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To perform their long-distance postnuptial migration, trans-Saharan migratory passerines must refuel repeatedly at different stopover sites. But some stopover sites have a specific role because most of the reserves needed to cross large ecological barriers (e.g., sea or desert) are stored there. This is the case in the west of the Iberian Peninsula, which is the main fattening area for European pied flycatcher Ficedula hypoleuca before they cross the Sahara. Upstream, no sites have been sampled in Western Europe between Great Britain and the southern Iberian Peninsula. Southwestern France is a main postnuptial route for this species with funnel effect between the end of the Pyrenees barrier and the Atlantic Ocean. In this area, we estimated energetic parameters from capture–mark–recapture data obtained during standardized monitoring. The mean stopover duration was relatively high, estimated at 8.4 days after the first capture by a capture–mark–recapture model and at 16.8 days assuming a similar duration before the first capture. Individual minimum stopover durations of 23 and 28 days were recorded. Pied flycatchers were fattening at an average rate of 0.29 g day−1 (3.1% of lean body mass) consistent throughout the season and independent of initial body mass, supporting the idea that the area was targeted for fattening. Very high fuel deposition rates over short durations were observed in several individuals (from 5 to 13.3% of their lean body mass). The mean fuel load did not differ by age or year and averaged 33.8% of lean body mass. The mean fuel load of the 25% heaviest fraction of birds was 57.3%, providing a flight range covering 80% of the distance to the southern margin of the Sahara. Hence, the departure fuel load was insufficient to cross the Sahara. At least one additional stopover would be necessary in the Iberian Peninsula, but for a moderate extra fuel. Individuals fattening under time pressure coexisted with individuals in prolonged stopover. Both behaviors are on few specific sites. Although the Sahara is still far away, South-West France is not solely a transit region concentrating birds because of the Pyrenees barrier. It must be an area of high refueling.

Long-term and short-term changes in ambient temperature can cause stress in birds, leading to changes in the level of hematological parameters. The H:L ratio (heterophil-to-lymphocyte ratio) is a hematological index that allows for the assessment of the stress induced by environmental changes, including weather conditions. In this paper, we examined the influence of temperatures and the sum of precipitation on the health of nestling pied flycatchers (Ficedula hypoleuca) by using the H:L ratio reflecting the body’s response to stress. All examined temperature indicators influenced the H:L ratio, yet the average value of daily minimum temperature during the first 12 days of nestling life had the strongest influence, maximum temperature had the weakest effect, while precipitation had no significant influence. Our research indicates that even a small increase in temperature caused a stress reaction in nestling pied flycatchers, which was reflected by an increase in the H:L ratio. The increase in the stress index (H:L ratio) was probably a result of poor weather conditions (precipitation, low temperature), which prevented the adult birds from actively foraging and properly feeding the nestlings.

Recently diverged taxa often exhibit heterogeneous landscapes of genomic differentiation, characterized by regions of elevated differentiation on an otherwise homogeneous background. While divergence peaks are generally interpreted as regions responsible for reproductive isolation, they can also arise due to background selection, selective sweeps unrelated to speciation, and variation in recombination and mutation rates. To investigate the association between patterns of recombination and landscapes of genomic differentiation during the early stages of speciation, we generated fine-scale recombination maps for six southern capuchino seedeaters (Sporophila) and two subspecies of White Wagtail (Motacilla alba), two recent avian radiations in which divergent selection on pigmentation genes has likely generated peaks of differentiation. We compared these recombination maps to those of Collared (Ficedula albicollis) and Pied Flycatchers (Ficedula hypoleuca), non-sister taxa characterized by moderate genomic divergence and a heterogenous landscape of genomic differentiation shaped in part by background selection. Although recombination landscapes were conserved within all three systems, we documented a weaker negative correlation between recombination rate and genomic differentiation in the recent radiations. All divergence peaks between capuchinos, wagtails, and flycatchers were located in regions with lower-than-average recombination rates, and most divergence peaks in capuchinos and flycatchers fell in regions of exceptionally reduced recombination. Thus, co-adapted allelic combinations in these regions may have been protected early in divergence, facilitating rapid diversification. Despite largely conserved recombination landscapes, divergence peaks are specific to each focal comparison in capuchinos, suggesting that regions of elevated differentiation have not been generated by variation in recombination rate alone.

The age-related variability of the frequency and structural–temporal parameters of the advertising song of Ficedula hypoleuca males in natural habitats and the urban environment were analysed. In the natural habitats, the range of male song frequencies, the maximal frequency, the number of figures, and the length of the song decreased from the third year of life. Similar age-related song changes in urban birds are observed earlier, from the second year of life. Urban birds have shown that the higher minimum song frequency increases with age, adapting the song to noise pollution.

Global warming affects breeding phenology of birds differentially with latitude, but there is contrasting evidence about how the changing climate influences the breeding of migrating songbirds at their northern breeding range. We investigate the effect of climate warming on breeding time and breeding success of European pied flycatchers Ficedula hypoleuca in Sweden during a period of 36 years using nest reports from bird ringing. To account for the latitudinal variation, we divided Sweden into three latitudinal bands (northern, intermediate, and southern). We applied a sliding window approach to find the most influential period and environment characteristics (temperature, vegetation greenness, and precipitation), using linear mixed models and model averaging. Our results show a long‐term advancement of breeding time related to increasing spring temperature and vegetation greenness during a period before hatching. Northern breeders revealed a larger advancement over the years (8.3 days) compared with southern breeders (3.6 days). We observed a relatively stronger effect of temperature and greenness on breeding time in the north. Furthermore, northern birds showed an increase in breeding success over time, while birds breeding at southern and intermediate latitudes showed reduced breeding success in years with higher prehatching temperatures. Our findings with stronger environment effects on breeding time advancement in the north suggest that pied flycatchers are more responsive to weather cues at higher latitudes. Breeding time adjustment and, potentially, low competition help explain the higher long‐term success observed in the north. Reduced breeding success at more southerly latitudes suggests an inability to match breeding time to very early and warm springs, a fate that with continued climate change could also be expected for pied flycatchers and other long‐distance migrants at their very northern breeding range., We investigate the effects of latitudinal variation of climate change on breeding time and reproductive success at the northern breeding range of a long‐distance migratory songbird. Birds breeding at the very north faced a stronger effect on breeding time advancement and their breeding success increased over the years, while more southerly breeding birds faced a lowered breeding success in very warm springs. Our results suggest that there is a risk that migratory birds will be more vulnerable to a continued climate change, especially in the north.

[EN] Sexually and socially selected signals are predicated to express the present and past condition of individuals and thereby their capacity to cope with environmental challenges. The concentration of corticosterone in feathers (CORTf) has been validated as a marker of activation of the hypothalamic-pituitary axis in birds during feather development. Measurements of CORTf can thus express the physiological stress of migratory birds during non-breeding periods of the annual cycle when feathers moulted in the wintering range are analysed. Thus, negative trends of ornament expression with CORTf may be predicted. Unpigmented plumage patches may constitute signals of phenotypic quality and are used in many species in social interac-tions by both sexes. Pied Flycatchers of both sexes Ficedula hypoleuca show white forehead and wing patches during the breeding season, of which the forehead and part of the wing patch (tertials) are moulted on the wintering grounds before spring migration. These patches are used as signals in social and sexual interactions and their expression has been previ-ously related to several indicators of physiological status. We collected tertials of females during nestling provisioning in a Spanish population and determined their CORTf in the laboratory. CORTf was thus measured in some of the prenuptially moulted feathers used as signals of social dominance by breeding females. According to AICc model selection, CORTf turned up in all the best models explaining forehead patch size and in most best models for wing patch size when controlling for age and size. Both forehead and wing patch sizes were negatively related to CORTf, although the trend for wing patch size was not significant. This indicates that breeding females expressing large unpigmented patches experienced low levels of stress during the prenuptial moult in their winter quarters, or that strongly signalling individuals present a lower level of activation of the HPA axis. [AL] Soziale und für das jeweilige Geschlecht selektierte Signale sollen die gegenwärtige und vorangegangene Verfassung von Individuen anzeigen und damit ihre Fähigkeit, mit den Herausforderungen der Umwelt fertigzuwerden. Die Konzentration von Kortikosteron in den Federn (CORTf) wurde bei Vögeln während der Federentwicklung als Marker für die Aktivierung der Hypothalamus-Hypophysen-Achse validiert. Messungen des CORTf können daher den physiologischen Stress von Zugvögeln im Jahreszyklus außerhalb der Brutzeiten ausdrücken, wenn man im Überwinterungsgebiet bei der Mauser aus-gefallene Federn analysiert. Somit können möglicherweise negative Trends im gesamten Federkleid vorhergesagt werden. Unpigmentierte Stellen im Gefieder können Signale der phänotypischen Qualität darstellen und werden bei vielen Arten in sozialen Interaktionen von beiden Geschlechtern verwendet. Trauerschnäpper (Fidecula hypoleuca) beider Geschlechter zeigen während der Brutzeit weiße Stirn- und Flügelflecken; die Federn an Stirn und Teilen der Flügel mausern im Win-terquartier vor Beginn des Frühjahrszuges. Die Flecken werden in sozialen Interaktionen und zwischen den Geschlechtern als Signal eingesetzt, und ihr Ausprägungsgrad wurde bislang mit mehreren Indikatoren für die physiologische Verfassung in Verbindung gebracht. Wir sammelten die Federn von Weibchen einer spanischen Population während des Nestbaus und bestimmten deren CORTf im Labor. Somit wurde CORTf in Federn aus der Mauser vor der Begattung gemessen, die von brütenden Weibchen als Zeichen ihrer sozialen Dominanz benutzt werden. Bei der Prüfung des Alters und der Körpergröße tauchte unter den AICc-Modellen die CORTf zur Erklärung der Größe des Stirnflecks in allen bestgeeigneten Modellen auf, zur Erklärung der Größe der Flügelflecken in den meisten bestgeeigneten Modellen. Die Größe sowohl der Stirn- als auch der Flügelflecken korrelierte negativ mit CORTf, letztere allerdings nicht signifikant. Dies deutet darauf hin, dass brütende Weibchen mit großen pigmentfreien Flecken während der ersten Mauser im Winterquartier einem niedrigen Stresslevel ausgesetzt waren, oder dass starke Signale aussendende Einzeltiere ein niedrigeres Aktivitätsniveau der Hypothalamus-Hypophysen-Achse aufweisen. The study was supported by project CGL2017-83843-C2-1 from Ministerio de Economía, Industria y Competitividad (MINECO, Spanish Government).

How environmental factors influence population dynamics in long-distance migrants is complicated by the spatiotemporal diversity of the environment the individuals experience during the annual cycle. The effects of weather on several different aspects of life history have been well studied, but a better understanding is needed on how weather affects population dynamics through the different associated traits. We utilise 77 years of data from pied flycatcher (Ficedula hypoleuca), to identify the most relevant climate signals associated with population growth rate. The strongest signals on population growth were observed from climate during periods when the birds were not present in the focal location. The population decline was associated with increasing precipitation in the African non-breeding quarters in the autumn (near the arrival of migrants) and with increasing winter temperature along the migration route (before migration). The number of fledglings was associated positively with increasing winter temperature in non-breeding area and negatively with increasing winter temperature in Europe. These possible carry-over effects did not arise via timing of breeding or clutch size but the exact mechanism remains to be revealed in future studies. High population density and low fledgling production were the intrinsic factors reducing the breeding population. We conclude that weather during all seasons has the potential to affect the reproductive success or population growth rate of this species. Our results show how weather can influence the population dynamics of a migratory species through multiple pathways, even at times of the annual cycle when the birds are in a different location than the climate signal. Supplementary Information The online version contains supplementary material available at 10.1007/s00442-020-04817-3.

The structure of the diet of passerine bird nestlings was analyzed in order to identify possible ways to reduce food competition between these species during the breeding period. We assumed that analysis of the effects of obtaining diets of heterospecific birds by nestlings in nature can help better understand their species-specific adaptations to living conditions, and we considered the case of joint nesting of the coal tit (Periparus ater (L. 1758)) (CT) and pied flycatcher (Ficedula hypoleuca (Pallas 1764)) (PF) in Moscow oblast as a key link. A PF male attracted a female to an artificial nest box, which has been already occupied by a CT pair. The females of both species incubated a mixed clutch sitting side by side. The CT nestlings hatched earlier than the PF nestlings, and the parents of both species began to feed them. The CT nestlings started to die one by one on the 4th day of joint feeding, and the last nestling died on the 11th day. This case encouraged us to compare the diets of nestlings from 22 broods of CTs and PFs in the same region. To compare the ratios of nestlings, we collected the portions of food that were delivered to nestlings by their parents and analyzed video recordings from the nests. The diet of PF nestlings was significantly more diverse than in CT nestlings (Berger–Parker reverse indices (1/d) were 3.01 and 2.11, respectively). Caterpillars and spiders (objects with a high content of carotenoids and taurine important for the development of nestlings) dominated in the CT diet. In PF feed, these objects occupied a much smaller portion. In addition to the above, compared with coal tits, PFs brought the following to nestlings: a significant number of objects with rough, highly chitinized covers (Coleoptera, Homoptera, etc.); objects with a sharp taste, such as true bugs (Heteroptera), ladybirds (Coleoptera, Coccinellidae), and millipedes (Diplopoda, Julidae); insects containing cantharidin toxin (soldier beetles, Coleoptera, Cantharidae). The nestlings developed successfully in PF nests to which parents brought such feed objects. The dimensional ranges of objects in the CT and PF diets completely overlapped. According to our opinion, the rougher, highly chitinized food and some poisonous insects (Cantharidae) in the PF diet make fundamentally important differences in the nutrition of PFs and CTs. Most likely, PFs have resistance to cantharidin and some other toxins that are contained in insects and therefore have a wider trophic niche.

The breeding biology and population dynamics of the Pied Flycatcher Ficedula hypoleuca in pine, mixed and deciduous forests in Skibotn, Northern Norway (69°20’N, 20°20’E), was studied during 33 years (1987–2019; in total 1775 completed first clutches). It was a period during which summer temperatures remained relatively stable, but late spring (May) temperatures tended to become warmer. The number of breeding pairs declined over the study period but varied less than in populations living in more harsh subalpine environments. In spite of the northern location, females started to lay eggs in a relatively late phenological phase of the environment and in relatively warm weather. The date of birch leafing and the date of egg-laying advanced during the study period, and they correlated with each other. Mean clutch size was 6.4 eggs, and mean number of fledglings/nest 4.6. Date of egg-laying was earlier and clutch size larger in deciduous forests than in pine and mixed forests, but this did not translate into better fledgling productivity. The main causes of nesting failure were predation by small mustelids and starvation in warm and dry summers. However, in the long run the population seemed to be able to maintain itself without immigration, i.e., act as a source population. The possibility that during warm climate periods of the past, breeding biology and population dynamics of Pied Flycatchers over large geographical areas might have resembled those in Skibotn is discussed. Cover photo: “Mummified” Pied Flycatcher nestling (age about 10 days) starved to death in Skibotn in the warm and dry summer of 1988. Photo: Antero Järvinen.

Hormones transferred from mothers to their offspring are thought to be a tool for mothers to prepare their progeny for expected environmental conditions, thus increasing fitness. Thyroid hormones (THs) are crucial across vertebrates for embryonic and postnatal development and metabolism. Yet yolk THs have mostly been ignored in the context of hormone-mediated maternal effects. In addition, the few studies on maternal THs have yielded contrasting results that could be attributed to either species or environmental differences. In this study, we experimentally elevated yolk THs (within the natural range) in a wild population of a migratory passerine, the European pied flycatcher (Ficedula hypoleuca), and assessed the effects on hatching success, nestling survival, growth, and oxidative status (lipid peroxidation, antioxidant enzyme activity, and oxidative balance). We also sought to compare our results with those of a closely related species, the collared flycatcher (Ficedula albicolis), that has strong ecological and life-history similarities with our species. We found no effects of yolk THs on any of the responses measured. We could detect only a weak trend on growth: elevated yolk THs tended to increase growth during the second week after hatching. Our results contradict the findings of previous studies, including those of the collared flycatcher. However, differences in fledging success and nestling growth between both species in the same year suggest a context-dependent influence of the treatment. This study should stimulate more research on maternal effects mediated by THs and their potential context-dependent effects.

Ficedula hypoleuca hypoleuca (Pallas, 1764) LITERATURE. — Green & Sayer (1979); Thonnérieux et al. (1989); Dowsett (1993); Balanca & de Visscher (1997); Borrow & Demey (2001, 2014); Portier (2002c); Balanca et al. (2007); Sinclair & Ryan (2010); Pavia et al. (2012); Dowsett et al. (2013). MUSEUM MATERIAL. — MCCI 3420, 3421. FIELD DATA. — eBird; GBIF; WABD. STATUS. — Palaearctic migrant. REMARK. — The records reported in literature and all the verifiable records refer to the nominal subspecies. The presence in Burkina Faso of the Iberian subspecies F. h. iberiae (Whiterby, 1928) and the Atlas Mountains subspecies F. h. speculigera (Bonaparte, 1850) reported for Western Africa by Borrow & Demey (2014) needs further investigations., Published as part of Boano, Giovanni, Belemsobgo, Urbain, Silvano, Fabrizio, Hema, Emmanuel M., Belemsobgo, Aristide, Dimobe, Kangbéni & Pavia, Marco, 2022, An annotated checklist of the birds of Burkina Faso, pp. 27-107 in Zoosystema 44 (2) on page 91, DOI: 10.5252/zoosystema2022v44a2, http://zenodo.org/record/5999691, {"references":["GREEN A. A. & SAYER J. A. 1979. - The birds of Pendjari and Arly National Parks (Benin and Upper Volta). Malimbus 1: 14 - 28.","THONNERIEUX Y., WALSH J. F. & BORTOLI L. 1989. - L'avifaune de la ville de Ouagadougou et ses environs (Burkina Faso). Malimbus 11: 7 - 39.","DOWSETT R. J. 1993. - Afrotropical avifaunas: annotated country checklists, in DOWSETT R. J. & DOWSETT- LEMAIRE F. (eds). A Contribution to the Distribution and Taxonomy of Afrotropical and Malagasy birds Tauraco Research Report 5, Tauraco Press, Liege: 1 - 322.","BALANCA G. & DE VISSCHER M. - N. 1997. - Composition et evolution saisonniere d'un peuplement d'oiseaux au nord du Burkina Faso (Nord-Yatenga). Malimbus 19: 68 - 94.","BORROW N. & DEMEY R. 2001. - Birds of Western Africa. Christopher Helm, London, 832 p.","BORROW N. & DEMEY R. 2014. - Field Guide of the Birds of Western Africa. II edition. Christopher Helm, London, 592 p.","PORTIER B. 2002 c. - Liste de l'avifaune du Ranch de Gibier de Nazinga. http: // environnement. wallonie. be / projet _ nazinga / PDF / Liste _ oiseaux _ Nazinga. pdf.","BALANCA G., CORNELIS D. & WILSON R. 2007. - Les oiseaux du complexe WAP. ECOPAS. Cirad, Montpellier.","SINCLAIR I. & RYAN P. 2010. - Birds of Africa south of the Sahara. II edition. Struik Nature, Cape Town, 768 p.","PAVIA M., BOANO G., SILVANO F. & MAMADOU K. 2012. - New bird records from southwestern Burkina Faso. Malimbus 34: 57 - 81.","DOWSETT R. J., ATKINSON P. W. & CADDICK J. A. 2013. - Checklist of the birds of Burkina Faso: 1 - 12. https: // www. africanbirdclub. org / [accessed 14 October 2013]."]}

Individual flexibility in breeding time is essential to respond to unpredictable changes in environmental conditions. Repeatability quantifies the consistency of the expression of phenotypes over time due to differences between individuals. Here, we estimate the repeatability of breeding date (laying date of first egg), hatching date and timing of pre-breeding events in a population of Pied Flycatchers Ficedula hypoleuca monitored over three decades in central Spain. We found low repeatabilities of breeding and hatching dates (respectively, R = 0.135 and R = 0) and among-year fluctuations (R = 0.276 and R = 0.218) in the expression of these traits. Repeatabilities of mating dates and of the interval between mating and egg laying were also very low (respectively R = 0.053 and R = 0) and among years (respectively R = 0.218 and R = 0.172), suggesting that Pied Flycatcher females are flexible to adjust their breeding schedule to current breeding conditions. We interpret the low consistency of traits related to breeding phenology as strong support for female phenotypic plasticity in breeding timing and the potential of such traits to respond to changing environmental conditions.—Le Vaillant, J., Potti, J., Camacho, C., Canal, D. & Martinez-Padilla, J. (2022). Low repeatability of breeding events reflects flexibility in reproductive timing in the Pied Flycatcher Ficedula hypoleuca in Spain. Ardeola, 69: 21-39.

In polygynous species with biparental care, mates are often acquired in succession. Most research has focussed on the cost of polygyny in secondary females, but primary females may also suffer from reduced paternal care. The likelihood of sharing a male may be higher for early laying females, which could counteract the fitness benefits of breeding early. In this study, we use 12 years of data on pied flycatchers Ficedula hypoleuca, to show that the likelihood of becoming a primary female of a polygynous male declines over the season. Moreover, we provide experimental evidence that early breeding elevates polygyny risk, through an experimental manipulation that introduced early breeding females to a population with later breeding phenology. We found that, independently of breeding date, primary females slightly more often experienced complete brood failures than monogamous females, but did not differ in number of fledged offspring among successful broods or number of locally returning recruits. However, apparent survival in subsequent years was substantially lower in primary females, indicating that they may compensate for reduced male care at the expense of future reproduction. Our study reveals that polygyny risk indeed increases with early breeding and entails a local survival cost for primary females. However, this cost is likely largely outweighed by fitness benefits of early breeding in most years. Hence it is unlikely that the increased polygyny risk of early breeding counteracts the fitness benefits, but it may reduce selection for breeding extremely early.

An original test to study the behavior of the pied flycatcher has been developed. The experimental arena can be used in field and laboratory study. It looks like a plus maze with a darkened central compartment, simulating an empty nesting box, and four entrances to the illuminated peripheral compartments of the arena. Birds demonstrate individual behavioral variability. They stay in the central compartment or leave it; make a different number of transitions between compartments and try to escape from the peripheral compartments through the transparent cover. Bird activity may depend on a number of factors, including the level of research activity and anxiety of individuals. This allows you to use this test to study the behavioral syndrome of the pied flycatcher.

The natural quantity of the pied flycatcher in deciduous, mixed, and coniferous forests and reproductive parameters in deciduous and mixed stands of subtaiga forests in the southeast of Western Siberia has been studied comparatively based on materials collected in the period from 1980 to 2017. The natural quantity of the species at the nesting period is greater in mixed and deciduous forests when compared to coniferous forests. Nesting density, clutch size, volume of eggs, success, and productivity of reproduction in nest boxes are higher in deciduous forests. The data on the natural quantity and breeding of pied flycatchers in the study area are compared with the similar indicators in the European part of the range.

In addition to direct mortality, predators can have indirect effects on prey populations by affecting prey behaviour or physiology. For example, predator presence can increase stress hormone levels, which can have physiological costs. Stress exposure accelerates the shortening of telomeres (i.e. the protective caps of chromosomes) and shorter telomeres have been linked to increased mortality risk. However, the effect of perceived predation risk on telomeres is not known. We investigated the effects of continuous predator threat (nesting Eurasian pygmy owl Glaucidium passerinum) on telomere dynamics of both adult and partially cross-fostered nestling pied flycatchers (Ficedula hypoleuca) in the wild. Females nesting at owl-inhabited sites showed impaired telomere maintenance between incubation and chick rearing compared to controls, and both males and females ended up with shorter telomeres at owl-inhabited sites in the end of chick rearing. On the contrary, both original and cross-fostered chicks reared in owl sites had consistently longer telomeres during growth than chicks reared at control sites. Thus, predation risk may cause a long-term cost in terms of telomeres for parents but not for their offspring. Predators may therefore affect telomere dynamics of their preys, which could have implications for their ageing rate and consequently for population dynamics. Electronic supplementary material The online version of this article (10.1007/s00442-019-04529-3) contains supplementary material, which is available to authorized users.

It is increasingly recognized that successful biodiversity conservation will necessitate active ecological restoration measures. In boreal forests, emulating natural disturbances is commonly used as a restoration tool for improving habitat quality for a range of sensitive species. We assessed the consequences of prescribed burning and artificial gap creation on the demographic parameters of an insectivorous bird, the pied flycatcher ( Ficedula hypoleuca ). This to improve our ability to develop strategies for successful ecological restoration aiming at improving the conservation status of boreal forest birds. Pied flycatchers reproduced equally well in nature reserves, forests subjected to ecological restoration and untreated control stands. Nestling body weight was found to be higher in stands restored through prescribed burning. Considering that nestling condition at the time of fledging is known to be positively related to survival rates after fledging, our results suggest a positive effect of prescribed burning on population dynamics and on local habitat quality. Our findings should encourage forest managers to actively use prescribed burning as a management tool in boreal forests to complement other conservation measures. However, one should be careful with generalizing these results to other bird species as they only are directly applicable to pied flycatchers. Still, they may potentially apply also to other insectivorous bird species with similar habitat requirements. In addition, it should be stressed that to maintain diverse boreal forest bird assemblages, heterogeneous landscapes are needed including both burned and unburned forest of different successional stages.

Background Nest construction is a key element of avian reproductive behaviour and the result is often a complex structure that is used for incubation of eggs, which represents an extended phenotype. It is known that nest construction is a plastic behaviour but the extent to which plasticity is observed in a single species with a wide geographical distribution is largely unknown. This study sought to better understand variation in nest size and composition across a very wide geographical area. The hypothesis suggested that location would affect size but not composition of nests of the European Pied Flycatcher (Ficedula hypoleuca). Methods Nests and reproductive data were collected from seventeen study sites, spread over 6° of latitude and 3.3° of longitude on the island of Great Britain. Dimensions of nests were measured before they were deconstructed to determine the masses and types materials used in the outer nest and the cup lining. Results Geographical variation was observed in base thickness of nests but not many other dimensions. Nests varied in composition but were mainly made of leaf, moss, bark, grass, root and fern. Moss was used more to the north and east of the study area compared with more leaf mass towards the south and west. The species of leaf and bark used in the nests varied between geographical locations. Additionally, the use of leaves or bark from a particular tree species did not reflect the incidence of the tree species in the immediate territory. Conclusions This study showed that nest composition was affected by geographical location over a wide area. Variation between nests at each location was high and so it was concluded that differences in nest composition reflect individual selection of materials but evidence is such that it remains unclear whether this is deliberate to fulfil a specific role in the nest, or simply opportunistic with birds simply picking up materials with the appropriate characteristics as they find them outside their nestbox.

Nesting home ranges of individual birds were regularly mapped in 2013 and 2014 from May to July along a permanent census route (3.15 km) in the dark-coniferous taiga on the southern slope of the bed of Lake Baikal. Based on the mapping results, the nesting densities and average sizes of the nesting home range of individual birds are estimated for each bird species and raster maps of spatial allocation (MSAs) at a scale of the raster grid of 50 × 50 m are obtained for each species. The degree of spatial conservatism (DSC) for each local population is inferred from the pairwise comparisons of the specific MSAs obtained on the same area (31.5 ha) in different years with the use of the Gamma rank correlation method. The dependence of the population habitat area on the DSC was demonstrated earlier (Cherenkov, 2017). The larger habitat area is found within the sample plot, an a less dependent individual spatial allocation within a population is observed in different years. Based on the estimated specific habitat areas, average sizes of the individual nesting home range, and estimated nesting density, the maximum possible nesting density and habitat saturation are calculated for each species. The population status is inferred from the degree of habitat saturation. Significant DSC estimates (p < 0.05) are obtained for nine species; their habitat areas and saturation are found. It is shown that habitat saturation in nonmigratory birds is twice as high an in migratory ones. On average, habitat saturation was 54–58% in nonmigratory birds and 26% in migratory ones (F = 9.1; p < 0.01). In the two species, the orange-flanked bush-robin (Tarsiger cyanurus Pallas, 1773) and taiga flycatcher (Ficedula (parva) albicilla Pallas, 1811), the habitat saturation is less than 20%, which indicates the presumably troubled status of their populations.

Understanding spatial linkages between areas used by migratory animals during the annual cycle is fundamental to their conservation. Stable isotope measurements of animal tissues can be a valuable tool in understanding spatial connectivity and migration phenology of migratory wildlife. We inferred natal origins of two migratory passerines, European Pied Flycatcher Ficedula hypoleuca and European Robin Erithacus rubecula, captured during autumn migration in the Italian Alps, by combining feather δ²H (δ²Hf) and ring recovery data. We used a spatially explicit likelihood‐based method to assign individuals to a precipitation δ²H surface calibrated to represent feather δ²H, together with the directional probability of origin from ring recoveries. The highest probabilities of origin for most individuals of both species were in central and north‐eastern Europe. Seasonal trends in δ²Hf, which described the species’ migratory phenology through the Italian Alps, were correlated with feather δ¹³C, δ¹⁵N and δ³⁴S values, indicating strong spatial discrimination related to continental patterns for these isotopes. We demonstrate how this combined information can define catchment areas and migratory connectivity of birds intercepted in the Alps. We highlight the importance of ringing data in defining directional priors to define Bayesian‐based probability surfaces using continental δ²Hf isoscapes, and how such information can be used to inform estimates of migratory connectivity.

The vegetation structure surrounding nest sites is a crucial component of habitat quality and may have large effects on avian breeding performance. Habitat quality reflects the extent to which the environmental characteristics of an area correspond to the preferred habitat characteristics of the species. The concentration of haemoglobin is considered a simple biochemical indicator of nestling body condition. We present results concerning the effects of variation in habitat characteristics on the concentration of haemoglobin in the blood of 14-day-old nestlings and breeding success of European Pied Flycatchers ( Ficedula hypoleuca) in a mature mixed deciduous forest in central Poland. The haemoglobin concentration of nestlings was higher when there were more native oaks and deciduous, native trees on the territory. Breeding success was reduced by the number of alien oak (the Red Oak, Quercus rubra) and other alien deciduous trees, but increased by the number of native oaks in the territory. This study was conducted on only one site so further research is needed to examine the broader applicability of our results. Our data support the idea that haemoglobin concentration may serve as a simple indicator of body condition in nestlings and is useful in field ecophysiology studies of European Pied Flycatchers.

Age-related variation in reproductive performance is central for the understanding of population dynamics and evolutionary processes. Our understanding of age trajectories in vital rates has long been limited by the lack of distinction between patterns occurring within- and among-individuals, and by the lack of comparative studies of age trajectories among traits. Thus, it is poorly understood how sets of demographic traits change within individuals according to their age. Based on 40 years of monitoring, we investigated age-related variation in five reproductive traits in female pied flycatchers (Ficedula hypoleuca) including laying date, clutch size, brood size, nest success (probability that a nest produces at least one chick) and egg success of successful nests (proportion of eggs resulting in a chick). We disentangled within- from among-individual processes and assessed the relative contribution of within-individual age-specific changes and selective appearance and disappearance. Finally, we compared the aging pattern among these five reproductive traits. We found strong evidence for age-specific performance including both early-life improvement and late-life decline in all reproductive traits but the egg success. Furthermore, the aging patterns varied substantially among reproductive traits both for the age of peak performance and for the rates of early-life improvement and late-life decline. The results show that age trajectories observed at the population level (cross-sectional analysis) may substantially differ from those occurring at the individual level and illustrate the complexity of variation in aging patterns across traits. Supplementary Information The online version contains supplementary material available at 10.1007/s00442-021-04963-2.

Telomere length and shortening rate are increasingly used as biomarkers for long-term costs in ecological and evolutionary studies because of their relationships with survival and fitness. Both early-life conditions and growth, and later-life stressors can create variation in telomere shortening rate. Studies on between- population telomere length and dynamics are scarce, despite the expectation that populations exposed to varying environmental constraints would present divergent telomere length patterns. The pied flycatcher (Ficedula hypoleuca) is a passerine bird breeding across Eurasia (from Spain to western Siberia) and migrating through the Iberian Peninsula to spend the non-breeding period in sub-Saharan Africa. Thus, different populations show marked differences in migration distance. We studied the large-scale variation of telomere length and early-life dynamics in the pied flycatcher by comparing six European populations across a north- south gradient (Finland, Estonia, England, and Spain) predicting negative effect of migration distance on adult telomere length, and of nestling growth on nestling telomere dynamics. There were clear population differences in telomere length, with English birds from mid-latitudes having the longest telomeres. Telomere length did not thus show consistent latitudinal variation and was not linearly linked to differences in migration distance. Early-life telomere shortening rate tended to vary between populations. Fast growth was associated with shorter telomeres in the early life, but faster nestling growth affected telomeres more negatively in northern than southern populations. While the sources of between-population differences in telomere-related biology remain to be more intensively studied, our study illustrates the need to expand telomere studies at the between-population level.

A current debate within population genomics surrounds the relevance of patterns of genomic differentiation between closely related species for our understanding of adaptation and speciation. Mounting evidence across many taxa suggests that the same genomic regions repeatedly develop elevated differentiation in independent species pairs. These regions often coincide with high gene density and/or low recombination, leading to the hypothesis that the genomic differentiation landscape mostly reflects a history of background selection, and reveals little about adaptation or speciation. A comparative genomics approach with multiple independent species pairs at a timescale where gene flow and ILS are negligible permits investigating whether different evolutionary processes are responsible for generating lineage-specific versus shared patterns of species differentiation. We use whole-genome resequencing data of 195 individuals from four Ficedula flycatcher species comprising two independent species pairs: collared and pied flycatchers, and red-breasted and taiga flycatchers. We found that both shared and lineage-specific FST peaks could partially be explained by selective sweeps, with recurrent selection likely to underlie shared signatures of selection, whereas indirect evidence supports a role of recombination landscape evolution in driving lineage-specific signatures of selection. This work therefore provides evidence for an interplay of positive selection and recombination to genomic landscape evolution.

In this study, we sequenced and annotated the complete mitochondrial genome of Ficedula hyperythra (Blyth, 1843). The mitogenome of F. hyperythra is 16,819 bp in length and contains 13 protein-coding, 22 transfer RNA, and 2 ribosomal RNA genes. Phylogenetic analysis based on 13 concatenated protein-coding genes showed that F. hyperythra clustered with other Ficedula species and had a close relationship with F. albicilla.