TD1209). We would also like to thank two anonymous referees for helpful comments on an earlier version of this manuscript. D.S is currently funded by a Marie Skłodowska‐Curie Action under the Horizon 2020 call (H2020‐MSCA‐IF‐2015, grant number 706318) and acknowledges the Danish National Research Foundation for support to the Center for Macroecology, Evolution and Climate (grant number DNRF96). J.C.S. was supported by funds from the Ministry of Economy and Competitivity, Spanish Research Council (CGL‐2016‐79568‐C3‐3‐P).

Contour feathers cover most of the avian body and play critical roles in insulation, social communication, aerodynamics, and water repellency. Feather production is costly and the development of the optimum characteristics for each function may be constrained by limited resources or time, and possibly also lead to trade-offs among the different characteristics. Populations exposed to different environmental conditions may face different selective pressures, resulting in differences in feather structure and coloration, particularly in species with large geographical distributions. Three resident populations of great tit Parus major L. from different latitudes differed in feather structure and coloration. Individuals from the central population exhibited less dense and longer contour feathers, with a higher proportion of plumulaceous barbs than either northern or southern birds, which did not differ in their feather structure. Ultraviolet reflectance and brightness of the yellow of the contour feathers of the breast was higher for the southern than for the northern population. Birds with greener plumage (higher hue) had less dense but longer feathers, independently of the population of origin. Differences in feather structure across populations appear to be unrelated to the contour feather colour characteristics except for hue. Nutritional and time constraints during molt might explain the pattern of feather structure, whereas varying sexual selection pressure might underlie the coloration patterns observed. Our results suggest that different selective pressures or constraints shape contour feather traits in populations exposed to varying environmental conditions.(c) 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 114, 82-91. (Less)

Carotenoid-based coloration of nestling plumage is generally considered a reliable signal of quality and has consistently been related to habitat structure. The main hypothesis proposed to explain this correlation is that high quality habitats contain high quality food, which in return affects the expression of carotenoid-based plumage. It therefore assumes that, at the population level, the link between habitat structure and food composition is consistent and more relevant than inter-individual differences in foraging ability or parental investment. In addition, it is assumed by default that food and habitat produce concordant effects on nestling coloration. In this work we evaluated habitat structure and prey composition in addition to several measures of parental investment. We investigated their relative effect on carotenoid-based plumage coloration (lightness, chroma and hue) of great tit Parus major nestlings. We found a low correlation between carotenoid-based coloration of nestlings and that of their parents. Nestling coloration, especially lightness and chroma, increased with the intake of more spiders. The time of breeding was positively correlated with lightness and chroma and negatively correlated with hue. Finally, the maturity of oak trees surrounding nest-boxes correlated negatively with lightness, and the size of all tree species surrounding nest-boxes correlated positively with hue of chick plumage. Our findings support the view that habitat structure and prey composition may produce divergent effects on feather pigmentation, and that prey proportions and variables related to parental investment should be assessed when considering carotenoid-based coloration of chicks. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113, 547–555.

© 2014 The Authors. Nests are structures built to support and protect eggs and/or offspring from predators, parasites, and adverse weather conditions. Nests are mainly constructed prior to egg laying, meaning that parent birds must make decisions about nest site choice and nest building behavior before the start of egg-laying. Parent birds should be selected to choose nest sites and to build optimally sized nests, yet our current understanding of clutch size-nest size relationships is limited to small-scale studies performed over short time periods. Here, we quantified the relationship between clutch size and nest size, using an exhaustive database of 116 slope estimates based on 17,472 nests of 21 species of hole and non-hole-nesting birds. There was a significant, positive relationship between clutch size and the base area of the nest box or the nest, and this relationship did not differ significantly between open nesting and hole-nesting species. The slope of the relationship showed significant intraspecific and interspecific heterogeneity among four species of secondary hole-nesting species, but also among all 116 slope estimates. The estimated relationship between clutch size and nest box base area in study sites with more than a single size of nest box was not significantly different from the relationship using studies with only a single size of nest box. The slope of the relationship between clutch size and nest base area in different species of birds was significantly negatively related to minimum base area, and less so to maximum base area in a given study. These findings are consistent with the hypothesis that bird species have a general reaction norm reflecting the relationship between nest size and clutch size. Further, they suggest that scientists may influence the clutch size decisions of hole-nesting birds through the provisioning of nest boxes of varying sizes.

According to the “sexual selection hypothesis” (SSH), plumage conspicuousness has evolved through mate choice because it signals the quality of the bearer, and this is an honest signal because it involves a predation cost in terms of increased detectability to predators. Alternatively, according to the “unprofitable prey hypothesis” (UPH), conspicuousness is an aposematic signal indicating higher escape potential. We should expect the animals with higher predation risk (either conspicuous or dull, depending on the hypothesis) to have evolved antipredator behaviors to compensate for their higher predation risk (i.e. the “compensation hypothesis”). We tested these hypotheses by studying the vigilance behavior of wintering Eurasian Siskins (Spinus spinus) foraging on three feeders with different predation-risk and competition levels. Males were, on average, 50% more brightly colored than females. Males and females had similar wing loading, which allows us to reject male unprofitability related to hi...