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Mountain birds face numerous challenges caused by altitude‐dependent environmental seasonality. Although elevation gradients may affect bird morphology, migration strategy and/or phenology of seasonal events (breeding and moulting), the life histories of highland compared with lowland birds have been little explored. In this study we compared the growth rate and mass of the tail feathers of six forest passerine species sampled at different elevations in the Iberian Peninsula (north) and the Maghreb (south) to assess potential differences in moult duration and feather quality between highland and lowland bird populations. As timing is crucial in seasonal environments, we also explored seasonal changes in temperature in the different study areas as a proxy for the duration of the optimal temporal windows available in summer for breeding and moulting. In addition, we compared wing configuration between highland and lowland populations, which could reflect differences in their migration strategy (migratory versus sedentary). The results showed that highland birds had less time available for breeding and moulting, longer and more concave wings, and faster feather growth rates than lowland populations, but we found no consistent patterns of variation in feather mass. These results suggest that selection might have favoured an accelerated moult and a more migratory behaviour in highland populations to cope with the reduction in the optimal temporal window as elevation increases. These patterns are similar to those observed in migratory populations moving along latitudinal gradients to breed in highly seasonal northern environments. We therefore hypothesize that elevational gradients at the southern limit of the Palaearctic could be an important driving force promoting variation in feather growth rate and wing configuration, and probably also other avian life‐history characteristics. [ABSTRACT FROM AUTHOR]

Sylvicultural practices are increasingly directed at forest conservation, restoration and sustainable management. Forests with higher structural complexity are expected to be more resilient against climate change impacts and to have a higher diversity of ecological niches. The impact of forest structural complexity on individual organisms, however, is less well known. To bridge this knowledge gap, we here test if structurally more complex forests provide a more favourable nutritional environment for forests birds, using ptilochronology as an indicator for individual condition. We therefore measured the width of growth bars in tail feathers of great tits (Parus major) captured in 19 forest plots along a gradient of increasing structural complexity. After validating our assumption that series of growth bars reflect the outcome of an energetic income vs. expenditure balance with possible consequences for health and fitness, we show that birds in structurally more complex forests maintain a better nutritional status, probably due to a higher and more stable availability of food resources and more sheltered habitat. Dominant tree species, architecture and associated ecology also play an important role, as some of the observed relationships appear to be tree species-specific. Overall, we demonstrate the importance of a complex forest structure and herb layer, and argue for the need for individual research on the condition, performance and health of forest species to inform managers and policymakers on the impact of changing forestry practices on biodiversity and ecosystem functioning.

Feathers have a diversity of functions in birds and are costly to produce, so their growth rate and mass can be reliable indicators of nutritional condition at the time of production. Despite the potential for feather metrics to advance our understanding of foraging, they are underused in avian ecology. One reason for this is the difficulty of interpreting whether individual variation is driven by ontogenetic, genetic or environmental effects, which is exacerbated by the fact that most analyses have been done on cross‐sectional data. We addressed this deficit using a longitudinal dataset of tail feathers collected from great tits Parus major to test for ontogenetic and genetic effects on growth rate, mass and length, while controlling for body/feather size differences and other confounding factors. First, we found that the type of moult episode and experimentally‐induced replacement differentially affected the length, mass and growth of feathers, providing evidence of an ontogenetic effect that should be considered when comparing these feather traits across individuals as a measure of condition. Second, we detected moderate to high repeatability and heritability values from parent–offspring regression for these three feather traits, which are suggestive of an underlying genetic component of variation. Third, we used a mean centring within‐individual approach to test whether feather growth rate and feather mass (length‐corrected) are indeed positively correlated with each other as overlapping indicators of body condition in birds, and found that this association, although positive, is weak and only significant between individuals. This suggests that both metrics are not so intimately linked as originally thought, and probably have different sensitivities to variation in foraging performance and ecological conditions. Together with the higher plasticity of feather growth rate compared to feather mass, our results support the idea that feather growth rate is better suited for examining short‐term responses to environmental variation. [ABSTRACT FROM AUTHOR]

Feathers have a diversity of functions in birds and are costly to produce, so their growth rate and mass can be reliable indicators of nutritional condition at the time of production. Despite the potential for feather metrics to advance our understanding of foraging, they are underused in avian ecology. One reason for this is the difficulty of interpreting whether individual variation is driven by ontogenetic, genetic or environmental effects, which is exacerbated by the fact that most analyses have been done on cross‐sectional data. We addressed this deficit using a longitudinal dataset of tail feathers collected from great tits Parus major to test for ontogenetic and genetic effects on growth rate, mass and length, while controlling for body/feather size differences and other confounding factors. First, we found that the type of moult episode and experimentally‐induced replacement differentially affected the length, mass and growth of feathers, providing evidence of an ontogenetic effect that should be considered when comparing these feather traits across individuals as a measure of condition. Second, we detected moderate to high repeatability and heritability values from parent–offspring regression for these three feather traits, which are suggestive of an underlying genetic component of variation. Third, we used a mean centring within‐individual approach to test whether feather growth rate and feather mass (length‐corrected) are indeed positively correlated with each other as overlapping indicators of body condition in birds, and found that this association, although positive, is weak and only significant between individuals. This suggests that both metrics are not so intimately linked as originally thought, and probably have different sensitivities to variation in foraging performance and ecological conditions. Together with the higher plasticity of feather growth rate compared to feather mass, our results support the idea that feather growth rate is better suited for examining short‐term responses to environmental variation.

Tropical bird species are characterized by a comparatively slow pace of life, being predictably different from their temperate zone counterparts in their investments in growth, survival and reproduction. In birds, the development of functional plumage is often considered energetically demanding investment, with consequences on individual fitness and survival. However, current knowledge of interspecific variation in feather growth patterns is mostly based on species of the northern temperate zone. We evaluated patterns in tail feather growth rates (FGR) and feather quality (stress-induced fault bar occurrence; FBO), using 1518 individuals of 167 species and 39 passerine families inhabiting Afrotropical and northern temperate zones. We detected a clear difference in feather traits between species breeding in the temperate and tropical zones, with the latter having significantly slower FGR and three times higher FBO. Moreover, trans-Saharan latitudinal migrants resembled temperate zone residents in that they exhibited a comparatively fast FGR and low FBO, despite sharing moulting environments with tropical species. Our results reveal convergent latitudinal shifts in feather growth investments (latitudinal syndrome) across unrelated passerine families and underscore the importance of breeding latitude in determining cross-species variation in key avian life-history traits. [ABSTRACT FROM AUTHOR]

Moult of birds is shaped by environmental and genetic drivers whose relative contribution to the structure of feathers may differ within and between populations. In this study, we compare some traits of tail feathers (growth bars, mass, rachis width and barb length) between four populations of the Eurasian blackcap Sylvia atricapilla breeding at different elevations within the southwestern Palaearctic. We tested if these traits were related to the primary productivity of habitats (a surrogate of food availability) or were better explained as an adaptation to altitudinal movements. The distribution of primary productivity was positively related to blackcap abundance suggesting that the species tracked the most productive areas to breed. In this environmental setting, wing morphology (wing length, concavity and pointedness) suggested that lowland blackcaps were sedentary while blackcaps from highland areas were involved in altitudinal movements. The feathers of blackcaps inhabiting the highlands showed wider growth bars and rachis than those of the most productive lowland areas but did not differ in feather mass and barb length. Fast feather growth has been related to time constraints to moult and wider rachis to improve flight efficiency in migratory birds. Our results therefore suggest that differences in feather characteristics between southern populations of the Eurasian blackcap are better interpreted as an adaptive response to altitudinal migration than as a consequence of regional food availability. [ABSTRACT FROM AUTHOR]

Abstract In birds, concentrations of testosterone (T) and corticosterone (Cort) are closely connected with many morphological, behavioral, and other physiological traits, including reproduction, metabolism, immunity, and fitness. The direction of the effect of these hormones on above‐mentioned traits, and the potential feedback between hormones are in general unclear; in addition, knowledge on how age and sex can affect T and Cort concentrations is still inconsistent. Our study used a novel method to analyze testosterone and corticosterone in feathers (Tf, Cortf) based on the precolumn chemical derivatization of hormones before liquid chromatography–tandem mass spectrometry (LC‐MS/MS) analysis. Unlike previously used methods (RIA, EIA), our analytical procedure allows simultaneous analysis of both hormones from small amounts of feathers (4–25 mg) and, thus, overcomes the problem of insufficient detection limits. We applied this method to reveal associations between Tf and Cortf hormone concentrations and feather growth, age, and sex in feathers grown during the postbreeding (flanks) and prebreeding (tails) periods in barn swallows (Hirundo rustica). There was neither a correlation between prebreeding and postbreeding Tf, nor between prebreeding and postbreeding Cortf. Tail Cortf concentrations were negatively associated with tail feather growth rates. Feather hormone concentrations were correlated in the prebreeding period, negatively in males but positively in females. Both Cortf and Tf were higher in young birds compared to older ones, indicating either an age‐related decrease in hormone concentrations within individuals, or the selective disappearance of individuals with high steroid concentrations. Males and females did not differ in Cortf, but Tf concentrations were higher in males than females, particularly during the prebreeding period. In this study, we provide an effective method for analyzing hormones in feathers in an ecological context, especially in situations when the total amount of feathers available for the analysis is limited.

Forest fragmentation, a result of deforestation, not only decreases the amount of habitat available for wildlife, but also increases the isolation of the remaining fragments and the area of edges surrounding them. Also, deforestation often leads to the creation of a dynamic regenerating matrix where cleared land is subsequently abandoned. Here we examine the effects of fragmentation and landscape change on the nutritional condition of Amazonian rainforest birds at the Biological Dynamics of Forest Fragments Project, near Manaus, Brazil. We analyzed ptilochronology-based measurements of feather growth rate in 12 species living in fragments within a dynamic landscape over 21 years. Ptilochronology serves as an index of nutritional condition by revealing energy available for maintenance over 1–2 weeks while the feather is grown, allowing intraspecific comparison across treatments. Feather growth rate decreased in fragments surrounded by young second-growth borders but increased as fragment size and age of adjacent second-growth vegetation increased. Results from this simple, yet informative, measure of nutritional condition reveal physiological impacts of land cover change, including the response of birds to changes occurring at both local and landscape levels. Our results highlight the importance of looking beyond presence/absence data to describe fragmentation effects, and support the value of landscape-scale approaches for the conservation of tropical forest biodiversity.

Abstract Background Asymmetry in the wild is a controversial, and to date, unresolved subject. Fluctuating asymmetry (FA) is the developmental instability (intra-individual variation) while, directional asymmetry (DA) expresses the asymmetry of the population mean. Methods We analysed 63 Great Grey Shrike (Lanius excubitor) skins at the Naturalis Biodiversity Center, Leiden, the Netherlands. The black markings on the tails were digitized in order to evaluate the symmetry of the two sides of each shrike. Ptilochronology helped understand if nutritional condition affected symmetry. Results ANOVA revealed no significant differences in size of the tail between sexes (F = 1.67, p > 0.05). However, there was significant difference in the shape of the black area in feathers between the sexes (F = 2.14, p

Events during one stage of the annual cycle can reversibly affect an individual's condition and performance not only within that stage, but also in subsequent stages (i.e. reversible state effects). Despite strong conceptual links, however, few studies have been able to empirically link individual‐level reversible state effects with larger‐scale demographic processes.We studied both survival and potential reversible state effects in a long‐distance migratory shorebird, the Hudsonian Godwit Limosa haemastica. Specifically, we estimated period‐specific survival probabilities across the annual cycle and examined the extent to which an individual's body condition, foraging success and habitat quality during the nonbreeding season affected its subsequent survival and reproductive performance.Godwit survival rates were high throughout the annual cycle, but lowest during the breeding season, only slightly higher during southbound migration and highest during the stationary nonbreeding season. Our results indicate that overwintering godwits foraging in high‐quality habitats had comparably better nutritional status and pre‐migratory body condition, which in turn improved their return rates and the likelihood that their nests and chicks survived during the subsequent breeding season.Reversible state effects thus appeared to link events between nonbreeding and breeding seasons via an individual's condition, in turn affecting their survival and subsequent reproductive performance. Our study thus provides one of the few empirical demonstrations of theoretical predictions that reversible state effects have the potential to influence population dynamics. [ABSTRACT FROM AUTHOR]

Moulting and breeding are costly stages in the avian annual cycle and may impose trade-offs in energy allocation between both stages or in their timing. Here, we compared feather growth rates (FGR) of rectrices in adults between two pairs of small pelagic Procellariiformes species differing in moult-breeding strategies: the European storm-petrel Hydrobates pelagicus and Leach’s storm-petrel Oceanodroma leucorhoa breeding in the Northern Hemisphere (Faroe Islands), showing moult-breeding overlap in tail feathers; and the Wilson’s storm-petrel Oceanites oceanicus and black-bellied storm-petrel Fregetta tropica, breeding in the Southern Hemisphere (South Shetlands), temporally separating moult and breeding. We used ptilochronology (i.e., feather growth bar width) to reconstruct FGR reflecting relative energy availability during moult. Based on previous research, we expected positive correlations between feather length (FL) and FGR. Additionally, we expected to find differences in FGR relative to FL between the moult-breeding strategies, where a relatively higher FGR to FL indicates a higher energy availability for moult. To investigate if energy availability during moult in the studied species is similar to species from other avian orders, we used FGR and FL found in literature (n = 164) and this study. We fitted a phylogenetic generalized least squares (PGLS) model to FGR with FL, group (i.e., Procellariiformes vs. non-Procellariiformes) and the interaction FL * group as predictors. As it has been suggested that Procellariiformes may form two growth bars per 24 h, we fitted the same model but with doubled FGR for Procellariiformes (PGLSadj). The group term was significant in the PGLS model, but was not in the PGLSadj model, confirming this suggestion. Individually predicted FGR by the PGLSadj model based on FL, showed that the Southern species have a significantly higher FGR relative to FL compared to the Northern species. Additionally, we found no correlation between FL and FGR in the Northern species, and a positive correlation between FL and FGR in the Southern species, suggesting differences in the trade-off between feather growth and size between species from both hemispheres. The observed differences between the Northern and Southern species may be caused by different moult-breeding strategies. The Southern species may have had more energy available for moult as they are free from breeding duties during moult, while the Northern species may have had less free energy due to a trade-off in energy allocation between breeding and moulting. Our study shows how different moult-breeding strategies may affect relative nutritional condition or energy allocation during moult of migratory pelagic seabirds.

Shade coffee farming has been promoted as a means of combining sustainable coffee production and biodiversity conservation. Supporting this idea, similar levels of diversity and abundance of birds have been found in shade coffee and natural forests. However, diversity and abundance are not always good indicators of habitat quality because there may be a lag before population effects are observed following habitat conversion. Therefore, other indicators of habitat quality should be tested. In this paper, we investigate the use of two biomarkers: fluctuating asymmetry (FA) of tarsus length and rectrix mass, and feather growth bars (average growth bar width) to characterize the habitat quality of shade coffee and natural forests. We predicted higher FA and narrower feather growth bars in shade coffee forest versus natural forest, indicating higher quality in the latter. We measured and compared FA in tarsus length and rectrix mass and average growth bar width in more than 200 individuals of five bird species. The extent of FA in both tarsus length and rectrix mass was not different between the two forest types in any of the five species. Similarly, we found no difference in feather growth between shade coffee and natural forests for any species. Therefore, we conclude our comparison of biomarkers suggests that shade coffee farms and natural forests provide similar habitat quality for the five species we examined.

Moulting and breeding are costly stages in the avian annual cycle and may impose trade-offs in energy allocation between both stages or in their timing. Here, we compared feather growth rates (FGR) of rectrices in adults between two pairs of small pelagic Procellariiformes species differing in moult-breeding strategies: the European storm-petrel Hydrobates pelagicus and Leach’s storm-petrel Oceanodroma leucorhoa breeding in the Northern Hemisphere (Faroe Islands), showing moult-breeding overlap in tail feathers; and the Wilson’s storm-petrel Oceanites oceanicus and black-bellied storm-petrel Fregetta tropica, breeding in the Southern Hemisphere (South Shetlands), temporally separating moult and breeding. We used ptilochronology (i.e., feather growth bar width) to reconstruct FGR reflecting relative energy availability during moult. Based on previous research, we expected positive correlations between feather length (FL) and FGR. Additionally, we expected to find differences in FGR relative to FL between the moult-breeding strategies, where a relatively higher FGR to FL indicates a higher energy availability for moult. To investigate if energy availability during moult in the studied species is similar to species from other avian orders, we used FGR and FL found in literature (n = 164) and this study. We fitted a phylogenetic generalized least squares (PGLS) model to FGR with FL, group (i.e., Procellariiformes vs. non-Procellariiformes) and the interaction FL * group as predictors. As it has been suggested that Procellariiformes may form two growth bars per 24 h, we fitted the same model but with doubled FGR for Procellariiformes (PGLSadj). The group term was significant in the PGLS model, but was not in the PGLSadj model, confirming this suggestion. Individually predicted FGR by the PGLSadj model based on FL, showed that the Southern species have a significantly higher FGR relative to FL compared to the Northern species. Additionally, we found no correlation between FL and FGR in the Northern species, and a positive correlation between FL and FGR in the Southern species, suggesting differences in the trade-off between feather growth and size between species from both hemispheres. The observed differences between the Northern and Southern species may be caused by different moult-breeding strategies. The Southern species may have had more energy available for moult as they are free from breeding duties during moult, while the Northern species may have had less free energy due to a trade-off in energy allocation between breeding and moulting. Our study shows how different moult-breeding strategies may affect relative nutritional condition or energy allocation during moult of migratory pelagic seabirds. [ABSTRACT FROM AUTHOR]

A non-invasive study of trace element accumulation in tail feathers of the Kentish plover (Charadrius alexandrinus) was performed along the coastline of the northern littoral strip of the Venice Lagoon, with the aim to verify whether contamination may be a factor affecting conservation status of Kentish plover populations. Body burdens in feathers of 11 trace elements including toxic metals/metalloids and essential elements (As, Cd, Co, Cr, Cu, Hg, Ni, Pb, Se, V, Zn) were quantified by ICP-MS, then concentrations were normalized to feather's age calculated using ptilochronology in order to obtain daily deposition rates. Mercury emerged as a major threat to the conservation of the species, since average feather concentration was clearly above the adverse-effect threshold associated with impairment in the reproductive success in a number of bird species. Also Cd and Se occurred at levels that may impact on the conservation status of the studied species at local scale, even if to a lesser extent than Hg. Gender-related differences in trace element accumulation emerged only for As, although for this element the risks associated to environmental exposure seem to be negligible. • Feather analysis allows identification of possible contaminants of concern. • Hg is a major threat for conservation of Kentish plover in Venice Lagoon. • Exposure to Cd and Se may be of concern for Kentish plover conservation. [ABSTRACT FROM AUTHOR]

Long-distance migration is energetically costly and often has a significant impact on bird health and condition. Therefore, understanding the health status of birds during long-distance migration is of ecological interest; however, obtaining invasive health measures is not always feasible or practical. Bird feathers can provide information about individual bird condition independent of invasive and expensive blood tests and have been used previously as indicators of condition, even long after the season of feather growth. Here, we investigated this question using 2 migratory songbirds in North America, Western Palm Warblers (Setophaga palmarum palmarum), which have conspicuous white patches on their tail feathers, and Gray Catbirds (Dumetella carolinensis), which have prominent daily growth bars on their tail feathers. Feathers were collected from birds captured on Jekyll Island, Georgia, during their fall migration. From the feathers we quantified the size of white patches on warbler rectrices and estimated growth bar length (as an index of feather growth rate) on catbird rectrices using image analysis. We also obtained 2 measures of bird health for each species: estimates of white blood cell abundance from blood smears (immune status) and size-corrected body mass (body condition). Analyses of feather traits and how they relate to bird health indicated that warblers (n = 42) with larger white patches had significantly higher body condition indices, although no association with white blood cell abundance, and catbirds (n = 27) with faster feather growth had significantly lower white blood cell abundance, but no association with body condition. Given the utility of these feather characteristics, our results suggest these metrics can be used to provide some insights into the biology of songbirds during one of the most critical portions of the annual cycle, migration. [ABSTRACT FROM AUTHOR]

In birds, concentrations of testosterone (T) and corticosterone (Cort) are closely connected with many morphological, behavioral, and other physiological traits, including reproduction, metabolism, immunity, and fitness. The direction of the effect of these hormones on above‐mentioned traits, and the potential feedback between hormones are in general unclear; in addition, knowledge on how age and sex can affect T and Cort concentrations is still inconsistent. Our study used a novel method to analyze testosterone and corticosterone in feathers (Tf, Cortf) based on the precolumn chemical derivatization of hormones before liquid chromatography–tandem mass spectrometry (LC‐MS/MS) analysis. Unlike previously used methods (RIA, EIA), our analytical procedure allows simultaneous analysis of both hormones from small amounts of feathers (4–25 mg) and, thus, overcomes the problem of insufficient detection limits. We applied this method to reveal associations between Tf and Cortf hormone concentrations and feather growth, age, and sex in feathers grown during the postbreeding (flanks) and prebreeding (tails) periods in barn swallows (Hirundo rustica). There was neither a correlation between prebreeding and postbreeding Tf, nor between prebreeding and postbreeding Cortf. Tail Cortf concentrations were negatively associated with tail feather growth rates. Feather hormone concentrations were correlated in the prebreeding period, negatively in males but positively in females. Both Cortf and Tf were higher in young birds compared to older ones, indicating either an age‐related decrease in hormone concentrations within individuals, or the selective disappearance of individuals with high steroid concentrations. Males and females did not differ in Cortf, but Tf concentrations were higher in males than females, particularly during the prebreeding period. In this study, we provide an effective method for analyzing hormones in feathers in an ecological context, especially in situations when the total amount of feathers available for the analysis is limited. [ABSTRACT FROM AUTHOR]

• Feather growth bars (ptilochronology) are a valid indicator of nutritional stress. • Strengthening forest structural complexity likely promotes bird nutritional condition. • Diverse herbal layer contributes to more stable food supply during feather moult. • Future research should prioritize individual-based studies on health and condition. Sylvicultural practices are increasingly directed at forest conservation, restoration and sustainable management. Forests with higher structural complexity are expected to be more resilient against climate change impacts and to have a higher diversity of ecological niches. The impact of forest structural complexity on individual organisms, however, is less well known. To bridge this knowledge gap, we here test if structurally more complex forests provide a more favourable nutritional environment for forests birds, using ptilochronology as an indicator for individual condition. We therefore measured the width of growth bars in tail feathers of great tits (Parus major) captured in 19 forest plots along a gradient of increasing structural complexity. After validating our assumption that series of growth bars reflect the outcome of an energetic income vs. expenditure balance with possible consequences for health and fitness, we show that birds in structurally more complex forests maintain a better nutritional status, probably due to a higher and more stable availability of food resources and more sheltered habitat. Dominant tree species, architecture and associated ecology also play an important role, as some of the observed relationships appear to be tree species-specific. Overall, we demonstrate the importance of a complex forest structure and herb layer, and argue for the need for individual research on the condition, performance and health of forest species to inform managers and policymakers on the impact of changing forestry practices on biodiversity and ecosystem functioning. [ABSTRACT FROM AUTHOR]

The pace of life history events varies with latitude in many taxa. In birds, especially, life history events tend to be protracted in the tropics. This pattern is likely the result of reduced seasonality in resources and changes in trade-offs associated with risk of mortality. In general, animals invest more in reproduction per attempt and less in adult survival at higher latitudes. Feather growth is a major investment that birds make in their own survival, but geographic patterns of feather growth have received very little study. Evidence from separate studies of molt timing in individual species suggests that high-latitude species complete molt faster than tropical birds. Within species, feathers that are grown more quickly tend to show lower structural integrity than feathers grown more slowly, but seasonality of resources may place temporal constraints on the pace of feather growth. I hypothesized that increased seasonality of resources or decreased investment in adult survival in relation to reproduction would result in an increase in feather growth rate with latitude within species of birds. I tested this hypothesis and alternatives using ptilochronology methods to measure the growth rates of rectrices from museum specimens of 4 species of broadly distributed, resident Neotropical birds across their ranges. I compared these feather growth rates to latitude, climatic suitability, bioclimatic variables, sex, and body mass between and among species. I found that feather growth rate consistently increased with latitude in all 4 species. My results confirmed previous findings that feather growth rate increases with mass in a nonlinear fashion among species; but I found no consistent relationship between body mass and feather growth rate within species. I discuss these results in the context of life history theory and propose 3 potential mechanistic explanations for the relationship between feather growth rate and latitude within species, as (1) a programmed response to increasingly seasonal resources, (2) a decreased investment in adult survival, or (3) fixed to some other factor that may vary with latitude, such as basal metabolic rate. [ABSTRACT FROM AUTHOR]

Background: Asymmetry in the wild is a controversial, and to date, unresolved subject. Fluctuating asymmetry (FA) is the developmental instability (intra-individual variation) while, directional asymmetry (DA) expresses the asymmetry of the population mean. Methods: We analysed 63 Great Grey Shrike (Lanius excubitor) skins at the Naturalis Biodiversity Center, Leiden, the Netherlands. The black markings on the tails were digitized in order to evaluate the symmetry of the two sides of each shrike. Ptilochronology helped understand if nutritional condition affected symmetry. Results: ANOVA revealed no significant differences in size of the tail between sexes (F = 1.67, p > 0.05). However, there was significant difference in the shape of the black area in feathers between the sexes (F = 2.14, p < 0.05), and males had more elongated and slender black areas. Further, DA was observed only in males, but FA was noted in both sexes. Spearman correlation showed no significant association between FA score and tail features in both the sexes. However, in females, we observed a negative significant correlation between the number of fault and growth bars. The shape of the black area in the tail displayed no statistically significant association with the tail features in both sexes although growth bars influenced tail shape more than the number of fault bars. Conclusions: We concluded that the characteristics discovered by us need to also be checked in the field and if they can be used to sex individuals. Also, chromatic manipulative studies are require to verify if DA influences sexual selection in the Great Grey Shrike. [ABSTRACT FROM AUTHOR]

The timing of major life-history events, such as migration and moult, is set by endogenous circadian and circannual clocks, that have been well characterized at the molecular level. Conversely, the genetic sources of variation in phenology and in other behavioral traits have been sparsely addressed. It has been proposed that inter-individual variability in the timing of seasonal events may arise from allelic polymorphism at phenological candidate genes involved in the signaling cascade of the endogenous clocks. In this study of a long-distance migratory passerine bird, the willow warbler Phylloscopus trochilus, we investigated whether allelic variation at 5 polymorphic loci of 4 candidate genes (Adcyap1, Clock, Creb1, and Npas2), predicted 2 major components of the annual schedule, namely timing of spring migration across the central Mediterranean sea and moult speed, the latter gauged from ptilochronological analyses of tail feathers moulted in the African winter quarters. We identified a novel Clock gene locus (Clock region 3) showing polyQ polymorphism, which was however not significantly associated with any phenotypic trait. Npas2 allele size predicted male (but not female) spring migration date, with males bearing longer alleles migrating significantly earlier than those bearing shorter alleles. Creb1 allele size significantly predicted male (but not female) moult speed, longer alleles being associated with faster moult. All other genotype-phenotype associations were statistically non-significant. These findings provide new evidence for a role of candidate genes in modulating the phenology of different circannual activities in long-distance migratory birds, and for the occurrence of sex-specific candidate gene effects. [ABSTRACT FROM AUTHOR]

There is increasing evidence of adaptive preferential investment during moult in those feather tracts that are more advantageous for fitness. In this study, we assessed whether, after the manual removal of two functionally different flight feathers (one primary and one rectrix), birds from two common passerine species (Eurasian Blackcap Sylvia atricapilla and European Robin Erithacus rubecula) favoured the regeneration of primary (supposedly the most functionally important feathers) over rectrix feathers. Our results did not show differences between replaced primary and rectrix feathers in their final length, but demonstrated that the gap left by the loss of the primary feather was filled earlier, suggesting that a rapid repair of the most essential feather tracts is also evolutionarily advantageous during the adventitious replacement of plumage. [ABSTRACT FROM AUTHOR]

In many bird species, yearling individuals are less colorful than older ones. However, the causal factors behind this difference of color are for the moment unknown. Here, we used ptilochronology in Great Tits Parus major to assess how nutritional conditions experienced by the same birds as yearling and adult are associated with this increase of coloration. Nutritional status was not different between yearling and adult individuals, suggesting that the increase in coloration with age is not due to an increase in foraging efficiency with age. Instead, our study implicates other behavioral and/or ecophysiological factors that drive yearling/adult differences in carotenoid ornamentation. [ABSTRACT FROM AUTHOR]

The article presents research which examined the influences of hatching on the nutritional conditions of buzzards. Topics covered include the challenges faced by the youngest nestling during asynchronous hatching as well as the dominance of altricial young buzzards that were hatched first in a clutch. Also mentioned is the use of the method ptilochronology to measure the light and dark bands on the vane.

Ptilochronology, the study of feather growth bars, has been used to assess nutritional condition, yet the implementation of this technique can be challenging. This study investigated how a magnification aid and level of experience with the technique affected the variability and accuracy of ptilochronology measurements. The average width of growth bars was significantly narrower when made with a magnifying visor as opposed to the unaided eye, suggesting that future ptilochronology studies should incorporate magnification. Measurements were also influenced by the measurer's level of experience, suggesting that a learning curve must be taken into account when analyzing ptilochronology results. [ABSTRACT FROM AUTHOR]

Regular replacement of flight feathers is one of the most time-consuming activities in the annual cycle of flying birds. In principle, birds can decrease the time required to renew feathers by increasing the rate at which individual feathers grow and by growing more feathers simultaneously. Using 52 comparisons of 43 species from 26 families of birds that maintain the ability to fly while molting, we show that the average number of primary feathers growing simultaneously explains 60.0% of the variation in mass-corrected molt duration, whereas feather growth rate explains only 4.4% of the variation in mass-corrected molt duration. The trend is even stronger when species that grow all their primaries simultaneously are included in the analysis. We suggest that the rate at which feather tissue is produced cannot increase without compromising feather quality because the size of the feather follicle constrains the speed at which feathers can be generated. Thus, birds that must molt rapidly to meet time constraints in their life cycle may be forced to reduce the time spent molting mostly by growing more feathers simultaneously. [ABSTRACT FROM AUTHOR]

In songbirds, the ability to learn and render the species-specific song is influenced by the development of both the song nuclei in the brain and the syrinx (bird's vocal apparatus) early in the bird's life. In black-capped chickadees (Poecille atricapillus), habitat quality is known to affect song structure, with birds in high-quality habitat (mature forest) having a higher song consistency than birds in low-quality habitat (young forest). Although this difference is suspected to stem from differences in development, the developmental status of juvenile birds in either habitat remains unexplored. In this study, we used ptilochronology and feather corticosterone to compare the conditional state of juvenile chickadees in young and mature forest during two distinct periods of song learning - the sensory phase, which occurs prior to settlement, and the sensorimotor phase, which occurs post-settlement. A sample of juvenile males was captured and euthanized several weeks prior to their first breeding season to compare the development of song center nuclei and syrinx in both habitats. The corticosterone levels of natally-grown feathers were greater among birds that settled in mature than young forests - as these feathers were grown pre-settlement, they reflect differences in physiology during the sensory phase. This difference in conditional state is reflected by differences in syrinx and song center nuclei development later during the sensorimotor phase - birds in young forest have smaller syrinx, and moderately-larger RA, than birds in mature forest. Those differences could be responsible for the difference in consistency in song structure observed across habitats. The difference in physiological state across habitats, combined with potential compounding effect of differences in winter resources between habitats, could influence the difference in syrinx and neural development seen in juvenile males during the early spring, and influence the male's ability to learn and render their species-specific song. [ABSTRACT FROM AUTHOR]

The article presents a study which examines the impact of sibling competition on the stress dependent of nutritional status in broods of Upland Buzzards (Buteo hemilasius). The study was conducted in two separate areas in Mongolia, in which the biometrics of the 52 nestlings inn 22 active nests were measured during the 2007 breeding season. The results of the study showed that the corticosterone (CORT) levels differed between the first-and second-hatched siblings of Upland Buzzards. The study also reveals the association of stress with sibling conflicts.

Carry-over effects take place when events occurring in one season influence individual performance in a subsequent season. Blood parasites (e.g. Plasmodium and Haemoproteus) have strong negative effects on the body condition of their hosts and could slow the rate of feather growth on the wintering grounds. In turn, these winter moult costs could reduce reproductive success in the following breeding season. In house martins Delichon urbica captured and studied at a breeding site in Europe, we used ptilochronology to measure growth rate of tail feathers moulted on the winter range in Africa, and assessed infection status of blood parasites transmitted on the wintering grounds. We found a negative association between haemosporidian parasite infection status and inferred growth rate of tail feathers. A low feather growth rate and blood parasite infections were related to a delay in laying date in their European breeding quarters. In addition, clutch size and the number of fledglings were negatively related to a delayed laying date and blood parasite infection. These results stress the importance of blood parasites and feather growth rate as potentially mechanisms driving carry-over effects to explain fitness differences in wild populations of migratory birds. [ABSTRACT FROM AUTHOR]

The article discusses the results of a study on the impact of the enactment of bovine spongiform encephalopathy (BSE)-related regulation on the availability of food for Eurasian Griffon scavengers. The regulation aims to reduce the number of carcass removal and incineration to prevent the emergence of BSE, which in turn resulted to a decrease in available food for scavengers. The study showed that the regulation reduced inter- and intra-specific competition and produced healthier fledglings in adult birds with a good nutritional condition breed.

The ecological conditions that a bird experiences during any stage of its life cycle may have consequences that become manifested at later life stages, and these 'carry-over effects' may be major components of variance in individual performance. Condition-dependent feather growth rate, as assessed by growth bars width (GBW), provides a unique, though largely under-exploited tool to investigate carry-over effects of ecological conditions and individual physiological state during molt. In this study of breeding barn swallows Hirundo rustica, which undergo a single complete annual molt of tail and wing feathers during wintering in sub-Saharan Africa, we first show that old (≥ 2 yr) females have larger GBW than old males and yearlings. GBW was smaller with larger infestations by common ectoparasites of barn swallows, independent of the swallows' age or sex, and larger GBW was associated with a higher index of body condition during the breeding season in males. Larger GBW predicted higher seasonal reproductive output of older males, but not reproductive output of younger males or females of any age class, with this higher reproductive output of older males mediated by higher offspring fledging success. However, no relationship with GBW was observed for seasonal reproductive output of males in the spring preceding the winter when the feathers were grown. Hence, this study suggests that the analysis of the rate of feathers growth ('ptilochronology') has a larger potential to serve as a powerful tool in the study of carry-over effects than has been appreciated to date. Specifically, the present results support the idea that conditions experienced during wintering in Africa and proximately reflected by GBW have carry-over effects on body condition and breeding success. These effects are sex and age specific, being more pronounced in older males, possibly as a consequence of differences in annual time routines and susceptibility to extrinsic factors among sex and age classes. [ABSTRACT FROM AUTHOR]

The article presents a study to determine the accuracy of the ptilochronology method for nestling eastern bluebirds. It provides an overview of ptilochronology which is a method to determine the nutritional state of a bird by measuring the width of feathers which could be a useful proxy for assessing habitat quality. Results suggest that the feathers of the nestlings undergo daily pulses of growth but ptilochronology may not be a reliable method to determine the growth rate of the feathers.

Mercury (Hg) depuration into growing feathers is a well-studied phenomenon in waterbirds. Although the kinetics of Hg excretion in relation to molt and diet has been studied extensively, the relationship between the individual nutritional condition of nestlings and dietary Hg accumulation has not been investigated. In the present study, a body-condition index (BCI) and nutritional condition index (NCI) for nestlings of two waterbird species occupying different trophic positions on the aquatic food web were determined and used to predict Hg accumulation through diet. Candidate models consisting of these indices and nestling age were compared using Akaike's information criterion corrected for small sample sizes. For both species, the top-performing model contained the sole parameter of nutritional condition index (NCI). The relationship between Hg and NCI was stronger in the species foraging higher on the trophic web, which experienced higher rates of Hg depuration into feathers. Models containing BCI could not be discounted (AICc < 2) for one of the species and the utility of this index is discussed. Environ. Toxicol. Chem. 2012; 31: 1143-1148. © 2012 SETAC [ABSTRACT FROM AUTHOR]

Abstract: Habitat fragmentation poses a major threat to animal species worldwide. However, a lack of accurate and easy-to-collect biomarkers can hamper the identification of populations vulnerable to fragmentation. Ptilochronology, the measurement of growth bar length from feathers, has been shown to respond to individual nutritional status and may thus serve as a useful biomarker of habitat fragmentation in birds. We examined the influence of habitat fragmentation on feather growth bar length in the free-living Eurasian treecreeper (Certhia familiaris), an area-sensitive old-growth forest passerine breeding in boreal forests under intense management. We found no clear indication that feather growth bar length was associated with habitat fragmentation. However in young treecreepers, high amount of edge and large number of patches tended to be related to shorter growth bar length. Our results thus provide no strong support for the utility of ptilochronology as an important biomarker of habitat fragmentation in this species. [Copyright &y& Elsevier]

Winter body condition may play important roles in the life history of migratory birds, but it is difficult to estimate. We used the growth rate of winter-grown tail feathers of Collared Flycatchers Ficedula albicollis as an indicator of winter body condition, comparing this trait between age classes and sexes and relating it to plumage ornamentation (forehead and wing patch sizes). Adults and males were in better nutritional condition during winter, as indicated by their faster tail feather growth rates, than were yearlings and females, respectively, which could indicate differences in individual quality and foraging ability with age, or age- and sex-related winter habitat segregation. However, feather growth rate was related neither to the size of the winter-grown forehead patch nor to the size of the summer-grown wing patch, suggesting weak condition-dependence for the winter-grown ornament and complex life-history consequences for the summer-grown ornament. [ABSTRACT FROM AUTHOR]

The phytohaemagglutinin (PHA) skin-swelling test is one of the most widely used methods for cell-mediated immunity measurement in immunoecology. Although several studies have investigated the condition-dependent traits associated with the magnitude of cutaneous inflammatory response to PHA, the results concerning signalling of the responsiveness through ornamental traits are still controversial. This is especially true for carotenoid-based feather ornamentation in birds. We therefore examined the linkage between several condition-dependent traits, including the red ornamental coloration of the plumage, and the magnitude of the PHA-induced immune response in scarlet rosefinch, Carpodacus erythrinus, males. Our results show two important aspects of the PHA-induced inflammation in this species. First, histological analysis showed that the swelling response was dependent on basophil activity. Second, the magnitude of the response (increase in patagium thickness) was associated with individual size, carotenoid-based ornamental coloration and a ptilochronological marker of feather growth at the time of moulting (mean growth bar width), thus mirroring the long-term quality of the individual. The positive linkage between the individual size or mean growth bar width and the PHA response suggests an association between the magnitude of the response and individual metabolic rate. However, as the magnitude of the response was also related negatively to ornament saturation and positively to ornament lightness, our results indicate stronger responsiveness in inferior males. Highly ornamented, healthier individuals recruited fewer basophils into the inflamed tissue causing less intense swelling. To our knowledge, this study is the first to show a negative association between carotenoid-based plumage coloration and the magnitude of the PHA-induced immune response. [Copyright &y& Elsevier]

Abstract: Small random deviations from left–right symmetry in bilateral traits, termed fluctuating asymmetry (FA), are theoretically predicted to increase with environmental stress and believed to constitute a potential biomarker in conservation. However, reported relationships between FA and stress are generally weak and variable among organisms, traits and stresses. Here we test if, and to what extent, FA increases with nutritional stress, estimated from independent feather growth measurements, in free-ranging house sparrows (Passer domesticus). Ptilochronological feather marks showed significant heterogeneity among study plots, indicating that house sparrow populations were exposed to variable levels of nutritional stress during development. However, individuals from more stressed populations did not show increased levels of fluctuating asymmetry in tarsus or rectrix length, nor was there evidence for significant between-trait concordance in FA at the individual or the population level. Lack of support for FA in tarsus and rectrix length as estimator of nutritional stress in house sparrows may indicate that developmental instability is insensitive to nutritional stress in this species, poorly reflected in patterns of fluctuating asymmetry due to ecological or statistical reasons, or highly context-specific. Such uncertainty continues to hamper the use of FA as a biomarker tool in conservation planning. [ABSTRACT FROM AUTHOR]

Abstract: Owing to the extensive development of road networks, millions of animals are killed annually. This impact on the natural environment has been questioned: is there a selection of victims in the car collisions? and do road-kills, as do predators, influence a population by eliminating individuals in poor condition? We compared road-killed individuals to those killed by predators in SE Poland in three bird species: Yellowhammer Emberiza citrinella, Barn Swallow Hirundo rustica, and Chaffinch Fringilla coelebs. We applied ptilochronology, in which the width of feather growth bars represents an individual’s relative nutritional condition. Our results show that the analyzed species were in significantly better body condition than those killed by raptors. Our study does not concur with previous studies which concluded that weaker individuals are more vulnerable on the road. Raptors select prey in poor condition, but road-killed individuals are in significantly better condition, so apparently road-kill results in the random elimination of healthy individuals. The conservation implications of this study are far-reaching; future road construction and safety regulations must take wildlife into consideration. If these human-created habitats are killing a significant proportion of the healthier part of natural populations in a non-selective manner, this could result in situations where fragmented populations could be driven to a critical stage, and/or the situation of declining or endangered populations worsened further. [Copyright &y& Elsevier]

In human-dominated landscapes (semi)natural habitats are typically embedded in tracts of unsuitable habitat. Under such conditions, habitat characteristics and grain size of the surrounding landscape may affect how much food, and at what cost, is available for sedentary species with low home-range plasticity. Here we combine behavioural radio-tracking, feather ptilochronology, and landscape analysis to test how nutritional condition varies with home range size in 13 house sparrow [ Passer domesticus (Linnaeus, 1758)] populations along an urban gradient. Urban individuals occupied smaller home ranges than conspecifics from rural areas, most distinctly if key cover was highly scattered. In urban plots, patch connectivity, home range sizes, and activity areas were positively correlated, indicating that individual ranging behaviour was related to the spatial distribution of suitable habitat. Urban House sparrows also showed the smallest feather growth bars, which were positively related to home range size at plot level. In contrast, growth bar widths and home range sizes were negatively related in rural populations, whereas in suburban populations, both variables varied independently. We conclude that individuals from progressively more built-up areas show a restricted ability to adjust their daily ranging behaviour to the scattered distribution of critical resources. This may complement other putative causes of the widespread population decline of urban house sparrows. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101, 41–50. [ABSTRACT FROM AUTHOR]

Condition, defined as the amount of ‘internal resources’ an individual can freely allocate, is often assumed to be environmentally determined and to reflect an individual’s health and nutritional status. However, an additive genetic component of condition is possible if it ‘captures’ the genetic variance of many underlying traits as many fitness-related traits appear to do. Yet, the heritability of condition can be low if selection has eroded much of its additive genetic variance, or if the environmental influences are strong. Here, we tested whether feather growth rate – presumably a condition-dependent trait – has a heritable component, and whether variation in feather growth rate is related to variation in fitness. To this end, we utilized data from a long-term population study of Siberian jays ( Perisoreus infaustus), and found that feather growth rate, measured as the width of feather growth bars (GB), differed between age-classes and sexes, but was only weakly related to variation in fitness as measured by annual and life-time reproductive success. As revealed by animal model analyses, GB width was significantly heritable ( h2 = 0.10 ± 0.05), showing that this measure of condition is not solely environmentally determined, but reflects at least partly inherited genetic differences among individuals. Consequently, variation in feather growth rates as assessed with ptilochronological methods can provide information about heritable genetic differences in condition. [ABSTRACT FROM AUTHOR]

The article presents a study on the use of ptilochronology in examining melanin- and carotenoid-based ornaments in the bird Great Tit Parus major. The methods used in the study involve photographing the breast of the bird in Czech Republic, and taking 10 to 15 feathers to obtain reliable values. Results showed that there is no relationship of growth bar width to the size of melanin ornament, and revealed a decline of growth rate of tail feathers as the carotenoid levels in the breast increased.

The article presents a study which evaluates the nutritional condition of Upland Buzzard (Buteo hemilasius) nestling in the Mongolian Grassland Steppe using the ptilochronology technique. It states that the study conducted a field work in two separate habitat areas with different densities of Brandt's vole. The average hatchling numbers, width of growth bars, and body weight were determined in the high-vole density area (HVDA) and non-vole density area (NVA). Results show that the broods in areas with abundant voles have better nutritional condition than those located in areas with scarce voles. The study also concludes that ptilochronology was proved to be an effective method.

Intraspecific latitudinal clines in the body size of terrestrial vertebrates, where members of the same species are larger at higher latitudes, are widely interpreted as evidence for natural selection and adaptation to local climate. These clines are predicted to shift in response to climate change. We used museum specimens to measure changes in the body size of eight passerine bird species from south-eastern Australia over approximately the last 100 years. Four species showed significant decreases in body size (1.8–3.6% of wing length) and a shift in latitudinal cline over that period, and a meta-analysis demonstrated a consistent trend across all eight species. Southern high-latitude populations now display the body sizes typical of more northern populations pre-1950, equivalent to a 7° shift in latitude. Using ptilochronology, we found no evidence that these morphological changes were a plastic response to changes in nutrition, a likely non-genetic mechanism for the pattern observed. Our results demonstrate a generalized response by eight avian species to some major environmental change over the last 100 years or so, probably global warming. [ABSTRACT FROM AUTHOR]

The article presents a study which examines the Blackcaps in a Mediterranean forest located at the southern edge of the Iberian Peninsula. Researchers evaluated intra-individual constancy in the length, mass, and growth rate of tail feathers between complete moults of 13 free-living individual Blackcaps Sylvia atricapillia. Researchers found out that plumage is regularly replaced over the lifetime of birds and variable conditions experienced during plumage development can affect feather growth rate. They concluded that the time to produce similar feathers increases with age.

Migratory birds have less time for moulting than sedentary birds, which may force them to produce their feathers faster at the expense of reducing feather quality. However, the effects of migration on the trade-off between moult speed and plumage quality remain to be studied in natural populations. We analysed the relationship between growth rate and quality of individual feathers, taking advantage of natural variation between migratory and sedentary populations of blackcaps Sylvia atricapilla. As predicted by life-history theory, individual blackcaps showed variable individual quality, which was revealed by positive correlations between feather growth rate and feather mass within populations. However, migrants grew up their feathers faster, producing lighter feathers than sedentary blackcaps. These results support the idea that feather growth rate and feather quality are traded against each other in blackcaps. Such a trade-off is apparently caused by different selection associated to migratory and sedentary life styles, which opens new insights into the diversification of moult patterns in birds. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 98–105. [ABSTRACT FROM AUTHOR]