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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).

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.

Breeding habitat choice and investment decisions are key contributors to fitness in animals. Density of individuals is a well-known cue of habitat quality used for future breeding decisions, but accuracy of density cues decreases as individuals disperse from breeding sites. Used nests remain an available information source also after breeding season, but whether such information is used for breeding decisions is less well known. We experimentally investigated whether migratory, cavity-nesting pied flycatchers (Ficedula hypoleuca) prospect potential breeding sites after breeding season and use old nests as a cue for future breeding decisions. In late summer 2013, forest sites were assigned to four treatments: (1) sites including nest boxes with old nests of heterospecifics (tits), (2) sites including suitable but empty nest boxes, (3) sites with unsuitable nest boxes, or (4) sites without any nest boxes. In the following year, we investigated pied flycatcher habitat choice and reproductive investment according to these “past” cues while also controlling for additional information sources present during settlement. Flycatchers preferred sites where tits had been perceived to breed in the previous year, but only if great tits were also currently breeding in the site and had a relatively high number of eggs. Old flycatchers avoided sites previously treated with suitable but empty cavities, whereas young flycatchers preferred sites where tits had apparently bred in the previous year. Also egg mass, but not clutch size or clutch mass, was affected by the combination of past treatment information and current tit abundance. Electronic supplementary material The online version of this article (10.1007/s00442-020-04629-5) contains supplementary material, which is available to authorized users.

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.

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.

Using information acquired from other individuals (social information use) is ubiquitous in animals and not restricted to within-species context. Some of the textbook examples of interspecific information use in the wild has been provided using apparent novel niche experiment approach, with migratory flycatcher species (Ficedula spp.) cueing on apparent nest site preferences (geometric symbols) and clutch sizes of resident great tits (Parus major) and blue tits (Cyanistes caeruleus) to choose their own nest site. However, the interpretation of these results has recently been challenged. It has been argued that there is no evidence that flycatchers visit tit nests to collect information about clutch size or that flycatchers are capable of “counting” tit eggs. Instead, it has been proposed that the decision-making patterns of flycatchers found in earlier studies resulted from aggressive interactions, not information use, between tits and flycatchers (termed owner aggression hypothesis). Here, I contribute to the debate around both hypotheses and specifically explore the remaining points of disagreement, related to the timing of flycatchers prospecting and the cognitive abilities needed to assess tit clutch size. I argue how interannual variation in phenology can explain the apparent discrepancy between the observed and predicted timing of flycatchers prospecting. I also argue why assessing tit clutch size neither requires “counting” eggs nor any sophisticated cognitive capacities. Finally, I propose experimental designs to test the hypotheses on the underlying mechanisms explaining the observed patterns, which will allow taking further leaps in resolving the selective interspecific information use vs. owner aggression hypothesis dilemma.

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.

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.

Why females engage in social polygyny remains an unresolved question in species where the resources provided by males maximize female fitness. In these systems, the ability of males to access several females, as well as the willingness of females to mate with an already mated male, and the benefits of this choice, may be constrained by the socio-ecological factors experienced at the local scale. Here, we used a 19-year dataset from an individual-monitored population of pied flycatchers (Ficedula hypoleuca) to establish local networks of breeding pairs. Then, we examined whether the probability of becoming socially polygynous and of mating with an already mated male (thus becoming a secondary female) is influenced by morphological and sexual traits as proxies of individual quality relative to the neighbours. We also evaluated whether social polygyny is adaptive for females by examining the effect of females’ mating status (polygamously-mated vs monogamously-mated) on direct (number of recruits in a given season) and indirect (lifetime number of fledglings produced by these recruits) fitness benefits. The phenotypic quality of individuals, by influencing their breeding asynchrony relative to their neighbours, mediated the probability of being involved in a polygynous event. Individuals in middle-age (2–3 years), with large wings and, in the case of males, with conspicuous sexual traits, started to breed earlier than their neighbours. By breeding locally early, males increased their chances of becoming polygynous, while females reduced their chances of mating with an already mated male. Our results suggest that secondary females may compensate the fitness costs, if any, of sharing a mate, since their number of descendants did not differ from monogamous females. We emphasize the need of accounting for local breeding settings (ecological, social, spatial, and temporal) and the phenotypic composition of neighbours to understand individual mating decisions

Funding – TAM thanks partial support by CEAUL (funded by FCT – Fundação para a Ciência e a Tecnologia, Portugal, through the project UID/MAT/00006/2019). Many species have advanced the timing of annual reproductive cycles in response to climatic warming, sometimes leading to asynchrony between trophic levels, with negative population consequences. Long-distance migratory birds, reliant on short seasonal food pulses for breeding, are considered particularly susceptible to such disjunction because late arrival may preclude optimal timing of egg-laying. It is unknown whether the relative timing of arrival and egg-laying is sufficiently plastic, in time and space, to enable an adaptive response when arrival times change relative to local food resources. We used citizen science data, describing pied flycatcher Ficedula hypoleuca arrival and egg-laying dates, to explore temporal (2013–2016) and spatial (across Great Britain) variation in the phenology of arrival, laying and their difference. To assess the long-term trend in arrival and laying at a single location, we used data from a long-term field study. The arrival-laying interval was consistently shorter in the north, driven by the contrast between spatial variation in arrival date and spatial invariance in laying date. To understand whether a short arrival-laying interval may have consequences for productivity, we assessed the association between this interval and clutch size. We found no statistically significant correlation between these two variables. To examine long-term changes in arrival and laying dates, we focussed on a single location in southwestern England. Both dates of first male arrival and first egg laid in a season advanced since 1986, with no evidence of interval shortening. Together, our results demonstrate spatial and annual variation in the arrival-laying interval, with no detected effect on fecundity. Thus, the interval from arrival to laying is likely dictated by spatially and temporally varying local conditions, suggesting these migrant birds may have the ability to adapt this interval to align with local conditions and mitigate potential mismatch impacts. Postprint

The star compass of birds, like the sun compass, is not innate. To possess either of them, birds have to observe the rotating sky and determine its centre of rotation (in the case of the star compass) or the sun's movement (for the sun compass). Young birds are believed to learn how to use the star compass before their first migration, even though the evidence of this is lacking. Here, we tested whether hand-raised Pied flycatchers (Ficedula hypoleuca) that had not established the star compass prior to their first autumn migration can gain it later in their ontogeny, in spring. We also attempted to examine whether the observation of diurnal celestial cues (the sun and polarized light) prior to autumn migration would affect the process of star compass learning in spring. When tested in the vertical magnetic field under the natural starry sky, the group of birds that observed the stars in spring as the first celestial cues were able to choose the migratory direction. In contrast, the birds that had never seen the stars were not able to use the nightly celestial cues in the vertical magnetic field. However, birds that had seen the daytime celestial cues till autumn and the stars at spring were disoriented, although this might be due to the small sample size. Our data suggest the possibility that the star compass may be learned in spring and emphasize the necessity for further research into the interaction of celestial compasses.

O_LITemperature is a key determinant of breeding phenology in temperate zone birds, with increasing spring temperature across years or large geographic gradients known to advance timing of breeding. It is less well understood how localised, territory-scale temperature variations effect territory occupation, breeding phenology and productivity, primarily due to a lack of fine-scale temperature data. C_LIO_LIWe examine the influence of temperature at the territory-scale, and its interaction with mean annual temperature, on territory selection and breeding outcomes of three co-occurring forest passerine bird species; two long-distance migrants (pied flycatcher Ficedula hypoleuca and wood warbler Phylloscopus sibilatrix) and one resident (blue tit Cyanistes caeruleus); all species dependent on seasonal invertebrate food for reproductive success. C_LIO_LISpring temperature was recorded at intersections of a 150m2 grid encompassing 417 ha of forest in South-West England 2015-18, with temperature across the study area interpolated from this point data. Breeding phenology and productivity from 672 nests across the three species was quantified, and general linear models used to examine the influence of territory temperature on breeding phenology and productivity. C_LIO_LIAll three species exhibited significant trends in reproductive traits associated with territory-scale temperature. Pied flycatchers settled in cooler territories first, where they raised more fledglings. Blue tits laid larger clutches in warmer territories in warm years and always laid earlier at warmer territories irrespective of annual mean temperature. Contrastingly, pied flycatcher and wood warbler breeding phenology was earlier at warmer territories in cool years and cooler territories in warm years, with wood warbler clutch size responding similarly to this interaction. Greater previous breeding experience and increased territory quality also predicted earlier breeding phenology and higher productivity for pied flycatchers. C_LIO_LIOur results show that local-scale spatial variation in temperature is associated with spatial variation in territory occupancy, breeding phenology and productivity in forest passerines. We suggest that the two migrant species may be best synchronised with their prey requirements in cooler years at a local population level while resident blue tits match local phenology at lower trophic levels across all years, potentially advantageous under warmer predicted climate change scenarios. C_LI

Pied Flycatchers Ficedula hypoleuca are known to be victims of nest killings in contexts of competition for nest boxes. However, there is only anecdotal information on their opposite role as perpetrators of nest takeovers and occasional killings of other songbirds. Over 31 years we examined whether competition with Great Tits Parus major over nest box ownership is a significant source of mortality for Pied Flycatchers and whether the increase in Pied Flycatcher populations affected the use of nest boxes by the smallest tit species, the Blue Tit Cyanistes caeruleus and Coal Tit Periparus ater, in two forests in the central Iberian Mountain Range. We found 31 Pied Flycatchers killed inside nest boxes. The Great Tit was the most frequent species to which the killings were attributed. Followed by Pied Flycatchers themselves and Nuthatches Sitta europaea. We confirmed the killing by Pied Flycatchers of at least two conspecific males and one incubating female Coal Tit, with one killer male identified. Large increases in population densities of flycatchers after nest box deployment in the two study areas seem to have triggered an intensification of agonistic interactions among their potential occupants, resulting in an increase of takeovers by Pied Flycatchers of nest boxes initially owned by the smallest tit species. Great Tits are not a serious threat for Pied Flycatchers breeding in the study area, most likely due to their preference for natural holes over the nest box types most frequently installed. The interactions of Pied Flycatchers with Blue and Coal Tits for the ownership of nest boxes do not seem to cause significant mortality in the species involved. However, aggressive usurpations of nest boxes by Pied Flycatchers surely have negative impacts on the reproductive success of the victims through their eviction from suitable nesting sites.—Potti, J., Camacho, C., Canal, D. & Martinez-Padilla, J. (2021). Three decades of crimes and misdemeanours in the nest box life of European Pied Flycatchers Ficedula hypoleuca. Ardeola, 68: 315-333.

Assortative mating depends on species distinctiveness in mating traits and preferences, which can be challenging to maintain when traits and/or preferences are learned. This is because learning may cause individuals to copy heterospecific signals. Juvenile songbirds possess innate sensory biases favouring them to learn and to prefer conspecific songs, but the effectiveness of these biases relies on consistent and sufficient differences between the songs produced by different species. However, mating signals, including learned songs, sometimes converge in sympatry, and the species-specific cues that individuals use to shape their preferences are often unknown. In Ficedula flycatchers, a stereotyped and highly species-specific alarm call is often incorporated as the first syllable of their songs. However, where the two species co-occur, pied flycatchers, Ficedula hypoleuca, learn to incorporate the introductory calls of the closely related collared flycatcher, Ficedula albicollis, into their songs. In this study, we investigated the role of introductory alarm calls for song discrimination in collared flycatchers, using playback experiments of both manipulated and unmanipulated songs on adults and nestlings within the hybrid zone of Oland, Sweden. We predicted that the introductory alarm call would be sufficient to trigger song responses, such that adults and nestlings would respond similarly to song phrases including the call, whether it is followed by conspecific or heterospecific notes. Our results provide evidence that the introductory alarm call is sufficient to trigger song discrimination in nestlings, but not in adult males, potentially due to their greater experience with songs and, therefore, subtler discrimination. Altogether, this study highlights the often-overlooked importance of calls within or associated with songs.

Among species that use similar resources, an individual may benefit by observing and copying the behavioural decision of a heterospecific. We tested the hypothesis of heterospecific social learning in passerine birds, namely that a migrant species, the Pied Flycatcher Ficedula hypoleuca, uses external markings on the nest cavities of a resident species, the Great Tit Parus major, as cues when choosing a nest site. Others have suggested that prospecting flycatchers assess the clutch size of tit “demonstrators” by entering their nest boxes and, assuming that a large clutch indicates a high-quality individual, will copy the nest appearance of tits with large, but not small clutches. During a 4-year period in Norway, we designed a similar study but did not find that flycatchers based their nest choice on the clutch size of tits. Neither were there any relationships between clutch size of the tit and its laying date, incubation behaviour, or the number of eggs visible through nest material during egg-laying so Pied Flycatchers did not use these indirect cues to assess quality of the tutor. Filming of tit nests showed that prospecting flycatchers did not enter tit nest boxes to assess the content. Indeed, incubating female tits only left their nest boxes for short bouts of unpredictable duration so there was little opportunity for flycatchers to inspect the nest contents unnoticed. Our study calls into question the mechanism of using the content of tit nests as public information for choosing traits of nest sites based on external characteristics. We suggest that similar studies of nest site choice in relation to possible social information transfer be replicated more widely.

Many species of birds incorporate feathers into their nest as structural support and to insulate the eggs or offspring. Here, we investigated the novel idea that birds reduce the risk of nest usurpation by decorating it with feathers to trigger a fear response in their rivals. We let prospecting birds choose between a dyad of nest-boxes in the wild, both containing some nest materials, but where one had a few white feathers and the other had none. All three species of cavity-nesting birds studied, the pied flycatcher Ficedula hypoleuca , the blue tit Cyanistes caeruleus , and the tree swallow Tachycineta bicolor , hesitated to enter boxes with white feathers. A similar avoidance of white feathers was found when the alternative nest-box of a dyad held black feathers. However, the birds readily collected white feathers that we placed in front of their nest-box, showing the fear of such feathers was context-dependent. We suggest that naive prospecting birds may perceive feathers in nests as the result of a predation event, and that owners decorate nests with bright feathers that can be seen from the opening to deter others from entering.

Climate change influences population demography by altering patterns of gene flow and reproductive isolation. Direct mutation rates offer the possibility for accurate dating on the within-species level but are currently only available for a handful of vertebrate species. Here, we use the first directly estimated mutation rate in birds to study the evolutionary history of pied flycatchers ( Ficedula hypoleuca ). Using a combination of demographic inference and species distribution modelling, we show that all major population splits in this forest-dependent system occurred during periods of increased climate instability and rapid global temperature change. We show that the divergent Spanish subspecies originated during the Eemian–Weichselian transition 115–104 thousand years ago (kya), and not during the last glacial maximum (26.5–19 kya), as previously suggested. The magnitude and rates of climate change during the glacial–interglacial transitions that preceded population splits in pied flycatchers were similar to, or exceeded, those predicted to occur in the course of the current, human-induced climate crisis. As such, our results provide a timely reminder of the strong impact that episodes of climate instability and rapid temperature changes can have on species' evolutionary trajectories, with important implications for the natural world in the Anthropocene.

We report the mitochondrial genome of Ficedula albicilla. The overall base composition of F. albicilla mitogenome is 29.49%A, 15.06%G, 32.98%C, and 22.47%T, with an A + T content of 51.96%. The total length of the sequence is 16,791 bp (13 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes, and 1 control regions). Phylogenetic analysis was performed based on the concatenated nucleotide sequences of cytochrome c oxidase subunit I and cytochrome b using the neighbor-joining method and the Kimura 2-parameter model in MEGA 7.0 with 1000 bootstrap replicates.

Ecological research is often hampered by the inability to quantify animal diets. Large-scale changes in arthropod diversity, abundance and phenologies urge the need to understand the consequences for trophic interactions. Diet composition of insectivorous predators can be tracked through DNA metabarcoding of faecal samples, but to validate the quantitative accuracy of metabarcoding, validation using free-living animals for which their diet can be approximated, is needed.This validation study assesses the use of DNA metabarcoding in quantifying diets of an insectivorous songbird. Using camera footage, we documented food items delivered to nestling Pied Flycatchers Ficedula hypoleuca, and subsequently sequenced the Cytochrome Oxidase subunit I (COI) in their faeces. Our special interest was to retrieve the relative contribution of arthropod taxa with a PCR-based protocol.Assessment of taxonomic coverage of the invertebrate COI primers LCO1490 and HCO1777, previously applied in insectivorous songbirds, demonstrated that COI barcodes were predominantly assigned to arthropod taxa, however, substantial amounts of reads (2–60%) were assigned to flycatchers. Modified primers reduced vertebrate reads to 0.03%, and yielded more spider DNA without significant changing the recovery of other arthropod taxa.To explore digestive biases, contents of stomachs and lower intestines were compared in eight adult male flycatchers, victims of competitors for nest boxes. Similarity in arthropod community composition between stomach and intestines confirmed limited digestive bias.With nest box cameras in 2013, 2015 and 2016, size-adjusted counts of prey items fed to nestlings were recorded, to approximate provided biomass of arthropod orders and families which allowed comparison with abundance of COI barcode reads in nestling faeces. The relative abundances of size-adjusted prey counts and COI reads correlated at R = 0.85 (CI:0.68-0.94) at order level and at R=0.75 (CI:0.67-0.82) at family level. Each common order and all common taxa within Lepidoptera, Diptera and Coleoptera were retrieved in similar proportions, while the taxonomic resolution was higher in barcodes than in camera records.This DNA metabarcoding validation demonstrates that quantitative arthropod diet analyses is possible in songbirds. We discuss the ecological application of our approach in approximating the arthropod diets in insectivorous birds.

Few studies on song learning have been conducted in the field. Male pied flycatchers (Ficedula hypoleuca) seem to learn song syllables in the breeding grounds. Adult males arrive first to the breeding grounds and sing more complex songs until they have paired. Early arriving juveniles may have more opportunities to learn new syllables from adult neighbours and develop more complex songs than later arriving juveniles. However, results suggest that arrival time is not important in song complexity development, but that males develop greater song complexity (repertoire size and song versatility) regardless as they age.

Direct and indirect effects of environmental pollution affect negatively to birds' breeding performance in both urban and industrial environments, but much less is known on how pollution and natural stress factors work together. In our long-term study (1991-2018), we explored whether industrial pollution and associated habitat changes increase the sensitivity of breeding parameters (hatching and fledging success, nestling growth) to temperature and precipitation in two insectivorous bird species, the great tit (Parus major) and the pied flycatcher (Ficedula hypoleuca). We found that both species are rather weather sensitive in terms of their fledging success, but especially in the F. hypoleuca, the negative effect was strengthened in a polluted environment. For both study species, all the breeding parameters, except growth of F. hypoleuca nestlings, were inferior in the polluted area and negatively affected by cold weather. Independent of pollution, the duration of rainy spells during the nestling period had an overall negative effect on fledging success of F. hypoleuca, and this effect became stronger at cold temperatures. The length of rainy spells was, however, positively associated with nestling wing length in both species, possibly because of better availability of some important food resources for wing growth in more humid conditions. The weather-pollution interactions in our study populations were not overwhelmingly strong, but those found in F. hypoleuca show that such interactions exist, they are species-specific and in our study system most likely associated to pollution-related resource (e.g. food) limitation. Higher sensitivity of F. hypoleuca to low temperatures is likely related to its less well-insulated nests and higher dependence on aerial prey, the availability of which is especially reduced during cold and rainy spells. Our study indicates that anthropogenic stress, such as pollution, has synergistic effects with natural stress factors affecting passerine birds' breeding performance.

Annual variation in the frequency of polygyny in the European pied flycatcher population is determined by a set of factors, with the primary factor being the sex ratio at the onset of the breeding season. The remaining factors, including individual characteristics of male and environmental conditions during this period, played a significant but secondary role. Facultative polygyny should be viewed as a mechanism to support the highest possible breeding productivity of individuals and populations, in unstable environmental conditions. It prevents an occurrence of nonbreeding females ready for mating and provides them with an opportunity to participate in breeding at a optimal time.

Woodpeckers are important primary excavators that produce nest-sites that are also used by several other cavity-nesting animals. However, the value of nest sites produced by different woodpecker species for other cavity-nesters is not generally known. We studied old Three-toed Woodpecker Picoides tridactylus cavities to examine their importance for other cavity-nesting forest bird species. Over a 31-year period (1987–2017), we annually monitored the occupancy of 655 cavities excavated by the Three-toed Woodpecker in 86 territories of the species in a 170-km2 area in southern Finland. Eight bird species used old Three-toed Woodpecker cavities for breeding, and the occupancy of these cavities by all secondary users was 21.3%. The expected mean number of lifetime occupancies by secondary cavity-nesters for a single cavity was 2.03. This is equivalent to a mean of two cavities occupied per territory per year, if we assume that Three-toed Woodpeckers produce a new cavity every year. The actual numbers of annually occupied cavities by secondary cavity-nesters can be substantially lower especially in territories that are not constantly occupied by the Threetoed Woodpecker. Based on the use of old cavities and densities of secondary cavity-nesting bird species, we conclude that cavities made by Three-toed Woodpeckers are most significant for the species itself, which accounted for 23.3% of nests in old Three-toed Woodpecker cavities. When Three-toed Woodpeckers reused an old cavity rather than occupy a freshly excavated cavity, 93% of cavities selected were originally excavated by Three-toed Woodpeckers. In addition, old cavities are important for the Pygmy Owl Glaucidium passerinum — up to 26–31% of breeding attempts were in old Three-toed Woodpecker cavities. The importance of old cavities for other hole-nesting bird species like the Pied Flycatcher Ficedula hypoleuca or the Great Tit Parus major was rather minor considering their densities within woodpecker territories.

Intensive forest management has caused a decline in the numbers of birds specialized on old growth. Understanding how forest stand attributes influence the distribution of these specialists has hence become a prerequisite for sustainable forest management. In this study, we evaluated the conservation value of managed forests for old-growth forest specialists using the poorly studied Semi-collared Flycatcher as an example. We applied a boosted generalized additive model to identify forest characteristics that determine the occurrence of the bird in Bulgaria. We found that on a national scale, forest stand age and percent cover of broad-leaved forests best explain the breeding distribution of the flycatcher. Although, forest stands became suitable habitat at an age of around 70 years for this species, stands in the interior forest featuring trees older than 160 years and composed of more than 80% broad-leaved trees were preferred by the species. At a local scale, the amount of dead wood positively influenced nest site choice of the flycatcher. In total, 22.3% of all studied broad-leaved forests in Bulgaria showed a predicted habitat suitability higher than 50%. High-stem forests that are old enough to develop old-growth characteristics had the highest potential to serve as habitat for the Semi-collared Flycatcher in Bulgaria. Therefore, we conclude that a decrease in logging of forests stands older than 160 years decreases the risk of decline of the Semi-collared Flycatcher.

Despite the interest of birds in reconstructing ancient environments, there are but few works concerning Quaternary avian remains. We have the opportunity to show in the present paper, the fossil avian remains of one of the more interesting natural, high-mountanous regions in southern Europe: the Spanish Pyrenees. In the central part of the Pyrenees, in the province of Huesca, Spain, five new paleontological sites with bird remains have been described: La Brecha del Rincon B-9 cave, the B-8 cave (Secus Range), Los Batanes C-4 (Tendenera Range), and C-15 and D-2 (Lecherines System). Their ages range from the Upper Pleistocene up to the Holocene. At least twenty three taxa are recorded: Galliformes indet., Lagopus muta , Coturnix coturnix , Bonasa bonasia , Rallus aquaticus , Columba oenas , Columba palumbus , Columba sp., Passeriformes indet., Ficedula hypoleuca , Ficedula sp., Lanius sp., Coccothraustes coccothraustes , Phoenicurus ochruros, Oenanthe oenanthe , Corvidae indet., cf. Perisoreus infaustus , Corvus frugilegus , Corvus monedula , Pyrrhocorax sp., Pyrrhocorax pyrrhocorax , Pyrrhocorax graculus , and Aves indet. In this work we present the highest-altitude paleontological record for Coturnix coturnix, Bonasa bonasia, Columba palumbus, and Corvus frugilegus, and the southernmost record of cf. Perisoreus infaustus . The new data go some way towards filling the gap in our information on avian assemblages in the Aragonese Pyrenees (especially by comparison with the vast knowledge that exist on the avian assemblages of the French Pyrenees sites) as well as the gap in what is known about avian assemblages in high-mountain systems, for La Brecha del Rincon B-9 and B-8 are the highest-altitude avian paleontological assemblages described in the Pyrenees Range.

Divergence in the onset of reproduction can act as an important source of reproductive isolation (i.e., allochronic isolation) between co-occurring young species, but evidence for the evolutionary processes leading to such divergence is often indirect. While advancing spring seasons strongly affect the onset of reproduction in many taxa, it remains largely unexplored whether contemporary spring advancement directly affects allochronic isolation between young species. We examined how increasing spring temperatures affected onset of reproduction and thereby hybridization between pied and collared flycatchers (Ficedula spp.) across habitat types in a young secondary contact zone. We found that both species have advanced their timing of breeding in 14 years. However, selection on pied flycatchers to breed earlier was weaker, resulting in a slower response to advancing springs compared to collared flycatchers and thereby build-up of allochronic isolation between the species. We argue that a preadaptation to a broader niche use (diet) of pied flycatchers explains the slower response to raising spring temperature, but that reduced risk to hybridize may contribute to further divergence in the onset of breeding in the future. Our results show that minor differences in the response to environmental change of co-occurring closely related species can quickly cause allochronic isolation.

Oxidative stress is the imbalance between the antioxidant capacity of an organism and the production of free radicals that can damage important biomolecules (lipids, proteins or DNA), affecting cellular senescence. Environmental conditions experienced by organisms can exert a strong influence on the development and expression of their phenotype, especially during early development and reproduction, which may determine access to territories, fecundity and survival. On the other hand, understanding the relationship between oxidative status and telomere dynamics -regions of non-coding DNA whose function is to stabilize the structure of chromosomes and with a fundamental role in ageing- is essential to fully appraise the mechanisms underlying the life-histories determined by the existing trade-offs between reproduction, maintenance and growth. Thus, the main objective of this thesis is to determine, from an ecological-evolutionary point of view, the role of oxidative stress in relation to the different life-histories developed by the birds, analyzing the influence of the nesting environment and the intrinsic and external factors affecting individuals during early development and reproduction. We have studied the physiological adaptations, in relation to oxidative stress, to the different trade-offs that birds face during their life cycle. The Pied Flycatcher (Ficedula hypoleuca) has been used as the study model. The study areas are located in the Sierra de Guadarrama, one in Montes de Valsain (Segovia), where there are 570 nest boxes, and another one in Lozoya (Madrid), with 100 nest boxes. Both experimental and observational studies have been carried out to analyze the influence of nesting environment and nest-dwelling ectoparasites on nestlings and parental individuals, the costs derived from the reproductive investment and the maintenance of sexual ornaments, the factors affecting the redox status in the early life and the relationships between reproduction, oxidative stress and ageing. Films of nests have been made to analyze parental care and, in all cases, blood samples have been taken from all individuals (adults and nestlings), for analysis of oxidative and biochemical parameters (oxidative damage, antioxidants, triglycerides, uric acid), sex (only in nestlings) and measures of telomeres (adults). In addition, photographs of adult plumage ornaments have been taken to analyze them as a sign of individual quality. This thesis contributes to verify the strong implication of the oxidative state in the trade-offs that sustain life-histories of birds. On the one hand, this thesis shows that the presence of old material in the nest does not affect all populations of ectoparasites equally, questioning the general idea that nest reuse is linked to higher infestations, with consequences on reproductive success and nestling growth. In addition, it is shown how the method to reduce ectoparasite loads of the nest can have uncontrolled effects on birds, which may lead to underestimation of the potential consequences of the presence of such ectoparasites on their avian hosts. We found experimental evidences of negative effects of ectoparasite loads on the oxidative status of adult females and developing chicks, which could have consequences on future survival and reproduction. This study also shows the associations between different components of the oxidative status of developing chicks and various environmental and intrinsic factors, which is essential to understand the importance of oxidative stress in the formation of the phenotype. On the other hand, it is suggested that different achromatic features of plumage can signal the individual capacity to cope with oxidative stress and the importance of the different phases of the reproductive cycle is emphasized to understand the role of oxidative stress as cost and constraint in reproduction. Finally, it is evidenced how the oxidative status is related with telomeres shortening (conseque

Growing animals face allocation problems whenever receiving suboptimal amounts of resources in very stochastic natural environments, possibly through a trade-off between growth and somatic maintenance. However, the extent to which such a trade-off exists has remained an open question. We used an insulin-like growth factor 1 (IGF-1) injection treatment in free-living pied flycatcher (Ficedula hypoleuca) nestlings to see how IGF-1 levels mediate the development of an antioxidant phenotype via glutathione peroxidase (GPx). Our study showed that IGF-1 levels underlie variation in GPx activity and provides important information for understanding the mechanisms behind the growth variation of passerines. This article is protected by copyright. All rights reserved.

Capsule: Breeding success in female Pied Flycatchers Ficedula hypoleuca is related to isotopic signature of feathers grown in Africa, suggesting wintering habitat links to breeding performance 5000km away.\ud Aims: Better understanding of interseasonal carry-over effects is a research priority, especially for declining migrants. We use stable isotope analysis to relate Pied Flycatcher winter habitat to summer reproductive success.\ud Methods: Flycatchers were captured in three UK woodlands in 2013-2015. An Africa-grown tertial was trimmed and analysed using Isotope Ratio Mass Spectrometry to quantify Nitrogen-15 (δ15N) and Carbon-13 (δ13C). In total, 135 samples were taken from 80 individuals.\ud Results: Wintering δ15N and δ13C differed significantly between years. δ13C correlated with lay date, such that birds with lower carbon levels (indicative of more mesic habitat) bred earlier. There was a significant correlation between wintering δ13C and productivity after allowing for year, site, and lay date; birds with low δ13C were more successful. This suggests δ13C links productivity directly as well as indirectly through phenological effects. δ15N did not relate to phenology or productivity.\ud Conclusion: This is the first evidence of carry-over effects between geographical regions for a European passerine. Conservation measures should focus on all aspects of seasonal cycles, not just breeding grounds.

Environmental pollution can exacerbate deterioration in fecundity with advancing age, directly via the toxic effects of pollutants or indirectly via pollution-related resource (e.g. dietary antioxidants) constraints. Since there are very few studies on age-related changes in reproduction with regard to pollution, we analyzed a long-term (25 years) set of reproduction data from a small insectivorous and migratory passerine bird, the Pied Flycatcher Ficedula hypoleuca, to determine whether female birds showed a faster age-related decrease in average breeding parameters in a metal-polluted area around a copper–nickel smelter than in the control area. In our population-level analysis, all the breeding parameters (clutch size, hatching success, fledging probability, and fledgling number) were lower in the polluted area. Nevertheless, none of them indicated a faster decrease with age in the polluted area. Clutch size and fledgling number increased after the first breeding, but showed no significant change later on. Hatching probability decreased slightly after the second breeding, while fledging probability showed no significant age-dependent variation. Our results suggest that moderate long-term pollution does not reduce the viability of our study population via a faster age-related decrease in fecundity.

SummaryChanges in land-use and climate are threatening migratory animals worldwide. In birds, declines have been widely documented in long-distance migrants. However, reasons remain poorly understood due to a lack of basic information regarding migratory birds’ ecology in their non-breeding areas and the effects of current environmental pressures there. We studied bird densities, spatial and territorial behaviour and habitat preference in two different habitat types in northern Ghana, West Africa. We study three common Eurasian-African songbirds (Willow Warbler Phylloscopus trochilus, Melodious Warbler Hippolais polyglotta and Pied Flycatcher Ficedula hypoleuca) in a forested site, heavily disturbed by agricultural activities, and a forest reserve with no agriculture. The three species differed in non-breeding spatial strategies, with Willow Warblers having larger home ranges and being non-territorial. Home ranges (kernel density) of the three species were on average 1.5–4 times larger in the disturbed site than in the undisturbed site. Much of the birds’ tree species selection was explained by their preference for tall trees, but all species favoured trees of the genus Acacia. The overall larger home ranges in the disturbed site were presumably caused by the lower density of tall trees. Density of Pied Flycatchers was 24% lower in disturbed habitat (not significantly different from undisturbed) but Willow Warbler density in the disturbed habitat was more than 2.5 times the density in undisturbed. This suggests that the disturbed habitat was less suitable for Pied Flycatcher but not for Willow Warbler. This difference is possibly related to differences in tree species preferences and suggests that at least for some species, presence of preferred tree species is more important than overall tree abundance. Such information is crucial for predicting consequences of habitat changes on larger scales and population levels, as well as for planning potentially migrant-friendly farming practices.

Tracking small passerines using miniaturised location tags is a rapidly expanding field of study. In a one-year study, we tested whether there were any short- or longer-term effects of fitting geolocators weighing 3% of body mass on male Pied Flycatchers Ficedula hypoleuca. In the deployment year, we compared adult provisioning rates to nestlings, nestling growth and nest success between nesting attempts in which adult males were fitted with a geolocator, with control nests where males had the same capture history but were not tagged. We found no difference between treatments in provisioning effort by males or their associated female two days after geolocator fitting, in terms of nestling growth, subsequent brood reduction or nest success. Return rate, arrival date on territories, timing and breeding parameters were compared between tagged and untagged males in the following breeding season. We found no difference in return rate or arrival date, and no difference in nest timing, fecundity or outcome. Our study suggests that fitting lightweight tags to small passerines need not affect behaviour, breeding or apparent between-year survival. However, tagging new species should still require assessment and comparison with well-matched control cohorts, and it should be recognised that tag effects could vary between years and populations, mediated by environmental conditions. This article is protected by copyright. All rights reserved.