Márton Herényi

Egg composition in relation to social environment and maternal physiological condition in the collared flycatcher

Offspring survival can be influenced by resources allocated to eggs, which in turn may be affected by the environmental factors the mother experiences during egg formation. In this study, we investigated whether experimentally elevated social interactions and number of neighbouring pairs influence yolk composition of collared flycatchers (Ficedula albicollis). Social challenge was simulated by presentation of a conspecific female. Experimental females spent more time near the cage and produced eggs with higher androgen concentration, but local breeding density did not affect yolk androgen level. Moreover, we found that females exposed to more intra-specific interactions and those that bred at higher density produced eggs with smaller yolk. These females may be more constrained in foraging time due to more frequent social encounters, and there might be increased competition for food at areas of higher density. In contrast, the present study did not reveal any evidence for the effect of social environment on yolk antioxidant and immunoglobulin levels. However, we found that yolk lutein and immunoglobulin concentrations were related to the female’s H/L ratio. Also, yolk lutein and α-tocopherol levels showed a seasonal increase and were positively related to the female’s plasma carotenoid level. Mothers may incur significant costs by transferring these compounds into the eggs, thus only females in good physiological condition and those that lay eggs later, when food is probably more abundant, could allocate higher amounts to the eggs without compromising their defence mechanisms. Our results suggest that environmental circumstances during egg formation can influence conditions for embryonic development.

Darker eggshell spotting indicates lower yolk antioxidant level and poorer female quality in the Eurasian Great Tit (Parus major)

ABSTRACT Protoporphyrin pigment causes the red-brown eggshell colors; however, for many species, the function of this pigment is unknown. It has been proposed that eggshell pigmentation may strengthen the shell or that it may be a sexually selected signal, which advertises the quality of the female and that of her offspring to the male parent. In this study, we aimed to discover whether protoporphyrin-based eggshell pigmentation patterns of Eurasian Great Tits (Parus major) were related to female or egg quality. Additionally, we tested whether different methods of eggshell pigmentation estimation could be reliable predictors of eggshell protoporphyrin levels. We found that spot intensity, spot size, spotting coverage, and brown spot chroma indicated the protoporphyrin pigment concentration of the eggshell. Our results revealed that Eurasian Great Tit females that laid eggs with darker pigmentation had more lymphocytes in their circulation and had paler yellow breast and lower UV plumage reflectance, possibly indicating poorer health and individual quality. However, we did not find evidence that eggshell pigmentation patterns indicated the body condition, body size, or plasma oxidative status of females. Furthermore, we found that eggs with darker spots contained lower concentrations of antioxidants in the yolk. High protoporphyrin levels may be detrimental to females as they may cause oxidative damage, and this may be why birds that laid eggs with darker spots deposited lower amounts of antioxidants into the egg yolk. Shell spot darkness may also indicate territory quality, as females that laid smaller clutches also laid eggs with higher eggshell pigmentation levels. Thus, our results suggest that shell spot darkness may indicate the state of health of the female, egg yolk antioxidant level, and possibly also the quality of the territory.

Effects of environmental conditions on the egg mass, yolk antioxidant level, eggshell thickness and eggshell spotting patterns of Great Tits (Parus major)

AbstractAvian mothers can influence the fitness of their offspring by resource investment into the egg. Allocation of macro- and micronutrients into the eggs may be costly for the female, therefore, we expect that resource investment may be affected by the environmental and social conditions the mother experiences during egg formation. Here, we investigated whether environmental circumstances experienced by the reproducing female exert an influence on egg mass, yolk antioxidant (lutein and tocopherol) concentration, eggshell thickness, and the eggshell spotting patterns of Great Tits (Parus major). Our study showed that when caterpillars were less abundant, in colder weather and when breeding in an area of higher local breeding density, female Great Tits laid eggs of lower mass, suggesting that adverse environmental circumstances constrain the macronutrient investment into the eggs. However, we found no evidence that yolk antioxidant concentration and eggshell thickness were affected by environmental factors. Female Great Tits may use their endogenous stores or spend more time and energy in finding sufficient amounts of dietary antioxidants and calcium under unfavourable environmental conditions, which may have a cost effect on their own conditions. We found that birds that bred in the beginning of the season laid eggs with darker eggshell spots. Moreover, females laid more spotted eggs in colder weather and when breeding in higher density areas. Our results suggest that Great Tits deposit more of the potentially harmful pro-oxidant protoporphyrin pigment into the eggshell under unfavourable environmental conditions.ZusammenfassungAuswirkungen von Umweltbedingungen auf Eimasse, Antioxidantiengehalt des Dotters, Schalendicke und Fleckung der Eischale bei Kohlmeisen (Parus major) Vogelmütter können die Fitness ihrer Nachkommenschaft durch die Ressourcen beeinflussen, die sie in ein Ei investieren. Die Abgabe von Makro- und Mikronährstoffen an die Eier kann für das Weibchen kostspielig sein, daher ist zu erwarten, dass die Investition von Ressourcen durch Umweltbedingungen und soziale Faktoren beeinflusst wird, denen die Mutter während der Eibildung ausgesetzt ist. Hier untersuchten wir, inwieweit die Umweltbedingungen, denen das Weibchen während der Fortpflanzung ausgesetzt war, einen Einfluss auf die Eimasse, die Konzentration von Antioxidantien (Lutein und Tocopherol) im Dotter, die Schalendicke und die Fleckung der Eischalen von Kohlmeisen (Parusmajor) ausübten. Unsere Studie zeigte, dass Kohlmeisen-Weibchen in Zeiten geringeren Raupenangebots, bei kälterem Wetter und in Brutgebieten mit höherer lokaler Brutdichte Eier von geringerer Masse legten, was darauf hindeutet, dass ungünstige Umweltbedingungen die Investition von Makronährstoffen in die Eier beschränken können. Allerdings fanden wir keine Hinweise darauf, dass die Konzentration von Antioxidantien im Dotter und die Schalendicke durch Umweltfaktoren beeinflusst wurden. Unter ungünstigen Umweltbedingungen können Kohlmeisen-Weibchen körpereigene Reserven angreifen oder mehr Zeit und Energie auf die Suche nach ausreichenden Mengen nahrungsgebundener Antioxidantien und Kalzium aufwenden, was zu Lasten ihrer eigenen Kondition gehen kann. Wir stellten fest, dass früh in der Saison brütende Vögel Eier mit dunklerer Schalenfleckung legten. Außerdem legten die Weibchen bei kälterem Wetter und in dichter besetzten Brutgebieten mehr gefleckte Eier. Unsere Ergebnisse deuten an, dass Kohlmeisen unter ungünstigen Umweltbedingungen mehr des potenziell schädlichen prooxidativen Pigments Protoporphyrin in der Eischale ablagern.

Integrated plumage colour variation in relation to body condition, reproductive investment and laying date in the collared flycatcher

The possible integration of different sexual ornaments into a composite system, and especially the information content of such ornament complexes, is poorly investigated. Many bird species display complex plumage coloration, but whether this represents one integrated or several independent sexual traits can be unclear. Collared flycatchers (Ficedula albicollis) display melanised and depigmented plumage areas, and the spectral features (brightness and UV chroma) of these are correlated with each other across the plumage. In a 5-year dataset of male and female plumage reflectance, we examined some of the potential information content of integrated, plumage-level colour attributes by estimating their relationships to previous and current year body condition, laying date and clutch size. Females were in better condition the year before they became darker pigmented, and males in better current year condition were also darker pigmented. Female pigment-based brightness was positively, while male structurally based brightness was negatively related to current laying date. Finally, the overall UV chroma of white plumage areas in males was positively associated with current clutch size. Our results show that higher degree of pigmentation is related to better condition, while the structural colour component is associated with some aspects of reproductive investment. These results highlight the possibility that correlated aspects of a multiple plumage ornamentation system may reflect together some aspects of individual quality, thereby functioning as a composite signal.

Breeding Experience and the Heritability of Female Mate Choice in Collared Flycatchers

Background Heritability in mate preferences is assumed by models of sexual selection, and preference evolution may contribute to adaptation to changing environments. However, mate preference is difficult to measure in natural populations as detailed data on mate availability and mate sampling are usually missing. Often the only available information is the ornamentation of the actual mate. The single long-term quantitative genetic study of a wild population found low heritability in female mate ornamentation in Swedish collared flycatchers. One potentially important cause of low heritability in mate ornamentation at the population level is reduced mate preference expression among inexperienced individuals. Methodology/Principal Findings Applying animal model analyses to 21 years of data from a Hungarian collared flycatcher population, we found that additive genetic variance was 50 percent and significant for ornament expression in males, but less than 5 percent and non-significant for mate ornamentation treated as a female trait. Female breeding experience predicted breeding date and clutch size, but mate ornamentation and its variance components were unrelated to experience. Although we detected significant area and year effects on mate ornamentation, more than 85 percent of variance in this trait remained unexplained. Moreover, the effects of area and year on mate ornamentation were also highly positively correlated between inexperienced and experienced females, thereby acting to remove difference between the two groups. Conclusions/Significance The low heritability of mate ornamentation was apparently not explained by the presence of inexperienced individuals. Our results further indicate that the expression of mate ornamentation is dominated by temporal and spatial constraints and unmeasured background factors. Future studies should reduce unexplained variance or use alternative measures of mate preference. The heritability of mate preference in the wild remains a principal but unresolved question in evolutionary ecology.

Laying date and polygyny as determinants of annual reproductive success in male collared flycatchers (Ficedula albicollis): a long-term study

Annual reproductive success (ARS) is one of the main components of lifetime reproductive success, a reliable measure of individual fitness. Previous studies often dealt with ARS and variables potentially affecting it. Among them, long-term studies that consider multiple factors at the same time are particularly important in understanding the adaptive value of different phenotypes. Here, we used an 18-year dataset to quantify the ARS of male collared flycatchers (Ficedula albicollis) on the basis of recruited offspring. We simultaneously assessed the effect of start of breeding, age, polygyny, body size and the expression of forehead patch (a sexually selected trait). The success of early breeding individuals was appreciably higher than late birds; however, breeding too early was also disadvantaged, and males that bred around the yearly median breeding date had the highest ARS. Polygynous males were more successful in years with good food supply, while in years with low food availability, they did not produce more recruits than monogamous males. The age of males, their forehead patch size and body size did not affect the number of recruits. Our findings support the importance of breeding date and suggest stabilizing selection on it in the long term. We also show that polygyny is not always advantageous for males, and its fitness pay-off may depend on environmental quality.

Unravelling the relationships between life history, behaviour and condition under the pace-of-life syndromes hypothesis using long-term data from a wild bird

The hypothesis of pace-of-life syndromes (POLS) predicts relationships between traits including life history traits and risk-taking behaviour that can be mediated by the trade-off between current and future reproductive value. However, alternative causal mechanisms may also generate covariance among these traits without trade-offs. We investigated the relationships between survival to the next year, current reproductive investment and risk-taking behaviour (flight initiation distance) in male collared flycatchers, Ficedula albicollis, using long-term data. We used structural equation modelling (SEM) to uncover whether the associations among traits are mediated by a common latent factor that determines how individuals balance the trade-off between current and future reproductive value. As trade-offs could be concealed when there are differences in resource acquisition between individuals, we also included potential causes of these differences, body mass and body size, in the analysis. We found that risk-taking behaviour was positively related to reproductive investment and negatively to survival to the next year as could be predicted if investment into a risky behaviour is traded against future prospects. However, the most supported SEM model also suggested that survival to the next year was positively related to current reproductive investment, contrary to predictions of a hypothesis based on trade-off. These results remained qualitatively similar when controlling for body condition. In conclusion, we only could derive partial support for the POLS hypothesis. We suggest that aspects of individual quality, and not only trade-offs, should also be considered when interpreting the relationships between life history and behavioural traits.Significance statementWe investigated the association between two life history components (survival to the next year and current reproductive effort) and risk-taking behaviour, relying on long-term records from a passerine bird, to investigate the predictions of the pace-of-life syndrome (POLS) hypothesis. Using structural equation modelling, we found support for a causal model that implies that risk-taking negatively affects survival to the next year and that survival to the next year and current reproductive effort are strongly and positively associated. Controlling for the effect of body condition did not fundamentally change these relationships. We could not find conclusive evidence for the investigated traits being mediated by a common underlying factor, as generally predicted by the POLS hypothesis. However, the sign of the relationship between risk-taking behaviour and survival to the next year was as predicted by the POLS hypothesis.

Winter body condition in the Collared Flycatcher: Determinants and carryover effects on future breeding parameters

ABSTRACT Factors that determine the condition of migratory birds at their wintering sites are poorly known. Age, sex, and morphological characteristics of birds may have an influence on their winter condition by affecting their foraging and competitive abilities. Winter body condition could have long-term consequences on the reproductive success of migratory birds during the subsequent breeding season. Using 3 yr of data from Collared Flycatchers (Ficedula albicollis), we examined the characteristics of winter-grown tail feathers, as indicators of winter body condition, in relation to sex, age, morphological traits, and future breeding variables. Tail feather mass was highly repeatable between years, but feather growth rate was not repeatable, which suggests that the latter trait mainly indicates environmental circumstances during molt, whereas feather mass may more strongly reflect genetic effects. Tail feathers of males and adults showed better quality than those of females and juveniles, possibly because of differences between age classes and sexes in individual quality and foraging skills or because of winter habitat segregation. Birds with longer wings produced better-quality tail feathers, which suggests that wing and tail feather characteristics are similarly affected, presumably by individual genetic quality. Smaller Collared Flycatchers grew their tail feathers faster during the winter molt, possibly because they had better foraging ability due to better flight maneuverability. Tail feather quality showed no relationship with laying date; however, females that had produced heavier tail feathers during winter laid larger clutches during the following breeding season, which suggests that tail feather mass potentially reflects intrinsic individual quality.

Sources of variation in haematocrit in the Collared Flycatcher (Ficedula albicollis)

Abstract The haematocrit rate of the blood shows the individual physiological state. As the haematocrit grows, the higher erythrocyte number results in more efficient oxygen uptake capacity which can lead to better performance and probably a better survival rate of an individual. Hence we assume that the high value of haematocrit reflects good health state. Altogether 308 blood samples were collected from a wild population of Collared Flycatchers (Ficedula albicollis) in two breeding stages during a period of 2008-2010. We tried to elucidate the relationship between condition and haematocrit level of an individual and studied the haematocrit changes of an individual between years. The haematocrit values differed between years. Females had higher haematocrit values than males in 2010 but not in 2009. At courtship the haematocrit level of males was higher, than during nestling care. The different environmental effects and energy demands of the individuals may be the driving force behind the observed changes in haematocrit level. Analysing the changes between two years, there was a positive correlation between changes in condition index and haematocrit of individuals. The haematocrit values of an individual were repeatable between years. This finding suggests that haematocrit can be informative about the individual’s general health state. Összefoglalás A vér hematokritértéke az egyed fi ziológiai állapotáról nyújt információt. Feltehetőleg a magas hematokritszint jó egészségi állapotot tükröz, mivel a vörösvérsejtek megemelkedett szintje nagyobb oxigénfelvételi kapacitást és hatékonyabb oxigénszállítást tesz lehetővé a szövetekhez, ami az egyed jobb teljesítőképességét eredményezi. A Pilis hegységben 2008 és 2010 között odútelepeken költő örvös légykapókon (Ficedula albicollis) vizsgáltuk a hematokritérték évek és ivarok közötti eltérését, majd hímek esetében az udvarlás és a fi ókanevelés stádiumában mért mintázatát. Vizsgáltuk az egyedek hematokritértékének és kondíciójának kapcsolatát. Továbbá számoltuk az egyedek hematokritértékének évek közötti repetabilitását. A hematokritértékek évek között több esetben eltértek. A hímek udvarlás alatti hematokritszintje magasabbnak bizonyult, mint fi ókanevelés alatt. Az egyedek hematokritértékének repetabilitása magas volt, évek közötti eltérése pedig pozitívan korrelált kondíciójuk változásával. Feltehetőleg az évek közötti varianciát az eltérő környezeti feltételek okozhatták, míg az udvarlás alatt mért magas hematokritszint a megelőző vonulás nagy energiaigényének következménye lehet. Bár a hematokritérték változása volt megfi gyelhető az évek és a szaporodási stádiumok között, az egyeden belül évek között mégis repetabilitást mutatott. Az egyedi hematokritértékek évek közötti repetabilitása lehetővé teszi, hogy a jelleg az egyed aktuális állapota mellett általános egészségi állapotáról is informáljon