Barn Swallows Hirundo Rustica Research Articles

UV-induced feather color change reflects its porphyrin content.

Pigmentary coloration is widespread in animals. Its evolutionary and ecological features are often attributed to the property of predominant pigments; therefore, most research has focused on predominant pigments such as carotenoids in carotenoid-based coloration. However, coloration results from predominant pigments and many other minority pigments, and the importance of the latter is overlooked. Here, we focused on porphyrin, an "uncommon" pigment found in bird feathers, and investigated its importance in the context of feather color changes in the barn swallow Hirundo rustica. We found that the "pheomelanin-based coloration" of the barn swallow faded after the irradiation of UV light, and this effect was particularly strong in the feathers of young swallows (nestlings and fledglings, here). We also found that it is not the predominant pigment, pheomelanin, but protoporphyrin IX pigment that showed the same pattern of depigmentation after the irradiation of UV light, particularly in the feathers of young swallows. In fact, the abovementioned age-dependent feather color change was statistically explained by the amount of porphyrin in the feathers. The current study demonstrates that a minority pigment, porphyrin, explains within-season dynamic color change, an ecological feature of feather coloration. The porphyrin-mediated rapid color change would benefit young birds, in which feather coloration affects the parental food allocation during a few weeks before independence, but not later. Future studies should not ignore these minor but essential pigments and their evolutionary and ecological functions.

Compensatory traits can explain the concave cost function of purely sexual traits.

The cost of ornamentation is often measured experimentally to study the relative importance of sexual and viability selection for ornamentation, but these experiments can lead to a misleading conclusion when compensatory trait is ignored. For example, a classic experiment on the outermost tail feathers in the barn swallow Hirundo rustica explains that the concave (or U-shaped) aerodynamic performance cost of the outermost tail feathers would be the evolutionary outcome through viability selection for optimal tail length, but this conclusion depends on the assumption that compensatory traits do not cause reduced performance. Using a simple "toy model" experiment, I demonstrated that ornamentation evolved purely though sexual selection can produce a concave cost function under the presence of compensatory traits, which was further reinforced by a simple mathematical model. Therefore, concave cost function (and the low performance of individuals with reduced ornaments) cannot be used to infer the evolutionary force favoring ornamentation, due to a previously overlooked concept, "overcompensation," which can worsen the whole body performance.

Defensive tolerance to parasitism is correlated with sexual selection in swallows.

Parasite-mediated sexual selection has been the topic of extensive research and enthusiastic debate for more than three decades. Here, we suggest that secondary sexual characters may not only signal parasite resistance but also defensive tolerance. We exemplify this possibility by analysing information on two sexually selected traits, annual reproductive success, and ectoparasitism in a barn swallow Hirundo rustica population followed for more than 30years. For each individual, we estimated the slope of the association between reproductive success and parasitism as an index of tolerance and subsequently explored the association with the expression of the sexually selected traits. In accordance with expectations of parasites playing a role in sexual selection, tail length was negatively related to load of chewing lice and nest size was positively related to tolerance to chewing lice. We discuss the importance of considering defensive tolerance for understanding the role of parasite-mediated sexual selection.

Anthropogenic noise interacts with the predation risk assessment in a free-ranging bird

Abstract Anthropogenic noise can affect a number of behavioral, physiological, and ecological aspects of animals from major taxonomic groups, raising serious conservation concerns. For example, noise pollution impacts communicative behavior and perception of signals, movements and distribution, as well as predator–prey interactions, such as hunting success or predator detection and predation risk assessment. We have carried out an experimental playback study, in which we investigated whether exposure to anthropogenic noise (sound of a tractor) distracts free-ranging barn swallows Hirundo rustica from paying attention to an approaching human “predator” (the “cognitive distraction” hypothesis), or whether noise leads to increased responsiveness to this “predator” (the “increased threat” hypothesis). The subjects were male barn swallows attending their breeding territories during the time when the females were incubating. We found that barn swallow males initiated flight at significantly greater distances to the approaching human “predator” in the noise treatment than during the quiet control trials. These results suggest that anthropogenic noise causes increased vigilance and reactivity rather than a distraction, enabling birds to avoid the “predator” more quickly. We further discuss the mechanism behind the increased alertness in response to noise and contrast the “increased threat” mechanism, usually tested in previous studies, with an alternative “cognitive sensitization” mechanism.

Intra‐ and interspecific variation in trace element concentrations in feathers of north European trans‐African migrants

The knowledge of migratory connectivity is important for understanding the potential drivers of populations and it is thus important for conservation implications. Migratory connectivity of species can be studied using exogenous, such as rings and transmitters, or endogenous markers, such as stable isotopes and trace elements. The use of trace elements has been much less frequently studied compared to stable isotopes. Trace elements can be studied from the feathers of birds and this does not necessarily require trapping of individuals. Here we studied the variation of 18 different trace elements in feathers of two long‐distance trans‐African migrants, willow warblers Phylloscopus trochilus and barn swallows Hirundo rustica, using body feathers of museum specimens of birds from Finnish breeding grounds. The trace elements were measured using laser‐ablation inductively‐coupled‐plasma mass‐spectrometry (LA‐ICP‐MS). We show that trace element concentrations were relatively stable along the rachis within the same feather except in Ni and S, which showed a quadratic pattern. In general, variation within feathers of the same individuals was smaller than in feathers between individuals for most elements. Furthermore, concentrations of 11 trace elements showed significantly higher concentrations in willow warbler feathers collected in spring than in autumn, moulted in African wintering grounds and European breeding grounds, respectively. Last, concentrations of seven trace elements were significantly higher in the spring feathers of willow warblers compared to barn swallows. This suggests that trace elements could be used to separate moulting grounds of the birds on the larger scale within the same species, but also sampling design should be carefully considered.

Male mate preference against tail‐elongated females in the barn swallow

AbstractThe function of female ornamentation in (inter)sexual selection is attracting increasing attention, but empirical field studies are mostly based on indirect measures such as mating patterns; direct evidence of male mate preference on female ornamentation while controlling for confounding factors is needed. Here, we performed model presentation experiments to study male mate preference in the barn swallowHirundo rustica,a model species of sexual selection. Although female tails are shorter than male tails in the barn swallow, they are still long and indicate female quality, possibly due to the differential costs of ornamentation. Although many correlational and experimental studies of live females have focused on long tails in female barn swallows over the last three decades, direct behavioral tests of male mate preference are lacking. In our sequential model presentation experiment, in which we repeated the trials with the same males, we found that males significantly reduced the number of pairing displays when presented with tail‐elongated female models compared to controls. The interaction between treatment and male tail length was far from significant. The observed pattern is inconsistent with the prevailing view that female ornamentation is maintained via male preference for more ornamented females; rather, it is consistent with the sexual mimicry hypothesis, in which females can avoid sexual and social harassment by mimicking males.

Aerial insect biomass, but not phenological mismatch, is associated with chick survival of an insectivorous bird

Recent insect abundance declines may have affected populations of insectivorous bird species but evidence for this is limited. Here, we use spatially overlapping 29‐year time‐series of aerial insect biomass and Barn Swallow Hirundo rustica numbers and breeding success from southern England to model the association between changes in invertebrate prey abundance, Swallow productivity and population trends. We found a positive statistical relationship between Swallow chick survival and the biomass of aerial insects available for chicks. In nests where at least one chick fledged, 96.7% of chicks were predicted to survive to fledging where there was high insect biomass (an average of 0.62 g/day), compared with 87.4% of chicks surviving to fledging where there was the lowest insect biomass (0.02 g/day; excluding the greatest and smallest 5% of insect biomass measurements). The amount of food available for chicks was largely a function of annual variation in insect abundance rather than the phenology of egg‐laying and insect emergence. However, we did not find a correlation between annual insect abundance and subsequent Swallow population growth. In the context of concerns about declining insect abundance, this study shows how changes in insect biomass may affect the productivity of an insectivorous bird at a regional scale, but with uncertain implications for population size at that same scale.

Reproductive Success of a Tropical Barn Swallow Hirundo rustica Population Is Lower Than That in Temperate Regions.

Temperate-tropical comparisons of avian life history traits are helpful to understand the different selective pressures placed on birds by different climate zones. Although there have been many comparative studies targeting multiple species in different regions, there are few comparative studies on the reproductive successes of the same species between tropical and temperate regions. In this study, we monitored the breeding activities of the Barn Swallow (Hirundo rustica) simultaneously at a single tropical site and a single temperate site in China, compared the breeding performances of the two populations, and investigated the effects of weather conditions on reproductive success separately. The clutch and brood sizes of the Barn Swallow at the topical site were significantly smaller than those at the temperate site. Furthermore, the breeding success of the Barn Swallow at the tropical site was significantly lower than that at the temperate site. The mean daytime temperature had a negative effect on the clutch size and brood size at both sites; it had a negative effect on nestling survival at the tropical site, but not the temperate site. This study will help us understand the adaptation strategies of widely distributed bird species in different environments, and how climate change will affect birds in different climate zones.

Farmstead modernization adversely affects farmland birds

Abstract Farmland biodiversity is declining at an alarming rate and various conservation measures have been implemented to reverse this negative trend. Farmsteads within agricultural landscapes were recently identified as farmland bird hotspots, so we ask whether the modernization of farmsteads has substantially reduced their conservation potential for farmland birds. We assessed the effect of farmstead modernization on 29 farmland bird species in rural landscapes on 97 dairy farms across the Czech Republic, investigating differences in farmland bird abundance and species richness, as well as nest abundance of declining farmland species breeding in buildings, by comparing new/modernized with old and mixed farmsteads. Additionally, we investigated how farmstead size and environmental variables influenced avian assemblages on farmsteads. Farmland bird abundance was almost 3‐fold lower in new/modernized farmsteads compared to mixed and old farmsteads (this difference was mostly driven by building‐nesters and noncrop‐nesters). Similarly, species richness was higher in old and mixed farmsteads compared to new farmsteads. Old cow sheds hosted more nests (both old and new nests; by a factor of 1.6–21) of house sparrows Passer domesticus, barn swallows Hirundo rustica and house martins Delichon urbicum compared to new cow sheds. Importantly, effects of environmental variables were negligible or smaller compared to the farmstead type, suggesting that bird abundance and species richness on farmsteads was primarily driven by farmstead modernization rather than the structure of surrounding farmland. Synthesis and applications. Farmstead modernization may have strong adverse effects on farmland bird populations due to reducing the availability of critical high‐quality nesting and foraging opportunities. Modernization is largely financed from existing EU funds, which directly conflicts with EU biodiversity strategies aiming at halting biodiversity loss. We therefore recommend (i) including compensatory measures to increase nesting and foraging opportunities for birds during farmstead construction/modernization, (ii) increasing awareness of these problems among critical stakeholders and (iii) increasing support to small‐sized traditional farms to retain and improve habitat conditions for declining farmland species.

Advanced post-juvenile moult in a Barn Swallow Hirundo rustica found in January 2023 in northern Scotland

ABSTRACT On 4 January 2023 DAP found a dead Swallow on a farm near Auldearn, Nairnshire (57°35’N 3°52’W). The bird appeared to have been dead for three to four weeks but was in a reasonably good state of preservation, probably as a result of the prolonged period of snow and very low temperatures which had prevailed in the area during the second and third weeks of December 2022. The bird, a juvenile, appeared to have reached a stage of moult of its flight feathers which might usually have only been expected in its winter quarters.

-

The habitat type and food availability always influence the population size of many organisms. Bird’s feeding pattern should be abstracted to complete avian community structure data. The agronomy main research farm of Orissa University of Agriculture and Technology is a well-managed multi-crop agro-ecosystem which provides a suitable ground for ecological research. In a multi-crop farmland, the association of Barn Swallow Hirundo rustica Linnaeus, 1758, with the Indian mustard Brassica juncea (L.) Czernajew, 1859 crops have been recorded for the first time while hovering only on this field. A flock of Barn swallows was recorded in 32 field visits while flying continuously over the Indian mustard field after flowering to ripening of fruit in the morning and sometimes in afternoon also. The range of the birds was recorded from 6 to 61 with a mean individual of 36.03 ± 15.37 hovering for 1.83 hr daily. This may be the behaviour for the feeding pattern of these flying insectivorous birds which was not seen in other crop-fields with same insect diversity describing it as not the only reason for this behaviour. To reveal this poorly understood behaviour of flying insectivore birds, a detailed long term behavioural study with gut content analysis is needed to explain the particular reason behind this behaviour of Barn swallows which will support the conservation of these birds and control their population decline.

Wing morphology covaries with migration distance in a highly aerial insectivorous songbird.

According to classical prediction of aerodynamic theory, birds and other powered fliers that migrate over long distances should have longer and more pointed wings than those that migrate less. However, the association between wing morphology and migratory behavior can be masked by contrasting selective pressures related to foraging behavior, habitat selection and predator avoidance, possibly at the cost of lower flight energetic efficiency. We studied the handwing morphology of Eurasian barn swallows Hirundo rustica from four populations representing a migration distance gradient. This species is an aerial insectivore, so it flies extensively while foraging, and may migrate during the day using a 'fly-and-forage' migration strategy. Prolonged foraging flights may reinforce the effects of migration distance on flight morphology. We found that two wings' aerodynamic properties-isometric handwing length and pointedness, both favoring energetically efficient flight, were more pronounced in barn swallows from populations undertaking longer seasonal migrations compared to less migratory populations. Our result contrast with two recent interspecific comparative studies that either reported no relationship or reported a negative relationship between pointedness and the degree of migratory behavior in hirundines. Our results may thus contribute to confirming the universality of the rule that longer migrations are associated with more pointed wings.

Long-Term Trends in Laying date and Fledged Young of Barn Swallow Hirundo rustica in Two Regions of the Netherlands

Since 1992, Dutch volunteers have monitored the breeding attempts of Barn Swallows on a systematic basis. For two regions – Noord-Veluwe and Twente – a dataset of 27 years (1992–2018) was available. This paper examines the timing of breeding and the number of fledglings per successful breeding attempt. As spring and summer weather in Western Europe became on average warmer during this period, we analysed whether Barn Swallows adapted to this shift. The laying date of first broods advanced on average 2.3 days per ten years. The average advancement of laying date of second broods was 2.9 days per decade. The average number of fledglings per successful breeding attempt was constant over time, but showed large inter-year-variation. First broods consistently produced 0.6 fledglings more than second broods. These results are in line with results from similar studies in Western Europe. Contrary to our expectations, neither large scale nor local weather parameters were found to explain the advancement of laying and the number of fledged young. It is essential to study key species like Barn Swallows during all stages of their life cycle over a long time span and large spatial scale to be able to unravel potential effects of climate change. Our study demonstrates that volunteers can contribute essential demographic data. Ideally, these demographic parameters would be monitored with individually marked (colour-ringed) birds. Frequent quality checks and feedback to volunteers are key to maximize the quality of the data collected through long-term volunteer surveys.

When Older Males Sire More Offspring—Increased Attractiveness or Higher Fertility?

In birds with extrapair mating, older males usually have higher fertilization success than younger males. Two hypotheses can potentially explain this pattern: 1) females prefer older, and often more ornamented males, or 2) older males invest more in reproduction and fertility than younger males. Here we studied factors associated with age-related male fertilization success in a population of barn swallows Hirundo rustica in Canada. We document that male fertilization success increased gradually up to a minimum age of four-year old. The age effect was especially strong for the number of extrapair offspring obtained and the occurrence of a second brood. The higher fertilization success of older males was also associated with an early start of breeding in spring. The length of the elongated outermost tail feathers, a postulated male ornament preferred by females, also increased with age (in both sexes), but it was not a significant predictor of male fertilization success within age classes. Male fertility traits, especially testis size, but also sperm motility and sperm velocity, increased significantly across age groups. Our results suggest that the higher fertilization success by older males is due to their higher reproductive investments and that their longer tails are an adaptation to early arrival on the breeding grounds.Significance statementThe barn swallow is a socially monogamous passerine with extensive extrapair mating. We found that males become more successful in siring both withinpair and extrapair offspring as they become older. Their increased fertilization success was associated with a higher reproductive effort as indicated by larger testes, more motile sperm, and an earlier start of breeding in spring. The length of the outer tail feathers increased with age in both sexes, but long tails did not enhance male fertilization success among males of the same age. Long tails are probably an adaptation to rapid migration and earlier arrival on the breeding grounds. Our findings suggest that the commonly observed age-related increase in male fertilization success in passerine birds is better explained by life history theory than by sexual selection theory.

Variation in diet composition and its relation to gut microbiota in a passerine bird

Quality and quantity of food items consumed has a crucial effect on phenotypes. In addition to direct effects mediated by nutrient resources, an individual’s diet can also affect the phenotype indirectly by altering its gut microbiota, a potent modulator of physiological, immunity and cognitive functions. However, most of our knowledge of diet-microbiota interactions is based on mammalian species, whereas little is still known about these effects in other vertebrates. We developed a metabarcoding procedure based on cytochrome c oxidase I high-throughput amplicon sequencing and applied it to describe diet composition in breeding colonies of an insectivorous bird, the barn swallow (Hirundo rustica). To identify putative diet-microbiota associations, we integrated the resulting diet profiles with an existing dataset for faecal microbiota in the same individual. Consistent with previous studies based on macroscopic analysis of diet composition, we found that Diptera, Hemiptera, Coleoptera and Hymenoptera were the dominant dietary components in our population. We revealed pronounced variation in diet consumed during the breeding season, along with significant differences between nearby breeding colonies. In addition, we found no difference in diet composition between adults and juveniles. Finally, our data revealed a correlation between diet and faecal microbiota composition, even after statistical control for environmental factors affecting both diet and microbiota variation. Our study suggests that variation in diet induce slight but significant microbiota changes in a non-mammalian host relying on a narrow spectrum of items consumed.

Male Barn Swallows Tolerate Nestling-Like Courtship Calls of Rival Males

Animals often exhibit conspicuous, and sometimes curious, courtship traits, such as nestling-like courtship display in birds, though modern studies of nestling-like courtship display (and calls) are virtually lacking. An exception is previous experiments on the barn swallowHirundo rustica, demonstrating that females are equally attracted to playback of two structurally similar calls, nestling-like male courtship calls and nestling food-begging calls. The experiments support the sensory trap hypothesis, i.e., that male signals mimic nestling stimuli to exploit female parental care for nestlings. However, female attraction might not be the sole function of nestling-like traits, and males might also have a sensory bias toward nestling-like traits, in which males would be less aggressive toward characteristics typical of immature individuals. Here, I conducted playback experiments to study the function of nestling-like male courtship calls in the context of male–male interactions. Playback of male courtship songs induced frequent approaches by neighbouring males, while nestling-like male courtship calls or nestling food-begging calls induced fewer approaches, though male responses to the latter two vocalisations increased when approaching the nestling period. The observed pattern indicates that, by mimicking immature individuals, males attract intended signal receivers (i.e., females) while avoiding interference from eavesdroppers (i.e., neighbouring males). This unique function can explain why species with parental care exhibit immature-like behaviour.

High turn-over rates at the upper range limit and elevational source-sink dynamics in a widespread songbird

The formation of an upper distributional range limit for species breeding along mountain slopes is often based on environmental gradients resulting in changing demographic rates towards high elevations. However, we still lack an empirical understanding of how the interplay of demographic parameters forms the upper range limit in highly mobile species. Here, we study apparent survival and within-study area dispersal over a 700 m elevational gradient in barn swallows (Hirundo rustica) by using 15 years of capture-mark-recapture data. Annual apparent survival of adult breeding birds decreased while breeding dispersal probability of adult females, but not males increased towards the upper range limit. Individuals at high elevations dispersed to farms situated at elevations lower than would be expected by random dispersal. These results suggest higher turn-over rates of breeding individuals at high elevations, an elevational increase in immigration and thus, within-population source-sink dynamics between low and high elevations. The formation of the upper range limit therefore is based on preference for low-elevation breeding sites and immigration to high elevations. Thus, shifts of the upper range limit are not only affected by changes in the quality of high-elevation habitats but also by factors affecting the number of immigrants produced at low elevations.

Highly Conservative Pattern of Sex Chromosome Synapsis and Recombination in Neognathae Birds.

We analyzed the synapsis and recombination between Z and W chromosomes in the oocytes of nine neognath species: domestic chicken Gallus gallus domesticus, grey goose Anser anser, black tern Chlidonias niger, common tern Sterna hirundo, pale martin Riparia diluta, barn swallow Hirundo rustica, European pied flycatcher Ficedula hypoleuca, great tit Parus major and white wagtail Motacilla alba using immunolocalization of SYCP3, the main protein of the lateral elements of the synaptonemal complex, and MLH1, the mismatch repair protein marking mature recombination nodules. In all species examined, homologous synapsis occurs in a short region of variable size at the ends of Z and W chromosomes, where a single recombination nodule is located. The remaining parts of the sex chromosomes undergo synaptic adjustment and synapse non-homologously. In 25% of ZW bivalents of white wagtail, synapsis and recombination also occur at the secondary pairing region, which probably resulted from autosome−sex chromosome translocation. Using FISH with a paint probe specific to the germline-restricted chromosome (GRC) of the pale martin on the oocytes of the pale martin, barn swallow and great tit, we showed that both maternally inherited songbird chromosomes (GRC and W) share common sequences.

Anthropogenic Resources Contribute to Settlement of Mud-Nesting Barn Swallows (Hirundo rustica) in an Arid Environment

Globally, bird populations are declining. This may be caused by human alterations of habitats formerly used by birds. Migratory birds show flexibility in resource use, however, a distinct move to a different habitat type demands investigation. The objective of this study is to understand the resources available to Barn swallows (Hirundo rustica) in White Sands National Park, New Mexico (WSNP) and how this species is utilizing this arid landscape. Results show that Barn swallows are aided by resources provided by the WSNP Visitor Center. Water and mud sources, perching and foraging sites, and protection from weather extremes and predators are all present and are exploited by Barn swallows in WSNP. Future research of this population could help determine if the Visitor Center is functioning as a sink or source habitat and how the establishment of a generalist species (with certain advantages) is competing with specialist species in this area. Understanding shifts in habitat types for migratory birds is important as conservation and management modeling continue to forecast suitable and available habitats for protected birds.

Lack of subspecies-recognition in breeding Barn Swallows (Hirundo rustica transitiva)

Assortative social interactions based on (sub)species recognition can be a driving force in speciation processes. To determine whether breeding Barn Swallows Hirundo rustica transitiva in Israel behave differentially towards members of their own subspecies, relative to a different, transient subspecies H. r. rustica and two sympatrically breeding species (Sand Martin Riparia riparia and House Sparrow Passer domesticus), we conducted a territory intrusion experiment near active nests using taxidermy models. Females responded less to the models than males, and the patterns of the recorded behavioral response traits co-varied statistically with sub- or species identity of the models, but none showed patterns of response selectivity for con(sub)specific model types only. These results do not support a role for subspecies recognition in the territorial intrusion responses of H. r. transitiva.