Search Results (32)

Pesticides remain among the most significant threats to biodiversity and natural ecosystems. Non-invasive methods, such as the analysis of bird faeces, have shown great potential for detecting pesticide exposure. In this study with a new approach, we analysed faecal sacs from nestlings of Blue tits (Cyanistes caeruleus) and Great tits (Parus major) to gain deeper insights into pesticide contamination during the breeding period. Samples were collected from three distinct sites near Münster, Germany. In total, we detected 65 substances from 57 different pesticides, as well as caffeine, with pesticides present in 16.07% of the 168 samples. Concentrations varied between species and sites and were higher for fungicides and insecticides in nests located closer to agricultural fields. While no direct effects on reproductive success were found, our results underscore the potential of faecal sac analysis as a valuable tool for spatially resolved pesticide monitoring. The novel, non-invasive approach to pesticide monitoring offers crucial exposure data on juvenile birds during their sensitive breeding period. Full article

Chromosomal inversions and copy-number variants (CNVs) drive genomic and phenotypic diversification in birds by reshaping recombination, gene expression, and genome architecture. Here, we report a complex structural polymorphism on great tit (Parus major) chromosome 1A that occurs in the Siberian population with a 19% heterozygote frequency. Using cytogenetic and genomic approaches, we show that this rearrangement combines a ~55 Mb paracentric inversion in the long arm with a dramatic (>30 Mb) expansion of the short arm driven by extensive amplification of multiple genomic loci. These include a region homologous to the poorly characterized FAM118A gene, whose paralog FAM118B has been recently shown to play a pivotal role in innate immune activation. This region is missing from the current reference genome assembly while present in ~20 copies on wild-type 1A chromosome and nearly twentyfold amplified in the rearranged variant. It contains a nested 630 bp tandem repeat, encompassing the entire exon 3, which has burst to a total of ~50,000 copies in the rearranged chromosome. While functional analyses are required to uncover the biological effects of the genomic features linked to this rearrangement, our results offer a unique framework for studying how complex structural polymorphisms drive genome innovation and adaptive diversity. Full article

Antipredator behavior can vary consistently among individuals, yet links between proactive nest defense and passive fear strategies are rarely quantified in the wild. We tested whether hissing, a conspicuous, snake-like display at the nest, predicts tonic immobility (TI) and breeding success in female Great Tits (Parus major). In pine forests in southeastern Latvia (2023–2024), we presented a taxidermic Great Spotted Woodpecker (Dendrocopos major) at nest-box entrances during incubation and scored whether females hissed and how many calls they produced. The same females were later assayed for TI by brief supine restraint when nestlings were 3–4 days old. Of 141 incubating females, 105 (74.5%) hissed. TI duration differed sharply between groups: non-hissing females showed significantly longer TI than hissing females. Nest failure was significantly lower in hissing than non-hissing female nests. These results reveal a strong negative association between proactive defense and passive fearfulness, and they show that hissing can translate into higher reproductive success in a Woodpecker-dominated predator environment. We conclude that defense strategies covary within individuals along a personality axis and that predator community composition may shape selection on these strategies. Full article

This study investigated the distribution of 29 legacy and emerging per- and polyfluoroalkyl substances (PFASs) in soil, nettles, invertebrates, and plasma and feathers of great tits (Parus major) of a terrestrial ecosystem near a fluorochemical plant. Additionally, the vertical distribution of PFASs in soil was assessed, as well as taxon-specific differences among terrestrial invertebrate species. Finally, associations between soil and biota, and among biological matrices, were assessed. Most accumulation profiles were dominated by long-chained PFASs, mainly perfluorooctane sulfonic acid (PFOS), while short-chained PFASs were less detected. Long-chained perfluoroalkyl carboxylic acids (PFCAs) adsorbed in the upper soil layers, while short-chained PFAS and perfluoroalkyl sulfonic acids (PFSAs) tended to migrate deeper. The several taxon-specific differences were likely due to dietary differences. Significant associations, especially for long-chained PFCAs and PFOS, were found among most matrices. This indicates that (1) these PFASs found in these matrices are most likely originating from the same pollution source, (2) there is a possible transfer of these PFASs between matrices, (3) there is bioaccumulation from one to another matrix, and (4) some matrices might be used as proxies to estimate PFAS concentrations in other terrestrial matrices. Finally, feathers accumulated more PFASs than plasma, as they were most likely exposed through different routes of exposure and PFAS affinity. Therefore, they are not suitable for internal PFAS monitoring but can provide complementary information about the exposure and about the presence/absence of PFASs in certain habitats. Full article

Winter bird feeders provide high-energy food for birds when natural food resources are in short supply. We performed an experimental study including two treatments and a control to investigate the reactions of eight passerine species visiting a winter feeder to the presence of a predator or a food competitor, measured by the number of visits and foraging time. We included in analyses the age and sex of the most numerous species, the Great Tit (Parus major). Our results showed that the number of feeder visits per 30 min differed significantly among species, treatments (predator, competitor, or control), and time intervals of time elapsed from the start of the treatment. The presence of food competitors and predation risk significantly deterred the birds from feeding at the feeder. The number of visits to the feeder by Great Tits was significantly affected by age (more frequent visits by immatures), sex (more frequent visits by males), treatment (less frequent visits by immatures during predation risk and by adults during both experiments), and the time elapsed since the start of the experiment (more frequent visits by adult females during the first eight time intervals after the start of the experiment). Surprisingly, the duration of the foraging visits to the feeder was significantly influenced by species (lower for all tit species compared to the other visiting species) and the time elapsed since the start of the treatment (shorter foraging duration during the first nine time intervals for Hawfinch (Coccothraustes coccothraustes), European Greenfinch (Chloris chloris) and European Robin (Erithacus rubecula)), but not by the treatment itself. This suggests that the decision to use the feeder is risk-dependent, but when birds choose to forage, their foraging time is risk-independent. Full article

Despite concerns about invasive Common Mynas (Acridotheres tristis), few studies have experimentally demonstrated their impact on native birds. Using a Before-After-Control-Impact (BACI) design with 142 nest boxes, we assessed how Myna presence affected House Sparrows (Passer domesticus) and Great Tits (Parus major) before (2009–2010) and after (2020–2021) their arrival in 2015. Half the boxes had large entrances accessible to all three species; half had small entrances accessible only to Great Tits. In a 2022 field experiment, we manipulated nest box entrances and used cameras to study Myna predation and nest usurpation. Following the establishment of Myna, House Sparrow breeding declined by 68.1%. Great Tits increased use of small entrance boxes by 59.9% and decreased use of large entrance boxes by 45.4%. Although overall Great Tit breeding increased, fledging success declined in large entrance boxes, but not small entrance ones. In the 2022 experiment, 46% (n = 26) of Great Tit nests were predated; Common Mynas were responsible for 50% of these cases and subsequently bred in the usurped nests. This study experimentally demonstrates that House Sparrow breeding numbers decrease and that Great Tits change their nesting behavior after the appearance of the Common Myna. Additionally, this research found that Common Mynas impact native species by predating and usurping nests. Installing small-entrance boxes can help manage Great Tit populations. Further research should explore nest box designs for House Sparrows and their impacts on other cavity-nesting and non-cavity-nesting bird species. Full article

The ability of terrestrial isopods (Crustacea: Isopoda: Oniscidea) to protect themselves effectively from predation by birds has never been tested. They are equipped with glands producing chemical substances; moreover, some species show conspicuous coloration, which might suffice as an aposematic signal. We evaluated the palatability of isopods to birds. We tested the responses of Parus major captured in the wild (and thus possessing some experience with common native isopod species) to the following isopod species: Porcellio scaber (native, inconspicuous), Oniscus asellus (native, moderately conspicuous), Armadillo officinalis (non-native, moderately conspicuous), Armadillidium versicolor (native, conspicuous), and Armadillidium gestroi (non-native, conspicuous). We compared bird responses to isopods with reactions to the Blaptica dubia, an edible roach very similar to isopods in size and appearance. Isopods were better protected from bird attacks than roaches; however, their color pattern did not affect the level of protection. Birds were able to differentiate isopods from the roach; in experiments, where we presented isopod and roach individuals together, the birds hesitated longer in attacking and observed both prey items for a longer time. Non-native species either profited from the generalization of the protection of native isopods or from neophobia. Some isopods elicited significantly more discomfort behavior in birds, suggesting differences in the chemical protection among the tested species. Full article

Bats serve as key ecological reservoirs of diverse microbial communities, including emerging viruses and antibiotic resistance genes. This study investigates the intestinal microbiota of two insectivorous bat species, Nyctalus noctula and Vespertilio murinus, at the Rostov Bat Rehabilitation Center in Southern Russia using whole metagenome shotgun sequencing. We analyzed taxonomic composition, functional pathways, antibiotic resistance genes, and virulence factors. Densoviruses, especially those closely related to Parus major densovirus, were the most dominant viral sequences identified. Metagenome-assembled densovirus genomes showed high sequence similarity with structural variations and clustered phylogenomically with viruses from mealworms and birds, reflecting both dietary origins and the potential for vertebrate infection. Functional profiling revealed microbial pathways associated with cell wall biosynthesis, energy metabolism, and biofilm formation. A total of 510 antibiotic resistance genes, representing 142 unique types, mainly efflux pumps and β-lactamases, were identified. Additionally, 870 virulence factor genes were detected, with a conserved set of iron acquisition systems and stress response regulators across all samples. These findings highlight the ecological complexity of bat-associated microbiota and viromes and suggest that synanthropic bats may contribute to the circulation of insect-associated viruses and antimicrobial resistance in urban settings. Full article

We followed the reproductive parameters of two species of tits, Great and Blue tits, over three decades (1993–2022), in three close habitats of the Mediterranean island of Sicily. We found that they regulated egg-laying dates in the same way, even though they had different dates. The anticipation of laying dates was inversely correlated with the temperature trends of February. The Great tit showed a significant anticipation of laying dates in all three habitats: in the pine woodland, an average anticipation of 19.8 days in 30 years was observed; in the oak woodland, an anticipation of 10.5 days in 30 years was seen; and in the mixed woodland, an anticipation of 13 days in 26 years was seen. The tendency to anticipate the laying date was also observed for the Blue tit in all habitats: in the pine woodland, it significantly anticipated the laying date by 14.4 days in 30 years, while in the oakwood, the anticipation was slightly smaller at 8.7 days in 30 years, and in the mixed woodland, an anticipation of 13.8 days in 26 years was observed. Breeding success did not change over the years for both species. Although we observed through the recoveries of ringed tits a movement of breeding individuals from the pine to the oakwood, we never observed the opposite. This is likely due to the greater availability of feeding resources in the natural woodland. In fact, tits in oak forests feed mainly on caterpillars; in other woodland types, they do not find caterpillars and feed on other arthropods. We hypothesize that most likely in Sicily, these tits, thanks to their phenotypic plasticity, will adapt to the present new conditions resulting from global warming, but if temperatures rise further, they will certainly face difficult times. Full article

Artificial light at night (ALAN) and noise pollution are two important stressors associated with urbanisation that can have a profound impact on animal behaviour and physiology, potentially disrupting biological rhythms. Although the influence of ALAN and noise pollution on daily activity patterns of songbirds has been clearly demonstrated, studies often focus on males, and the few that examined females have not included the potential influence of males on female activity patterns. Using free-living pairs of great tits (Parus major) as a model, we examined for the first time the effects of ALAN and noise pollution and their interaction on the onset of (vocal) activity in both members of a pair. We focused on the egg-laying phase, when both sexes are most vocally active. The onset of male dawn song, female emergence time from the nest box and the onset of female calling in the nest box were measured and used as a proxy for the chronotype. The repeatabilities for all chronotype proxies were high, with higher repeatabilities for males. Consistent with previous studies, ALAN advanced the onset of male dawn song, while it did not elicit a strong response in female emergence time. Additionally, our results suggest an indirect effect of ALAN on the onset of female vocal activity via acoustic interaction with the male. Noise pollution advanced the emergence time in females, while an interaction between ALAN and noise pollution was found for the onset of female calling. In agreement with previous studies, several covariables were shown to have an influence on the activity onset. Taking several proxies for chronotype into account, this study has provided robust evidence of effects of ALAN on male and female cavity-nesting songbirds during the egg-laying period. Full article

Due to the limited number of field studies investigating associations between environmentally relevant per- and polyfluoroalkyl substances (PFAS) mixtures and reproductive impairment, there is uncertainty as to whether birds are affected by PFAS pollution, whether species differ in sensitivity to PFAS, and whether the observed reproductive impairment is caused by PFAS or rather due to other potential confounding variables. Therefore, we investigated PFAS concentrations in eggs and blood plasma of great tit (Parus major) and blue tit (Cyanistes caeruleus) nestlings near a PFAS hotspot in Belgium, reproductive impairment, and associations between the accumulated levels and nestling body condition. In total, 29 eggs and 22 blood plasma samples of great tit clutches, and 10 egg and 10 blood plasma samples of blue tit clutches, were collected. Despite more types of PFAS being detected in eggs compared to plasma, only minor differences in profiles were observed between species. On the other hand, tissue-specific differences were more pronounced and likely reflect a combination of maternal transfer and dietary exposure post-hatching. Despite the high concentrations detected in both species, limited reproductive impairment was observed. Our results support previous findings that great tits and blue tits may not be very susceptible to PFAS pollution and provide evidence that other factors, including ecological stoichiometry, may be more important in explaining inter-species variation in PFAS accumulation and reproductive impairment. Full article

Anthropogenic pressures such as over-urbanization, intensive agriculture/forestry practices, and the development of energy farms alter natural landscapes. Intensive urban development poses the greatest threat to natural ecosystems. Habitat degradation, fragmentation, and loss are among the key factors behind the current rise of biodiversity loss. In this study, we hypothesized that urbanization advances the adaptation of forest bird populations to relatively new urban ecosystems. The study was conducted in Kaunas, Lithuania, located in Eastern Europe. Genetic samples were collected in the city, representing urban landscapes, and its surrounding forests. In total, 160 nest boxes were erected, of which 80 were placed in the urban areas and 80 in the forests. Using a set of microsatellite markers, we investigated the genetic differentiation, genetic diversity, gene flow, and population structure of two common forest bird species of the Paridae family, the great tit (Parus major) and blue tit (Cyanistes caeruleus), in forests and urbanized areas. We observed low but significant differences between urban and forest great tit and blue tit populations, proving relatively high population genetic diversity. We determined that cities’ spatial structure and fragmented natural habitats can influence the formation of small and isolated bird populations (subpopulations). Urban blue tits had higher genetic differentiation and a higher tendency to form subpopulations. In conclusion, forest birds can inhabit urbanized landscapes but both great tits and blue tits respond differently to urbanization-related changes. Full article

More than 40 hypotheses predict associations between features of nest architecture and at least one measure of reproductive success. However, quantitative studies of reproductive consequences of nest characteristics remain scarce. In addition, most studies were conducted on model species of which nests can be easily monitored with artificial nest-boxes. Here, we review the replicability of research protocols and findings in model species, with many repeat studies focusing mainly on nest-size components, animal-derived nest material, or fresh greenery in model species of secondary hole-nesting birds: Blue Tits (Cyanistes caeruleus), Great Tits (Parus major), Tree Swallows (Tachycineta bicolor), and Starlings (Sturnus spp.). The studies looked for correlations between nest traits and aspects of breeding performance that can be easily quantified in the field, such as clutch size, brood size at hatching or fledging, the percentage of eggs that hatch or fledge, or nestling characteristics assumed to reflect qualities associated with survival probabilities (e.g., morphometry, body condition, blood profiles). We discuss the consequences of poor replicability of research methodologies and provide explanations for why many of these studies reported poor associations between nest design and breeding success at different spatiotemporal scales. We also make suggestions for future research. Full article

Located at the crossroads of two continents and at the southeastern edge of the Mediterranean Basin, Anatolia was one of the most important Pleistocene glacial refugia in the Western Palaearctic. As part of the Irano-Anatolian, Caucasus and Mediterranean Basin biodiversity hotspots, this region is also home to a rich avian community including nearly 400 breeding species. Nevertheless, research addressing the genetic structure and diversity of local bird populations is limited, and information on glacial refugia in this region is still scant, especially when compared to other large Mediterranean peninsulas, namely the Balkan, Italian and Iberian ones. In this study, we contribute to filling this gap by addressing the biogeographic pattern of four common resident songbirds—the Eurasian blue tit (Cyanistes caeruleus), the great tit (Parus major), the Eurasian chaffinch (Fringilla coelebs) and the Eurasian blackbird (Turdus merula)—and one endemic species—the Krüper’s nuthatch (Sitta krueperi)—by amplifying two mitochondrial DNA genes in individuals from Anatolia (n = 329) and comparing their sequences to those of conspecifics from the rest of their distribution range across the western Palaearctic (n = 357) deposited in public databases. The overall genetic structure of these species is consistent with a scenario of isolation for multiple populations in different refugia across Anatolia and subsequent secondary contact in the wake of ice retreat, which makes this region a hotspot of genetic diversity for both widespread and endemic avian species. Full article

Increasing landscape transformations and urbanisation affect insectivorous bird populations in various ways such as food availability, breeding phenology, or reproductive success. Especially during the breeding season, many passerine birds rely on the availability of caterpillars as the main prey for their nestlings. Previous studies suggested that similar diet preferences of sympatric species may result in interspecific competition, as demonstrated for Blue and Great Tits in forest habitats. However, nestling diet and prey preferences in other habitats are not fully understood. Prey availability, especially caterpillars, is lower in cities than in forests, thus influencing prey choice and interspecific competition. Here we used faecal DNA metabarcoding to investigate if nestling diet composition of the two sympatric species Blue Cyanistes caeruleus and Great Tits Parus major varied among species and different habitats (forest, traditional orchards, and urban parks). Furthermore, we examined food availability by DNA barcoding of the arboreal arthropod communities among habitats and compared them to the nestling diet to infer parental prey selectivity. The study was carried out in central Germany from 2018 to 2019. Blue and Great Tits showed a diverse diet which was dominated by Lepidoptera in all habitats. Lepidopteran diet components were most similar between forest and orchard sites, as were the components with other arthropods between orchard and urban sites. Both tit species showed selectivity for the lepidopteran families Geometridae and Tortricidae in all habitats, and for Noctuidae (Lepidoptera), Tenthredinidae and Braconidae (Hymenoptera) in forest and orchard sites. As the tits showed preferences for mainly families of Lepidoptera, and Hymenoptera, our approach provides a baseline to support monitoring of these groups. Full article