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[Aim]: Oceanic islands have often been colonized by small groups of individuals dispersing from the nearest mainland, giving rise to insular populations characterized by locally adapted phenotypes and low genetic diversity. Alternatively, due to past geo‐climatic changes, the present‐day distribution of the species may not correspond to that found at the time of the original colonization so that the current mainland distribution may not include the original source area, leading to erroneous assumptions regarding colonization history. Here, we use patterns of genetic variation to evaluate alternative colonization scenarios of an insular passerine in the Canary Islands., [Location]: La Palma (Canary Islands), Northern Africa and the Iberian Peninsula., [Taxon]: Red‐billed chough (Pyrrhocorax pyrrhocorax)., [Methods]: We use phylogeographical and coalescent analyses of mitochondrial DNA sequences and 10 microsatellite loci, together with Bayesian demographic modelling, to determine whether choughs on the island of La Palma originate from (a) present‐day populations in Iberia, (b) present‐day populations in the mountains of inland Morocco or (c) former populations in coastal Morocco, where suitable habitat existed in the past., [Results]: Both the mitochondrial and nuclear datasets indicate that the chough population on La Palma is genetically well differentiated from those in Iberia and Morocco, and that La Palma choughs are more closely related to choughs in Iberia than to those in Morocco. Genetic diversity in La Palma is lower than that of mainland populations, but shows no evidence of past bottlenecks. The best supported demographic model to explain the origin of La Palma choughs that is congruent with both genetic datasets includes a ‘ghost’ population closely related to Iberia, from which the insular population diverged within the last 30,000 years., [Main conclusions]: Our results are most consistent with the existence of a former connection between La Palma and Iberia along the North African coast, when suitable habitat was found there. Subsequent desertification of these coastal areas led to local extinctions that restricted gene flow between Iberia and the islands, promoting genetic differentiation. Our results provide a counterintuitive solution to a biogeographical enigma, and could help resolve the colonization history of other systems with similarly complex climatic pasts., The study was funded by projects from the Junta de Comunidades de Castilla‐La Mancha (PPIC10‐0094‐3036), the Spanish Ministry of the Environment (082/2002) and the Ministry of Science and Education (BOS2003‐05066 and CGL2015‐66381‐P). F. M. was supported by a Juan de la Cierva postdoctoral fellowship from Spain's Ministry of Science and Innovation (FJCI‐2017‐32055) for part of this work.

Several studies have shown that melanin‐based traits play a crucial role in social contexts as they are associated with dominance, personality and social behaviour. However, most of these studies have focused on adults, and the role of these traits in juveniles remains scarcely explored. Here, we explore the association between two melanin‐based traits and nestling personality in Common Kestrels Falco tinnunculus. Our results show that female nestlings with blacker plumages displayed bolder personalities, providing evidence of sex‐dependent phenotypic integration of these two traits in males and females. We consider that this differential integration may arise from different selection pressures acting on males and females on plumage colouration during adulthood and that nestling colouration can act as a status signal within the juvenile age‐class., The study was financed by the Spanish Ministerio de Economía y Competitividad (Project: CGL2013-42451-P). DLI is supported by a postdoctoral contract of the REMEDINAL3-CM program of Comunidad Autónoma de Madrid (REF: S2013/MAE-2719)

Order of birth has profound consequences on offspring across taxa during development and can have effects on individuals later in life. In birds, differential maternal allocation and investment in their progeny lead to variance in the environmental conditions that offspring experience during growth within the brood. In particular, laying and hatching order have been proposed to influence individual quality during the growing period, but little is known about the fitness consequences that these two factors have for offspring from a lifetime perspective. We explored the effect of laying and hatching order on post‐fledgling survival (measured as recruitment probability) and lifetime reproductive success (LRS) in Common Kestrels Falco tinnunculus, using a long‐term and individual‐based dataset. First‐hatched chicks showed higher survival probability and LRS than their siblings. This effect was not due to body condition of the individuals at adulthood, the quality of their mates or the reproductive outcome compared with later‐hatched individuals. Instead, first‐hatched chicks had a higher recruitment probability. This could be explained by the higher body condition attained by first‐hatched chicks at the end of the nesting period, perhaps due to an enhanced competitive advantage for food over their siblings at the time of hatching. Laying order, in contrast to hatching order, appeared to have little or no effect on LRS. Our results suggest that hatching order within siblings predicts fitness, and that better early‐life conditions during growth experienced by first‐hatched chicks improve first survival and then recruitment, resulting in an enhanced LRS., This study was financed by the Spanish Ministerio de Economía y Competitividad (Projects: CGL2004‐04479/BOS; CGL2007‐61395/BOS; CGL2010‐15726/BOS; CGL2015‐70639‐P). Suggestions from R. Kimball and two anonymous referees greatly improved an early version of this paper. This study was conducted in accordance with all applicable laws and rules set forth by the Spanish Government and all licences granted by Junta de Castilla y León.

Sexual dimorphism (SD) has evolved in response to selection pressures that differ between sexes. Since such pressures change across an individual's life, SD may vary within age classes. Yet, little is known about how selection on early phenotypes may drive the final SD observed in adults. In many dimorphic species, juveniles resemble adult females rather than adult males, meaning that out of the selective pressures established by sexual selection feminized phenotypes may be adaptive. If true, fitness benefits of early female-like phenotypes may constrain the expression of male phenotypes in adulthood. Using the common kestrel Falco tinnunculus as a study model, we evaluated the fitness advantages of expressing more feminized phenotypes at youth. Although more similar to adult females than to adult males, common kestrel fledglings are still sexually dimorphic in size and coloration. Integrating morphological and chromatic variables, we analysed the phenotypic divergence between sexes as a measure of how much each individual looks like the sex to which it belongs (phenotypic sexual resemblance, PSR). We then tested the fitness benefits associated with PSR by means of the probability of recruitment in the population. We found a significant interaction between PSR and sex, showing that in both sexes more feminized phenotypes recruited more into the population than less feminized phenotypes. Moreover, males showed lower PSR than females and a higher proportion of incorrect sex classifications. These findings suggest that the mechanisms in males devoted to resembling female phenotypes in youth, due to a trend to increase fitness through more feminized phenotypes, may provide a mechanism to constrain the SD in adulthood., This study was financed by the Spanish Ministerio de Economíıa y Competitividad (Projects: CGL2004-04479/BOS, CGL2007-61395/BOS, CGL2010-15726/BOS).

Knowledge of the genetic basis of sexual ornaments is essential to understand their evolution through sexual selection. Although carotenoid-based ornaments have been instrumental in the study of sexual selection, given the inability of animals to synthesize carotenoids de novo, they are generally assumed to be influenced solely by environmental variation. However, very few studies have directly estimated the role of genes and the environment in shaping variation in carotenoid-based traits. Using long-term individual-based data, we here explore the evolutionary potential of a dynamic, carotenoid-based ornament (namely skin coloration), in male and female common kestrels. We first estimate the amount of genetic variation underlying variation in hue, chroma and brightness. After correcting for sex differences, the chroma of the orange-yellow eye ring coloration was significantly heritable (h2 ± SE = 0.40 ± 0.17), whereas neither hue (h2 = 0) nor brightness (h2 = 0.02) was heritable. Second, we estimate the strength and shape of selection acting upon chromatic (hue and chroma) and achromatic (brightness) variation and show positive and negative directional selection on female but not male chroma and hue, respectively, whereas brightness was unrelated to fitness in both sexes. This suggests that different components of carotenoid-based signals traits may show different evolutionary dynamics. Overall, we show that carotenoid-based coloration is a complex and multifaceted trait. If we are to gain a better understanding of the processes responsible for the generation and maintenance of variation in carotenoid-based coloration, these complexities need to be taken into account.

Adaptation to insular environments often arises from changes and innovations in feeding behaviour allowing expanded foraging habits and an increased niche breadth. These shifts and innovations have traditionally been thought to be related to community-wide processes, but could also be the direct result of environmental constraints determining the abundance, availability and suitability of a particular food providing specific nutrients for survival, growth and reproduction. The link between environmental constraints on nutrients and life-history of insular organisms can help in understanding the convergent set of adaptations sustaining the ‘island syndrome’. We tested whether a potential insular nutrient shortage can drive diet shifts, nutritional biochemistry and growth stress, thus contributing to the modulation of life-history traits in a large passerine bird, the red-billed chough (Pyrrhocorax pyrrhocorax). Results supported the insular nutritional challenge hypothesis, linked to an insular insect shortage. An insect shortage may in turn have determined the reduced consumption of this source of protein but increased consumption of other arthropods, and notably fruits, by insular nestlings and fully-grown individuals. Island birds showed comparatively low circulating levels of nutrients and metabolites associated with the consumption of protein-rich animal matter as opposed to carbohydrate-rich vegetal matter, as well as high growth stress reflected in poor feather quality. We propose that feeding shifts derived from an insular insect shortage may exert a strong influence on the allocation of limited time, energy and nutrients among competing functions associated with physiological changes and investment in reproduction and self-maintenance. Traits and patterns generally defining the insular syndrome could thus be linked to particular insular nutrient constraints forcing feeding shifts and nutritional challenges with physiological, demographic and life-history consequences.

BACKGROUND: Ecologically based rodent pest management using biological control has never been evaluated for vole plagues in Europe, although it has been successfully tested in other systems. The authors report on the first large-scale replicated experiment to study the usefulness of nest-box installation for increasing the breeding density of common kestrels (Falco tinnunculus) and barn owls (Tyto alba) as a potential biological control of common vole (Microtus arvalis) abundance in agricultural habitats in north-western Spain. RESULTS: The results show that: (1) population density of both predator species increased in response to both nest-site availability and vole density; (2) voles are a major prey for the common kestrels during the breeding period; (3) vole density during the increase phase of a population cycle may be reduced in crop fields near nest boxes. CONCLUSION: The installation of nest boxes provides nesting sites for barn owls and kestrels. Kestrel populations increased faster than in areas without artificial nests, and the common vole was one of their main prey during the breeding season. The results suggest that local (field) effects could be found in terms of reduced vole density. If so, this could be an environmentally friendly and cheap vole control technique to be considered on a larger scale. © 2012 Society of Chemical Industry

Summary 1. Knowledge of how pathogens activate different components of the immune system to combat infections in the wild is a first step towards building a more global picture of the role that immunocompetence plays in host-parasite evolution and host life history. Ecological immunology is currently situated in this first step due, in part, to the scarcity of simple techniques to reliably evaluate immunocompetence in the field. In fact, controversy remains as to whether parasites act as immuno-stimulators promoting immune responses or as immune-depressors via immune resource depletion. 2. In this study we manipulated parasite infection (Caryospora, Protozoa, Apicomplexa) and vaccinated captive Eurasian kestrels (Falco tinnunculus) to study potential immunological responses in different components of the immune system: circulating lymphocyte lineages (CD4, CD5 and CD8), counts of total lymphocytes and white blood cells (WBC) and plasma immunoglobulins (α-1, α-2, β-1, β-2 and δ). 3. We also evaluated the efficacy of the PHA-assay, a common test used in ecological immunology, to gain information about T-cell-mediated immune response. 4. Experimentally infected and vaccinated (inoculated with attenuated parasites) birds showed drastic increases in CD4 and CD5 lymphocyte lineages, but not in CD8s, nor in total counts of lymphocytes or WBCs and no significant variation was observed in plasma globulins and in inflammatory reaction to PHA as a consequence of infection. PHA assay values were not correlated with initial (before vaccination) or final (after vaccination) values or with the response (final – initial) of T-lymphocyte lineages. 5. Individuals with initially lower numbers of CD4 showed higher numbers (higher immune response) after vaccination. In the case of CD5s, initial and final numbers were positively correlated. 6. This study shows that parasites clearly provoke immune activity stimulation through proliferation of T-lymphocytes (CD4 and CD5) and also reveals that other commonly used measurements, considered to be related to T-cell-mediated immunity, such as single-time-point measurements (total lymphocyte and WBC counts) or PHA assays, have a questionable capacity to provide information about immunological capacity to combat pathogens.

Nest-site fidelity is a life-history trait of birds that may produce benefits in terms of fitness. We studied the relationship between breeding success and nest fidelity in the White Stork Ciconia ciconia. We also studied how other factors such as age, sex, habitat, colony size and productivity in previous breeding attempts might interfere with this relationship. Our results showed that pairs with higher fidelity rates also have lower failure rates, and that breeding failure and productivity in the previous season influenced the frequency of nest change in the following season. In addition, a curvilinear relationship was found between age and nest fidelity. These results suggest that age is a major factor related to nest fidelity and therefore individual experience could explain this behaviour in the White Stork. Changing the nest involves a reproductive cost for which nest fidelity can be considered as an adaptive strategy to increase fitness.

Summary 1 Offspring sex ratio may be an unpredictable component of life history that might select for behavioural plasticity in parental care. If the parents do not have such plasticity and the two sexes of offspring differ in size, individuals in a brood or litter biased towards the larger sex offspring may suffer from food shortage. Sibling sex ratio could also affect the young through asymmetric sex-related sibling competition. 2 We created single-sex broods of sexually size-dimorphic Eurasian kestrels (Falco tinnunculus L.) with mixed-sex control broods in order to test whether parents have behavioural plasticity to respond to the sex ratio of their brood and whether smaller male chicks suffer from reduced health status because their larger female siblings outrival them in sibling competition. The experiment was conducted during two years (2000 and 2001) that differed in the abundance of voles, the main natural prey of kestrels. 3 No obvious effects of the brood sex ratio manipulation on parental effort were detected, as there were no differences in prey delivery rate, biomass of prey brought to the nest, body mass or heterophile/lymphocyte ratio of the parents. 4 Female chicks in all-female broods had lower haematocrit levels than those in mixed-sex broods in a year of low vole abundance. As haematocrit is an index of nutritional condition and health state, this result indicates that in the year of low vole abundance the female chicks in all-female broods fledged in poorer condition than those in mixed-sex broods. 5 These results indicate that when the parents do not alter their level of parental effort in response to the sex ratio of their brood, the young in a brood biased towards the larger sex offspring can be reared successfully when food is abundant, while they may suffer under food shortage situations. 6 Kestrel chicks of both sexes had low haematocrit levels and T cell-mediated immune responses in the year of low vole abundance. This result indicates that poor health state at fledging may provide a causal link for low recruitment of kestrels hatched in years of low vole abundance.

When resources are limited, parents should decide the optimal number, size, and sex of progeny, and offspring should decide the optimal allocation of resources to different costly functions, such as growth and immunity. We manipulated clutch sizes of Eurasian kestrels by one egg to estimate possible cumulative effects of incubation and chick rearing costs on parental body condition, feeding effort, and offspring viability. No obvious effects of clutch size manipulations on feeding effort were found while feeding effort was adjusted to the original clutch size. Enlarged and control nests suffered from higher nestling mortality than reduced nests, and chicks of the enlarged group were in poorer body condition than chicks of the reduced group. Controlling for body mass, male chicks exhibited lower cell-mediated immunity assessed by a cutaneous hypersensitivity response than females, but only in treatments suffering from food restrictions, as indicated by chick starvation. These novel results reveal inter-sexual differences in physiological strategies in early life, suggesting sex-related differences in susceptibility to disease and consequently in survival prospects of offspring.

We analysed genetic relatedness through DNA-fingerprinting in 38 two-chick families of Chinstrap Penguins Pygoscelis antarctica in the Vapour Col colony on Deception Island, Antarctica. Band-sharing coefficients between males and chicks in their nests, females and chicks in their nests and brood mates were very close to 0.50 and were not significantly different. Presumably unrelated pair mates showed much lower band-sharing coefficients (0.12), which differed significantly from those between putative parents and their chicks and between presumed siblings. No case of extra-pair paternity was detected according to the presence of novel bands or to band-sharing coefficients. Monogamy in the study population is not only social but also genetic.