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Simple Summary: In May 2021, wildlife managers in Washington D.C., Maryland, Virginia, West Virginia, and Kentucky began receiving reports of sick, dying, and dead birds with eye swelling and crusty discharge, some of which also exhibited neurological behaviors. The public and licensed wildlife rehabilitators provided initial reports, while additional birds were received in Delaware, New Jersey, Pennsylvania, Ohio, Indiana, Tennessee, and Connecticut. The majority of reports involved fledgling common grackles (Quiscalus quiscula), blue jays (Cyanocitta cristata), European starlings (Sturnus vulgaris), and American robins (Turdus migratorius). Early in the event, the jurisdictions involved indicated a collective desire to work together in a regional response with consistent public messaging and collaboration among diagnostic laboratories. The U.S. Geological Survey National Wildlife Health Center (NWHC) facilitated conversations regarding event response among the affected jurisdictions and coordinated with other responding diagnostic laboratories. However, despite exhaustive collective efforts, no definitive cause(s) of illness or death have been determined, with some analyses still ongoing. This paper provides additional background on the event, outlines approaches taken by agencies to coordinate their response and communications with the public, and summarizes lessons learned that could be used to inform future preparedness and response plans. The ability to rapidly respond to wildlife health events is essential. However, such events are often unpredictable, especially with anthropogenic disturbances and climate-related environmental changes driving unforeseen threats. Many events also are short-lived and go undocumented, making it difficult to draw on lessons learned from past investigations. We report on the response to a mortality event observed predominantly in wild passerines in the eastern United States. The event began in May 2021 when wildlife rehabilitators and private citizens reported large numbers of sick and dead juvenile birds, mostly presenting as single cases with neurologic signs and/or ocular and periocular lesions. Early efforts by rehabilitators, veterinarians, state and federal wildlife agencies, and universities helped gather public reports and fuel rapid responses by government agencies. Collective efforts included live bird and carcass collections; submission to diagnostic laboratories and evaluation; information sharing; and coordinated messaging to stakeholders and interested parties. Extensive diagnostic evaluations failed to identify a causative pathogen or other etiology, although congruent results across laboratories have helped drive further investigation into alternative causes, such as nutritional deficiencies. This report highlights the strengths of a multi-agency, interdisciplinary investigation while exposing the need for an operational framework with approaches and resources dedicated to wildlife health. [ABSTRACT FROM AUTHOR]

Simple Summary: The birds of the order Passeriformes have seen limited advances in veterinary medicine, and knowledge about their parasitic fauna remains limited. Wildlife rehabilitation centers often receive injured or debilitated passerines, providing essential care for their recovery. However, many of these centers do not prioritize parasite screenings or necropsies for passerines, despite the valuable insights these procedures can provide. This study addresses this gap by offering crucial information on the parasites of wild passerines admitted to a wildlife rehabilitation center and introducing simple, cost-effective diagnostic methods that can be applied in this context, also serving as a foundation for future research. Our findings revealed that 94.1% (16 out of 17) of the passerines sampled were positive for parasites, including genera identified for the first time in Spain, demonstrating the importance of implementing and refining parasitological diagnostic techniques. The order Passeriformes is the richest and most abundant group of birds, but despite numerous parasites being identified in wild birds, this order has received limited focus. This study analyzed 17 passerines admitted to the Grupo de Rehabilitación de la Fauna Autóctona y su Hábitat (GREFA), a wildlife rehabilitation center in Spain, during October to December 2022. Necropsies were conducted to determine the presence of parasites, and intestinal contents were analyzed using fecal smear, flotation and sedimentation techniques and the McMaster method. Sixteen passerines (94.1%) were positive for parasites. Identified species included Monojoubertia microhylla and the genera Ornithonyssus sp., Diplotriaena spp., Serratospiculum sp., Porrocaecum sp., Capillaria spp., Syngamus sp., Strongyloides sp. and Brachylecithum sp., besides cestodes and coccidia. The comparative analysis of parasitological diagnostic techniques showed that the Willis flotation technique was effective for detecting coccidia. However, to obtain more accurate results for other parasites, it is important to complement this technique with direct examination or sedimentation techniques. Among the 12 passerines positive for coccidia, oocyst counts per gram of intestinal contents ranged from 100 to 30,450, with a median of 7350. This study provides valuable insights into the parasitic fauna of Passeriformes, serving as a cornerstone for future research and enhancing our understanding of these avian species. [ABSTRACT FROM AUTHOR]

The article presents the results of a study of the dynamics of autumn migration of small birds obtained during their captures with mist nets in the Kurgan Oblast in 2013, 2014 and 2016. Overall, we studied 55 species and report changes in their relative abundance from late July to mid-October as well as the starting, ending and peak dates of the migration for most species. Also, we determined the sequence of their departures from the region, classified the species by the dynamics and the number of main migration waves, defined the dominant species in the captures both for the entire migration period and for its different stages. Moreover, in the article we discuss long-term changes in the timing of autumn bird migration in the forest-steppe Trans-Urals, its direction, duration of stops, timing of migration of individuals from different age and sex groups.

Aims: Long‐term climate stability, contemporary climate and environmental heterogeneity have been linked to bird diversity patterns through their direct impacts on diversification rate, as well as through their indirect effects on plant species richness, which could also directly and indirectly affect bird diversity. This study aimed to quantitatively assess whether these potential drivers could indirectly affect bird species richness through their direct effects on the diversification rate in birds in eastern Asia. Location: Mainland China. Taxon: Birds. Methods: Using the distribution data of 1127 bird species across 320 prefecture cities in China and a phylogenetic tree of these bird species, we analysed the distribution patterns of bird species richness and diversification rate of all birds, passerine birds and non‐passerine birds, respectively. We also investigated their relationships with long‐term climate stability, contemporary climate, elevation range and plant diversity using ordinary least squares regression model and simultaneous autoregressive model. In addition, structural equation model was used to analyse whether these drivers could indirectly affect bird species richness through their direct effects on bird diversification rate. Results: The results showed that bird species richness and diversification rate were highest in southwestern China. Additionally, diversification rate for passerine birds was higher than non‐passerine birds and all birds. Regression analyses revealed that plant species richness was the variable most associated with bird species richness and diversification rate across the three groups. Notably, results from structural equation model indicated that plant species richness, elevation range and glacial–interglacial climate change can indirectly influence bird species richness by directly affecting diversification rates. Main Conclusions: These findings emphasize the importance of considering diversification rate when understanding the geographic distribution patterns of bird diversity. The direct and indirect effects of plant species richness, elevation range and glacial–interglacial climate change on bird diversity highlight the crucial role of mountain regions with higher plant diversity and stable paleoclimate in forming and maintaining biodiversity. [ABSTRACT FROM AUTHOR]

Temporal variation in resource availability, amplified by global change, may have strong impacts on species breeding at temperate and high latitudes that cue their reproduction to exploit seasonal resource pulses. This study examines how resource availability and parental care influence niche partitioning between and within age classes in the rufous‐collared sparrow, which provides extensive parental care. We hypothesized juveniles would exhibit narrower niches focused on high‐quality resources compared to adults, regardless of resource availability. We used stable isotope analysis to quantify individual and population niches in juveniles and adults across the breeding season in two cohorts experiencing contrasting resource landscapes. Contrary to our initial hypothesis, juveniles exhibited greater among‐individual diet variation and smaller total niche widths (i.e. higher levels of individual specialization, IS) during periods of high food availability in comparison to periods of food scarcity. Interestingly, total niche width and IS of adults remained stable across seasons despite a shift in trophic level, highlighting their potential role in providing a consistent diet for their young. These findings reveal a dynamic interplay between resource availability, parental care, and IS, with important implications for understanding population resilience under variable resource scenarios. The study also suggests that adult sparrows modify their provisioning strategies based on resources, potentially buffering offspring from environmental fluctuations. Understanding age‐specific responses to resource variation is crucial for predicting species responses to ecological conditions, particularly in regions like central Chile where seasonal resource limitation is expected to become more variable in response to climate change. [ABSTRACT FROM AUTHOR]

As offshore wind (OSW) energy expands globally, migratory songbirds are at risk of mortality from collisions with turbine blades, though the magnitude of this threat and which species are most vulnerable, remains poorly understood. Ecological vulnerability indices are commonly used to assess species' susceptibility to harmful factors, with results used to direct scarce research and monitoring resources to species showing relatively high vulnerability. These indices are based on the traits that elevate a species risk to adverse impacts (sensitivity), the overlap in occurrence between a species and the potentially harmful agent (exposure) and the influence of this exposure on the species' local or global persistence (resilience). We modified ecological vulnerability indices for seabirds to assess vulnerability of migratory songbirds to OSW related mortality. As a pertinent case study, we considered songbirds that fly across the Northwest Atlantic during their autumn migration. We utilized readily available information on each species' migratory behaviour, life history, and conservation status to calculate an index score that could range from 1 (lowest vulnerability) to 125 (highest vulnerability). We found scores of 3 to 55.2 for the 101 songbird species evaluated, with New World warblers (Parulidae) over‐represented among the highest scoring species. We found the scores to be sensitive to uncertainty in index components, highlighting the importance of considering scoring uncertainty when evaluating ecological vulnerability indices. Finally, we found that for seven of the top 10 highest scoring species, modest improvements in population trends had the potential to lower the scores substantially. Synthesis and applications. Our methodology is readily applicable to other regions where offshore wind (OSW) development is planned and songbird migration is common, allowing research and monitoring activities to be targeted to species most likely to be negatively affected by OSW facility encounters. [ABSTRACT FROM AUTHOR]

The pinyon jay Gymnorhinus cyanocephalus is listed as Vulnerable by the IUCN Red List of Threatened Species due to its continued decline in the wild caused by impacts to its unique pinyon-juniper woodland habitat. Recent reviews do not mention commercial trade as a threat and no information is given on use and trade at all. Here we provide evidence of recent international trade in pinyon jays observed in the European Union. We recommend listing the species in Appendix III of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) to enable the monitoring of international trade. Additionally, the desirability of a listing in a higher appendix of CITES at the next Conference of the Parties, as a more restrictive measure, should be assessed, as it may provide a necessary tool to prevent illegal international trade from becoming an additional threat for this unique North American songbird. [ABSTRACT FROM AUTHOR]

As species' ranges shift in response to human‐induced global changes, species interactions are expected to play a large role in shaping the resultant range dynamics and, subsequently, the composition of modified species assemblages. Most research on the impact of species interactions on range dynamics focuses on the effects of trophic interactions and exploitative competition for resources, but an emerging body of work shows that interspecific competition for territories and mates also affects species range shifts. As such, it is paramount to build a strong understanding of how these forms of behavioural interference between species impact landscape‐scale patterns. Here, we examine recent (1997–2019) range dynamics of North American passerines to test the hypothesis that behavioural interference impacts the ease with which species move across landscapes. Over this 22 year period, we found that fine‐scale spatial overlap between species (syntopy) increased more for species pairs that engage in interspecific territoriality than for those that do not. We found no evidence, however, for an effect of reproductive interference (hybridisation) on syntopy, and no effect of either type of interference on range‐wide overlap (sympatry). Examining the net effects of species interactions on continent‐scale range shifts may require species occurrence data spanning longer time periods than are currently available for North American passerines, but our results show that interspecific territoriality has had an overall stabilising influence on species coexistence over the past two decades.

Abstract The reaction of birds to the nest parasite, the European cuckoo Cuculus canorus, has been the subject of extensive testing in various aspects. However, while the cuckoo is a long-distance migrant, some of its hosts are sedentary species. In this study, we aimed to investigate whether species, primarily hosts, react to the presence of the cuckoo also in the winter season. This behaviour may involve an attempt to drive the parasite away from locations that will subsequently become their breeding sites. During playback experiments conducted in the winter of 2021/2022 in Poland, we demonstrated that numerous bird species react to the male cuckoo calls in winter. These calls may be perceived as a source of danger, particularly by cuckoo hosts, who responded to this call more frequently than non-hosts and the control species (pigeon). Nonetheless, the birds’ reactions were not strong, as they did not approach the source of the call. However, our results are constrained by the limited number of cuckoo host species wintering in Poland. To better evaluate the intensity of bird responses to the male cuckoo’s call during the non-breeding season, further studies should be conducted in regions where a greater variety of species, especially those most susceptible to parasitism, overwinter.

Climate change is altering the timing of seasonal events for many taxa.There is limited understanding of how northward/southward songbird migration follows or is limited by the latitudinal progression of seasonal transitions. Consistent environmental conditions that migrating birds encounter across latitudes likely represent or correlate with important resources or limiting factors for migration.We tested whether migratory passage—observed via radar—consistently tracked land surface variables and phenophases across latitudes in the US Central Flyway in both spring and fall.The daily temperatures, precipitation and vegetation greenness occurring on 10%, 50% and 90% cumulative passage dates changed substantially with latitude, indicating that most migrants experienced rapidly changing conditions as they headed north or south. Temperature did not limit the progression of migration in either season.Peak spring migration in the southern US occurred nearly 40 days after the spring green wave, the northward progression of vegetation growth, but nearly caught up to green‐up at 48° N. Spring migration phenology may have evolved to prioritize earlier arrival for breeding.Across all latitudes, peak fall migration coincided with the same land surface phenophase, an interval of 26 days prior to dormancy onset. Migrants may rely on phenological events in vegetation during fall stopovers.Considering that (a) migratory passage tracked fall land surface phenology across latitudes at a continental scale, (b) previous studies at local scales have demonstrated the importance of fruit during fall migratory stopover and (c) fruiting phenology in North America is occurring later over time while fall migration is advancing, the potential for mismatch between fall fruiting and bird migration phenology urgently needs further investigation. [ABSTRACT FROM AUTHOR]

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

Nest reuse is often observed in large- and medium-sized birds, including hole-nesters, while in smaller passerines building open-cup nests it is rarely recorded. In this note we report a case of multiple nest reuse, observed in a residential garden in Poland. The nest was located on the wall of a farm building partly overgrown by Boston Ivy at the height of 2.3 m. The nest was occupied eight times between 2007 and 2023 by three bird species: Grey and Pied Wagtails and Common Blackbirds. The nest was built by Grey Wagtails in 2007, but in 2009 it was reconstructed considerably by blackbirds. The Blackbird cup with mud lining survived until 2023 and contained all other nests. We suggest that the most plausible reason for multiple nest reuse was the high quality of this nest site. However, we also found that the nest was used during warm, dry springs but avoided when weather conditions at the beginning of the breeding season were adverse. We hypothesize that cold and wet springs – thought to be associated with high costs of reproduction – may have influenced birds' decision not to reuse the nest. To our knowledge, this is the longest case of nest reuse reported for passerines building open-cup nests. [ABSTRACT FROM AUTHOR]

In recent decades, the populations of many common bird species have greatly declined in Europe, particularly in farmland habitats. However, this decline has not affected every species, and to understand the mechanisms behind this interspecific variability, its relationship with several species-specific traits has been studied repeatedly. We used this approach to analyse long-term changes in the abundance of breeding passerines in farmland areas in northern Spain. Abundance changes were quantified in 2015 and 2016 by repeating the same line transects conducted in 1988/89 in three agricultural habitats located along a steep Atlantic-Mediterranean gradient in the province of Álava. We found that total bird abundance did not decline, as most species not closely linked to farmland habitats showed positive population changes, while the number of increasing and decreasing farmland specialists was similar. Specific traits explained a substantial proportion of the variability in abundance change, as warm-dwelling species and those occupying habitats with a complex vegetation structure showed more positive changes than those preferring colder conditions and more open habitats. These patterns can be explained by climate warming and by the increase in hedge and forest cover in the study area. Although we did not find a long-term decline in the overall abundance of the studied bird community nor in that of farmland specialists, open habitat species associated with a cool climate should be the focus of particular concern. RESUMEN : Los rasgos de las especies explican los cambios a largo plazo en la abundancia de aves nidificantes en medios agrícolas en Álava (Norte de España). Muchas especies de aves comunes en Europa han experimentado acusados descensos poblacionales en las últimas décadas, especialmente en medios agrícolas. Sin embargo, este declive no ha afectado a todas las especies, y para comprender los mecanismos que subyacen tras esta variabilidad interespecífica, se ha estudiado repetidamente su relación con diversos rasgos ecológicos propios de cada especie. En este estudio utilizamos este enfoque para analizar los cambios a largo plazo en la abundancia de los passeriformes nidificantes en áreas agrícolas del norte de España. Los cambios en la abundancia se cuantificaron repitiendo en 2015 y 2016 los mismos transectos realizados en 1988/89 en tres hábitats agrícolas situados a lo largo de un pronunciado gradiente Atlántico-Mediterráneo en la provincia de Álava. No se observó una reducción en el número total de aves, ya que la mayoría de las especies no asociadas estrechamente con medios agrícolas aumentaron su abundancia, mientras que el número de especialistas agrícolas que mostraron declives poblacionales fue similar al de aquellos que aumentaron. Los rasgos específicos explicaron una proporción sustancial de la variabilidad en los cambios de abundancia, ya que las especies propias de climas cálidos y las que ocupan medios con una estructura vegetal compleja mostraron cambios más positivos que las asociadas a temperaturas más frías y a hábitats más abiertos. Estos patrones se pueden explicar por los efectos del calentamiento global y del incremento en la cobertura de setos y bosques en el área de estudio. Aunque no se registró un declive a largo plazo en la abundancia total de las comunidades de aves estudiadas ni en la de especialistas agrícolas, las especies de espacios abiertos asociadas a climas fríos deberían ser objeto de especial atención.

The ability to rapidly respond to wildlife health events is essential. However, such events are often unpredictable, especially with anthropogenic disturbances and climate-related environmental changes driving unforeseen threats. Many events also are short-lived and go undocumented, making it difficult to draw on lessons learned from past investigations. We report on the response to a mortality event observed predominantly in wild passerines in the eastern United States. The event began in May 2021 when wildlife rehabilitators and private citizens reported large numbers of sick and dead juvenile birds, mostly presenting as single cases with neurologic signs and/or ocular and periocular lesions. Early efforts by rehabilitators, veterinarians, state and federal wildlife agencies, and universities helped gather public reports and fuel rapid responses by government agencies. Collective efforts included live bird and carcass collections; submission to diagnostic laboratories and evaluation; information sharing; and coordinated messaging to stakeholders and interested parties. Extensive diagnostic evaluations failed to identify a causative pathogen or other etiology, although congruent results across laboratories have helped drive further investigation into alternative causes, such as nutritional deficiencies. This report highlights the strengths of a multi-agency, interdisciplinary investigation while exposing the need for an operational framework with approaches and resources dedicated to wildlife health.

As the Arctic becomes increasingly accessible to the resource extraction industry, an understanding of the impacts of infrastructure and anthropogenic disturbance on tundra-nesting avian populations is critical. We conducted breeding bird surveys using point counts and Program for Regional and International Shorebird Monitoring (PRISM) rapid surveys at the Hope Bay Project, an underground gold mine in Nunavut, Canada, from 2007 to 2015. We examined the relationship between abundance of total birds, songbirds, and shorebirds with distance from infrastructure, anthropogenic disturbance (i.e., activity at the mine site), and environmental covariates. Contrary to our predictions, anthropogenic disturbance showed no significant effect on bird abundance for either survey type or bird grouping. However, total bird abundance was associated with distance from infrastructure for both survey methods. A relationship with distance to infrastructure, with variability in influence, was also present for songbird point count data and shorebird PRISM data, but was not significant for songbirds recorded during PRISM surveys. Habitat type played a vital role in determining avian abundance, with PRISM surveys showing that wet lowland ecotypes supported higher bird numbers, whereas point count data revealed a more nuanced habitat association, likely reflecting the specific habitat preferences of different songbirds. Our study highlights the need for strategic planning of industrial development, incorporating comprehensive monitoring and ensuring the protection of preferred Arctic-breeding bird habitats. By aligning development projects with environmental objectives, we can ensure the coexistence of industrial interests and the future of avian populations in the Arctic. [ABSTRACT FROM AUTHOR]

The cause of recent population declines in some farmland/hedgerow breeding bird species in the UK is related to a lack of cover and food resources in winter. In improved grassland areas some of those declines have been particularly acute and some have been shown to be related to the availability of grass and weed seed in winter. The provision of seed‐bearing crops as part of AES options has been shown to benefit some of these birds. Game crop plots sown on shooting estates for holding and driving gamebirds in autumn and winter have been shown to hold relatively high densities of farmland and wood‐edge birds during the winter. We studied breeding songbirds in hedges in a primarily improved grassland area in the SW of England where there are some large shooting estates that sow relatively large game crop plots (1–5 ha) in the landscape. In this study we found that otherwise similar hedges in terms of size and density near to those winter game crop plots, had between 1.5 and 2 times as many breeding resident songbirds per unit length the following spring compared to hedges further away from game crop plots. This was despite game management in these plots being wound down during February and in many cases, the crops themselves being removed by mid‐March. Hedges within approximately 350 m from game crop plots had more breeding birds. We discuss possible mechanisms and suggest that some passerines preferentially establish breeding territories in hedges near to game crops in late winter. We suggest how to distribute game crop plots to maximise any benefit in an improved grassland landscape. [ABSTRACT FROM AUTHOR]

Simple Summary: Wildlife has been described as a sylvatic reservoir for a multitude of pathogens. The interactions between wild birds, domestic animals, and humans in urban areas are high, so monitoring urban birds is key for the surveillance of zoonosis such as campylobacteriosis. This infection is mainly caused by thermophilic Campylobacter spp., and it is the most reported foodborne zoonosis in the European Union. This study aimed to evaluate the prevalence of thermophilic Campylobacter isolates and their antimicrobial resistance pattern in urban wild birds. Results showed that 16.8% of birds were positive for Campylobacter, with 82.4% of the isolates resistant to at least one antimicrobial. The taxonomic order of individuals, main diet, age, and season of sampling were significant factors associated with Campylobacter spp. carriage. Although the prevalence of Campylobacter was low, the rate of antimicrobial-resistant isolates is worrying, so similar studies should be included in the antimicrobial resistance surveillance programs. The increasing urbanization of ecosystems has had a significant impact on wildlife over the last few years. Species that find an unlimited supply of food and shelter in urban areas have thrived under human presence. Wild birds have been identified as amplifying hosts and reservoirs of Campylobacter worldwide, but the information about its transmission and epidemiology is still limited. This study assessed the prevalence of Campylobacter in 137 urban birds admitted at a wildlife rescue center, with 18.8% of individuals showing positive. C. jejuni was the most frequent species (82.6%), followed by C. coli and C. lari (4.3% each). The order Passeriformes (33.3%) showed significant higher presence of Campylobacter when compared to orders Columbiformes (0%) and Ciconiiformes (17.6%), as well as in samples collected during the summer season (31.9%), from omnivorous species (36.8%) and young individuals (26.8%). Globally, Campylobacter displayed a remarkable resistance to ciprofloxacin (70.6%), tetracycline (64.7%), and nalidixic acid (52.9%). In contrast, resistance to streptomycin was low (5.8%), and all the isolates showed susceptibility to erythromycin and gentamycin. The results underline the importance of urban birds as reservoirs of thermophilic antimicrobial-resistant Campylobacter and contribute to enhancing the knowledge of its distribution in urban and peri-urban ecosystems. [ABSTRACT FROM AUTHOR]

An accumulated rainfall of around 100 mm favoured the productivity of the specialist Moustached Warbler Acrocephalus melanopogon, but temperature had a negative effect. By contrast, temperature had a positive effect on the productivity of the generalist Reed Warbler Acrocephalus scirpaceus, whereas rainfall had almost no effect, although productivity also peaked when rainfall approached 100 mm. Understanding the extent to which climate and geography are driving the negative trend of Moustached Warbler productivity, and the stable trend of Reed Warbler productivity. Using data from a breeding bird monitoring ringing scheme in Spain (PASER; 1995 – 2021), we investigated the effects of seasonal rainfall and temperature patterns on the productivity of two sympatric warblers: the resident/short-distance migrant Moustached Warbler (occurring at nine ringing stations from a total of 129), and the generalist long-distance migrant Reed Warbler (57 out of 129 ringing stations). Analyses were performed using multi-adaptive regression splines (MARS). Between 1995 and 2021 geographical and site-specific factors drove annual productivity for both species, combined with rainfall and temperature. For the Moustached Warbler, geographical and site-related variables, together with the temporal changes (year), were more important than rainfall and temperature. For the Reed Warbler, temperature was more important than year but less than site and longitude. Warmer temperatures and a higher frequency of torrential rainfall events may compromise the conservation of the vulnerable Moustached Warbler in Spain due to the adverse effect on productivity. In contrast, increasing temperatures across Spain may benefit the widely distributed Reed Warbler. Thus, Moustached Warbler populations are likely to decrease, whereas Reed Warbler populations might increase. However, further research is needed to establish the impact of climate change on survival, and its implications for the population trends and dynamics of these two sympatric warblers. [ABSTRACT FROM AUTHOR]

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Extra‐pair paternity (EPP) is the consequence of the interactions between a social pair and extra‐pair males during the female's fertile phase in a specific social context and ecological environment. Although EPP occurs in many avian species, there is a lack of understanding of how environmental factors may impact its frequency. Accordingly, the relative importance of individual characteristics on the one hand, and of their immediate social environment on the other, may affect EPP repeatability and thereby the capacity of this trait to respond to selection. If EPP is an individual genetically based trait that may respond to selection, we expect it to be repeatable across breeding seasons. To check this possibility, we analysed the within‐individual repeatability in EPP of breeding males and females in two natural populations of Pied Flycatchers Ficedula hypoleuca in central Spain during three field seasons. We then studied the relationship between EPP and individual male and female traits (only some of which were themselves repeatable), as well as key context variables such as breeding synchrony and population density. Our results showed no repeatability for EPP in either sex. We found a positive association with laying date and stronger associations of EPP with male plumage and morphological traits than with female characteristics. We suggest that the variable social environment is an important modulator of EPP patterns, and that differences between field EPP studies in this respect may explain contradictory results in the same species, even in the same populations in different years. [ABSTRACT FROM AUTHOR]

Dispersal events offer a unique window into macroevolutionary processes, especially with respect to the effects of competition on diversification. Empirical studies testing alternative predictions of competitive effects are often limited in either geographic or phylogenetic scale. Here, we tested some of these hypotheses by comparing an assemblage of 16 oscine passerine clades, representing independent dispersal events into the Western Hemisphere, to their sister clades in the Eastern Hemisphere. We also compared the diversity of this assemblage of clades to an older, incumbent passerine clade in the Western Hemisphere, the suboscines. Specifically, we tested for ecological opportunity and incumbency-mediated constraints by analysis of clade-specific morphological disparities and rates of evolution relative to dispersal history. While there was no consistent outcome of oscine dispersal and macroevolution in the Western Hemisphere relative to their Eastern Hemisphere sister groups, most clades supported a role for ecological opportunity or incumbency effects, and such effects were better explained by differences in species accumulation than by differences in rates of trait evolution or colonization timing. This general pattern was not evident when comparing the entire oscine assemblage of the Western Hemisphere to the incumbent suboscine radiation; oscines and suboscines occupy comparable regions of functional trait diversity and, despite higher rates of trait evolution in oscines, these observations were consistent with simulated null expectations. This result suggests that oscine and suboscine assemblages may have evolved in relative isolation for a significant fraction of their history. [ABSTRACT FROM AUTHOR]

The Lesser Grey Shrike is a typical Palaearctic songbird for which we have limited knowledge of its migration ecology. All that is known about its non-breeding movements is inferred from observational data of birds on passage. The few available ring recovery data do not link breeding and African non-breeding grounds. By deploying two types of loggers, light-level geolocators and multi-sensor loggers, on birds from a declining Slovak breeding population, we present the first direct evidence for non-breeding grounds, loop migration, stopover sites and the timing of annual cycle events. With barometric data, we provide details on flight altitudes during migration. The two tracked birds migrated in a clear anti-clockwise loop to S Africa. Autumn migration tracks went through the Balkan Peninsula, Mediterranean Sea towards Libya with unusually long stays around N Chad and Niger. The next stopovers were in Angola, and the main non-breeding sites were in Botswana. Spring migration commenced on March 29 and April 7 and the birds took routes along East African countries, with stopovers later in Somalia and Saudi Arabia, before crossing the eastern Mediterranean Sea. Nocturnal migration dominated, but for three days in August, while crossing the Sahara Desert, the bird extended flights into the day with a sudden increase in flight altitudes at dawn. Flight altitudes were higher during barrier crossing and during the last phase of spring migration compared to the remaining periods, with the most extreme event recorded at 4530 m asl. [ABSTRACT FROM AUTHOR]

Torpor, a controlled reduction in metabolism and body temperature, reduces energy expenditure substantially. However, torpor expression in wild passerines is currently understudied. We show that skin temperature (Ts) of resting White-throated Treecreepers (N = 4) fell by ~ 5 °C on average in both summer and winter, independent of ambient temperature, but we could not confirm torpor use (Ts reduction > 5 °C). It is possible that roosting in tree hollows provides sufficient insulation to minimise energy loss, or torpor is used only during extreme conditions. Further studies are needed to characterise the physiological flexibilities of species and, therefore, their capability to cope with changing environmental conditions. [ABSTRACT FROM AUTHOR]

This study aimed to verify the diversity of ticks in wild birds of remnant fragments of the Atlantic Forest biome in the municipality of Piraí, Rio de Janeiro state, and to detect pathogenic agents in the ticks collected. Birds were captured between June 2016 and April 2017. The collected ticks were identified using a specific dichotomous key. Tick DNA was tested using polymerase chain reaction (PCR) for Borrelia spp., Rickettsia spp., Ehrlichia spp., Anaplasma spp., and Babesia spp. In total, 150 birds were captured, including 64 species, 18 families, and 5 orders. Of these, 22 (14.67%) of 18 different species were parasitized by Amblyomma spp. (n=7), Amblyomma longirostre (n=10), Amblyomma sculptum (n=1), and Amblyomma parkeri (n=21). Only one Amblyomma sp. amplified specific DNA fragments for Rickettsia amblyommatis, whereas the others were negative for Borrelia spp., Ehrlichia spp., Anaplasma spp., and Babesia spp. The avifauna play an important role in maintaining the life cycle of ticks, in addition to contributing to the dispersion of arthropods and the microorganisms transmitted by them. [ABSTRACT FROM AUTHOR]

Despite the development of technically advanced methods of studying bird migration, classical visual observations remain a source of valuable data allowing a broad analysis of the picture of diurnal migration at a given site. We employed visual observations to investigate the spatial and temporal pattern of diurnal migration of birds in the Polish part of the Carpathians. During autumns 2011-2013, 28 localities distributed over the area were surveyed by experienced observers, while 12 localities were researched in spring 2015. The data collected allowed the determination of passage intensity indices and the timing of migration for more than 100 species in autumn and about 70 species in spring. Mean passage intensity was more than 3 times higher in autumn than in spring, with the highest recorded in the first half of October and mid-March, respectively. Compared to autumn, the peak of diurnal migration was shifted to later hours in spring. The passage occurred primarily along the N-S axis, followed by the NE-SW axis. No consistent evidence of a barrier effect of the Carpathians – expressing as a reduction in passage intensity in intra-mountain locations or in higher elevated areas – has been detected in this study. The cluster analysis showed that the assemblage structure of migrants in the mountain regions located in the south of Poland (Carpathian Mts., Karkonosze Mts., Świętokrzyskie Mts.) were more similar to each other than to a region situated far to the north on the Baltic coast. [ABSTRACT FROM AUTHOR]

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ABSTRACT: In Brazil, the Atlantic Forest has been suffering from deforestation, which has had impacts on its flora, fauna, and microbiota. However, the fungal diversity present in these environments is little known and studied. In this study, a total of 90 samples of 45 wild birds (45 feathers and 45 feces) were collected in Ilha da Marambaia, southeastern Brazil. Filamentous fungi isolated from these samples were identified through macroscopic and microscopic characteristics. Some isolates were identified by molecular biology using the PCR technique. Acremonium, Alternaria, Aspergillus, Cunninghamella, Curvularia, Eurotium, Fusarium, Geotrichum, Neosartorya, Pestalotia, Paecilomyces, Penicillium, Rhizopus, Mucor and Syncephalastrum were identified. These results indicate the presence of saprophytic fungi species in the feathers and feces of wild birds of the capture site. Further studies should be conducted to elucidate if the mycobiota profile modifies with anthropization and if it interferes with bird health and environmental recovery.

A remarkably early nesting of a pair of White-throated Dipper (Cinclus cinclus) in December 2021 in northeastern Italy is reported and discussed by considering factors that may have influenced the breeding onset.

The immense diversity of plumage coloration exhibited by birds is the result of either pigments deposited in the feathers or microstructural arrangements of feather barbules. Some of the most common pigments are carotenoids, which produce bright yellow, orange, and red colors. Carotenoids differ from other pigments since birds cannot synthesize them de novo and must obtain them from the diet. Carotenoid pigments are usually associated with signaling and sexual selection, although they also have antioxidant properties and play a role in the immune response. Here, we hypothesize that carotenoid-dependent plumage coloration functions as a signal of a male's tendency to invest in offspring care because they play an important role in self-maintenance and may provide key information about individual quality; allowing females to obtain information about a male's tendency to invest in offspring care. Using phylogenetic comparative analyses across 349 passerine birds, we show that species that consume carotenoid-rich foods have more carotenoid-dependent plumage coloration than species with carotenoid-poor diets. In addition, carotenoid-dependent plumage coloration is associated with decreased male investment in offspring care. Our results suggest that investment in carotenoid-dependent plumage coloration trades off against male investment in offspring care and will likely have broad implications for our understanding of the ecological contexts that facilitate various evolutionary processes, such as sexual selection and signaling associated with plumage colors. [ABSTRACT FROM AUTHOR]

Costly interactions between species that arise as a by-product of ancestral similarities in communication signals are expected to persist only under specific evolutionary circumstances. Territorial aggression between species, for instance, is widely assumed to persist only when extrinsic barriers prevent niche divergence or selection in sympatry is too weak to overcome gene flow from allopatry. However, recent theoretical and comparative studies have challenged this view. Here we present a large-scale, phylogenetic analysis of the distribution and determinants of interspecific territoriality. We find that interspecific territoriality is widespread in birds and strongly associated with hybridization and resource overlap during the breeding season. Contrary to the view that territoriality only persists between species that rarely breed in the same areas or where niche divergence is constrained by habitat structure, we find that interspecific territoriality is positively associated with breeding habitat overlap and unrelated to habitat structure. Furthermore, our results provide compelling evidence that ancestral similarities in territorial signals are maintained and reinforced by selection when interspecific territoriality is adaptive. The territorial signals linked to interspecific territoriality in birds depend on the evolutionary age of interacting species, plumage at shallow (within-family) timescales, and song at deeper (between-family) timescales. Evidently, territorial interactions between species have persisted and shaped phenotypic diversity on a macroevolutionary timescale.

The optimal body mass hypothesis posits that the body reserves of wintering birds are balanced between the risk of starvation and predation. In this study, we tested whether the body mass of wintering Great Tits (Parus major) was higher under conditions of less predictable food resources. We compared body mass, body mass index, the speed at take-off, and apparent survival of Great Tit adult males wintering in small urban areas either near feeders providing permanent access to food for months or near feeders providing irregular access to food. Body mass and body mass index were greater, while take-off speed and apparent survival were lower, in birds wintering near permanent feeders than birds wintering near irregular feeders. Thus, urban birds, with their predictable access to high energy food, did not follow the fattening strategy predicted by the optimal body mass hypothesis. This study shows that regular excess amounts of high-energy food may affect urban birds’ physiological and behavioral strategies in a non-adaptive way. We recommend irregular feeding of wintering birds and the placing of feeders in places that are safe against attacking predators.

The objective of this study was to verify the accuracy of the quantitative PCR (qPCR) method for in vivo detection of Macrorhabdus ornithogaster. A total of 100 faecal and gastric mucosa samples from avian cadavers were investigated, using cytological and qPCR techniques (budgerigars, Fischer's lovebirds, red-crowned parakeets, scarlet-chested parrots, eastern rosellas, domestic canaries, zebra finches, white Java sparrow). Using qPCR, the probability of detecting positive samples of droppings was significantly higher than in the faecal smear microscopy (P

The Arctic Coastal Plain is one of the most important avian breeding grounds in the world; however, many species are in decline. Arctic‐breeding birds contend with short breeding seasons, harsh climatic conditions, and now, rapidly changing, variable, and unpredictable environmental conditions caused by climate change. Additionally, those breeding in industrial areas may be impacted by human activities. It is difficult to separate the impacts of industrial development and climate change; however, long‐term datasets can help show patterns over time. We evaluated factors influencing reproductive parameters of breeding birds at Prudhoe Bay, Alaska, 2003–2019, by monitoring 1265 shorebird nests, 378 passerine nests, and 231 waterfowl nests. We found that nest survival decreased significantly nearer high‐use infrastructure for all guilds. Temporally, passerine nest survival declined across the 17 years of the study, while there was no significant evidence of change in their nest density. Shorebird nest survival did not vary significantly across years, nor did nest density. Waterfowl nest density increased over the course of the study, but we could not estimate nest survival in all years. Egg predator populations varied across time; numbers of gulls and ravens increased in the oilfields 2003–2019, while Arctic fox decreased, and jaeger numbers did not vary significantly. Long‐term datasets are rare in the Arctic, but they are crucial for understanding impacts to breeding birds from both climate change and increasing anthropogenic activities. We show that nest survival was lower for birds nesting closer to high‐use infrastructure in Arctic Alaska, which was not detected in earlier, shorter‐term studies. Additionally, we show that Lapland longspur nest survival decreased across time, in concert with continent‐wide declines in many passerine species. The urgency to understand these relationships cannot be expressed strongly enough, given change is continuing to happen and the potential impacts are large. [ABSTRACT FROM AUTHOR]

Blood glucose plays an essential role in the body’s energy metabolism; however, sources of variation in baseline and stress-induced changes in glucose concentration remain poorly understood in tropical passerines. This study assesses intra-annual variation in baseline and stress-induced glucose concentration changes in two common free-living Afrotropical passerines, the village weaver (Ploceus cucullatus) (Müller, 1776) and the black-crowned waxbill (Estrilda nonnula) (Hartlaub, 1883), captured around Dschang, western Cameroon, using intrinsic (sex, body mass, moult and breeding status) and environmental (season, temperature and rainfall) variables as predictors. In black-crowned waxbills, we found that baseline glucose was significantly elevated in the dry season, with the same trend observed in the village weaver. Stress-induced elevations in glucose concentration were observed in the black-crowned waxbills in the dry season, but only when the temperature was fitted as a covariate. Village weaver females showed higher stress-induced changes in glucose compared to males. Body mass and moulting were not predictors of baseline or stress-induced changes in glucose concentrations. This study reveals that some fluctuations in glucose levels may be mediated by seasonal changes in temperature (but not rainfall), sex, and breeding status. [ABSTRACT FROM AUTHOR]

Annual migrations are energetically challenging for migratory passerines and represent a potentially stressful period of the annual cycle, particularly during brief refueling periods at stopover sites. Shoreline habitats near the Great Lakes in eastern North America support many landbird migrants; however, environmental factors—including food availability and unpredictable weather—may impact the health and physiological condition of these birds during refueling periods. The aim of this study at the Braddock Bay Bird Observatory was to use key blood metrics (plasma metabolite profiling and leukocyte counts) to assess annual and within-season variation in nutrient utilization and physiological condition of 3 species of Catharus thrushes with known variation in migration strategy and passage timing. We observed similar plasma triglyceride concentrations across species; however, glucose and uric acid were elevated in a short-distance migrant, the Hermit Thrush (Catharus guttatus). Furthermore, Hermit Thrush showed higher heterophil/lymphocyte ratios than Gray-cheeked Thrush (C. minimus) or Swainson's Thrush (C. ustulatus). Year was an important factor in all analyses exploring variables that may influence nutrient utilization or chronic stress. Our results suggest that thrushes with diverse migration strategies do not significantly differ in fat deposition patterns at the site, but end-of-season migrants may consume different resources and display increased chronic stress levels as they experience reduced food availability with the progression of autumn migration. We additionally propose that annual variation detected in this multi-year study underscores the importance of physiological condition metrics as tools for assessing yearly patterns in refueling performance at stopover sites, which is especially relevant in light of the continuing pressures of invasive species and environmental change. Las migraciones anuales son energéticamente demandantes para aves paserinas migratorias y representan un periodo potencialmente estresante en su ciclo anual, particularmente en los periodos breves de reabastecimiento en sus sitios de parada migratoria. Habitats ribereños cerca de los Grandes Lagos del este de Norteamérica mantienen a muchas aves terrestres migratorias; sin embargo, factores ambientales—incluyendo disponibilidad de comida y tiempo impredecible—puede tener un impacto en la salud y el estado fisiológico de estas aves en los periodos de reabastecimiento. El objetivo de este estudio en el Braddock Bay Bird Observatory fue usar indicadores sanguíneos clave (perfil metabólico de plasma y conteo de leucocitos) para evaluar la variación anual e inter-estacional de uso de nutrientes y de condición fisiológica de 3 especies de zorzales Catharus con variación conocida en estrategia migratoria y tiempo de paso. Observamos que las concentraciones de triglicéricos en plasma eran similares entre especies; sin embargo, la glucosa y el ácido úrico eran elevados en un migrante de corta distancia, el zorzal Catharus guttatus. Además, el zorzal C. guttatus mostró una relación más elevada de heterófilos/linfocitos que el zorzal C. minimus o que el zorzal C. ustulatus. El año fue un factor importante en todos los análisis que exploraron variables que podían influir en el uso de nutrientes o el estrés crónico. Nuestros resultados sugieren que zorzales con estrategias de migración diversas no difieren significativamente en patrones de depósito de grasa en el sitio, pero los migrantes del final de temporada pueden consumir diferentes recursos y mostrar niveles mayores de estrés crónico ya que experimentan una disponibilidad de alimento reducida con el avance de la migración otoñal. Adicionalmente proponemos que la variación anual detectada en este estudio multianual subraya la importancia de las métricas de condición fisiológica como herramientas para evaluar patrones anuales en el desempeño de la recarga en sitios de parada, lo que es especialmente relevante a la luz de las presione continuas de especies invasoras y de cambio ambiental. Palabras clave: aves paserinas, metabolitos del plasma, migración, reabastecimiento, relación H/L, uso de nutrientes. [ABSTRACT FROM AUTHOR]

We explored the influence of habitat structure on bird density and species richness in the poorly known bird communities in the steppes of Eastern Morocco, along a 200 km long N–S gradient of increasing aridity. The birds were surveyed, and habitat structure was measured in 44 transects regularly distributed along the gradient and during the winter and spring seasons in two consecutive years. After applying a principal component analysis (PCA), five axes were identified, including one related to the latitude–altitude–soil-type gradient and another describing the development of herbaceous vegetation. Generalized linear models were used to explore the relations between bird density and species richness with PCA axes in each season, considering both the entire community and groups of granivorous, insectivorous, and mixed-diet species. More than 90% of the birds were year-round residents, with larks dominating the community in both seasons. We conclude that a distinct multifactorial response can be identified for each functional group of species. In the winter, the community is mainly affected by the structure of the habitat, while aridity (and its assumed relation to primary production) is less influential. In the spring, habitat structure continues to have the greatest explanatory power, but location along the aridity gradient becomes more relevant. These findings reveal the interaction of the negative effects of climatic and anthropogenic changes in the habitat available to these bird communities, with a greater impact expected on birds with diets that include seeds, as well as a general shift of optimal breeding conditions toward more northerly latitudes. [ABSTRACT FROM AUTHOR]

We tracked departures of European Robins Erithacus rubecula stopping over during spring migration at Skagen, Denmark, and facing a sea crossing of more than 50 km. The Robins stopped over on average for 3.8 days (range 1–14 days, n = 15) with departure days being slightly warmer than stopover days (1.5°C warmer, P = 0.003). Departures were concentrated in the evening, on average during astronomical twilight, and toward the northeast (µ = 33.3°, r = 0.499, P = 0.021). The mean northeasterly departure direction is close to the standard migration direction. Most birds probably crossed the sea to Sweden and we observed no obvious reversed departure directions. [ABSTRACT FROM AUTHOR]

Simple Summary: Survival for birds can be challenging during the cold winter months in Northern Europe. Humans often provide food to wintering birds, thus, improving their winter survival. This study shows that excess underskin fat reserves of Great Tits wintering near permanent feeders can make them slow at take-off, which increases their exposure to predators. We suggest that caution should be taken when choosing a proper place to position bird feeders to prevent making birds at feeders easy prey for predators. The optimal body mass hypothesis posits that the body reserves of wintering birds are balanced between the risk of starvation and predation. In this study, we tested whether the body mass of wintering Great Tits (Parus major) was higher under conditions of less predictable food resources. We compared body mass, body mass index, the speed at take-off, and apparent survival of Great Tit adult males wintering in small urban areas either near feeders providing permanent access to food for months or near feeders providing irregular access to food. Body mass and body mass index were greater, while take-off speed and apparent survival were lower, in birds wintering near permanent feeders than birds wintering near irregular feeders. Thus, urban birds, with their predictable access to high energy food, did not follow the fattening strategy predicted by the optimal body mass hypothesis. This study shows that regular excess amounts of high-energy food may affect urban birds' physiological and behavioral strategies in a non-adaptive way. We recommend irregular feeding of wintering birds and the placing of feeders in places that are safe against attacking predators. [ABSTRACT FROM AUTHOR]

The increasing urbanization of ecosystems has had a significant impact on wildlife over the last few years. Species that find an unlimited supply of food and shelter in urban areas have thrived under human presence. Wild birds have been identified as amplifying hosts and reservoirs of Campylobacter worldwide, but the information about its transmission and epidemiology is still limited. This study assessed the prevalence of Campylobacter in 137 urban birds admitted at a wildlife rescue center, with 18.8% of individuals showing positive. C. jejuni was the most frequent species (82.6%), followed by C. coli and C. lari (4.3% each). The order Passeriformes (33.3%) showed significant higher presence of Campylobacter when compared to orders Columbiformes (0%) and Ciconiiformes (17.6%), as well as in samples collected during the summer season (31.9%), from omnivorous species (36.8%) and young individuals (26.8%). Globally, Campylobacter displayed a remarkable resistance to ciprofloxacin (70.6%), tetracycline (64.7%), and nalidixic acid (52.9%). In contrast, resistance to streptomycin was low (5.8%), and all the isolates showed susceptibility to erythromycin and gentamycin. The results underline the importance of urban birds as reservoirs of thermophilic antimicrobial-resistant Campylobacter and contribute to enhancing the knowledge of its distribution in urban and peri-urban ecosystems.

Seasonal differences of bird assemblages were studied using mist-netting method during four seasons (May, July, September, and December) in two years (2014 and 2021) in a secondary wetland habitat (7 mist-nets in willow grove, reed, and scrubland) in Zvolen town, central Slovakia. Altogether 54 species and 876 individuals of birds were captured during 24 days of eight trapping sessions (in 84 m of mist-nets at 7.3 ha study plot). The highest number of mist-netted species and individuals was found in July (36 species, 290 individuals), the lowest was in December (16 species, 153 individuals), pooled for both years. The most abundant species were breeding species Sylvia atricapilla, Parus major, Cyanistes caeruleus and Turdus merula. The characteristic reedbed birds included four Acrocephalus species, Locustella luscinioides, Emberiza schoeniclus, and scrubland species Luscinia megarhynchos, Sylvia communis and Remiz pendulinus. Seasonal differences in species number and abundance are discussed. Regular wintering was found in migratory species Prunella modularis and Erithacus rubecula north of the known winter quarters of their central European breeding populations. The site fidelity and between-season retraps were confirmed in 10 species and 54 individuals (18.5% of all mist-netted species and 6.2% of all individuals). Based on retrapped individuals, the resident species P. major, C. caeruleus, Aegithalos caudatus and T. merula were the most faithful to the site, whereas inter-seasonal retraps of migratory species were rare (e. g. Sylvia atricapilla, Luscinia megarhynchos and Phylloscopus collybita).

Simple Summary: This is the first case of an experimental study with a novel approach to analyze microsatellite instability (MSI) as a detection tool for genetic alterations in a wild population of birds, in this case for great tits (Parus major) being exposed to lead compounds. Although this preliminary study did not find any MSI in the analyzed microsatellite markers, it contributes to the examination of this molecular technique as a potentially applicable bioindication tool in ecotoxicological bird studies. We believe that certain issues should be considered in finding an explanation for our result. First, the exposure to lead was too low to induce genetic alterations. Second, the panel of microsatellite markers studied may have been unsusceptible to lead genotoxicity. Third, the time interval (5 days) between lead exposure and blood sampling for genetic analyses were too short to trigger genotoxicity. Further analyzes are needed to verify these findings and to evaluate the scope of application of the MSI analysis in wild bird population studies. Although many avian studies have investigated the toxic effects of lead on important biochemical and physiological processes, organ and system function, and behavior, studies evaluating the specific genotoxic effects of exposure to lead are scarce. Nowadays, rapid technological advances can provide new molecular techniques in this regard. In this study, as a novel approach in bird studies, we used a panel of ten microsatellite loci to investigate the microsatellite instability (MSI) in response to experimental lead intoxication in a common hole-nesting species, the great tit Parus major. For this purpose, an experiment based on an intentional single supplementation of a lead (II) acetate trihydrate compound was conducted, with the use of two different doses, applied to randomly chosen great tit nestlings from randomly selected broods, being at the stage of intensive erythropoiesis. Although this preliminary study did not find any MSI in the seven microsatellite markers retained for the final comparison, it contributes to the examination of this molecular technique in field conditions as being potentially applicable in ecotoxicological bird studies. We believe that certain issues should be considered in finding an explanation for our result. First, the single doses of lead used in this study may have been too weak to induce genetic instability. Second, the panel of microsatellite markers studied may have been unsusceptible to lead genotoxicity in general. Third, the relatively short time interval (5 days) between the experimental procedure (lead exposure) and the sampling of post-exposure material (blood) for genetic analyses could have limited the effect of lead genotoxicity. Further analyzes are needed to verify these findings and to evaluate the scope of application of the MSI analysis in wild bird population studies. [ABSTRACT FROM AUTHOR]

Citizen science data are increasingly used for biodiversity monitoring. However, concerns are often raised over the accuracy of species identifications in citizen science databases, as data are collected mostly by non‐professionals. Misidentifications can simultaneously generate two error types: false positives (erroneous reports of a species) and false negatives (lack of reports of the misidentified species). Large‐scale assessments of identification errors should provide insights into the strengths and weaknesses of citizen science data. Here we show that citizen science photographic data for birds are trustworthy overall, although problems arise in hard‐to‐identify bird groups. We reviewed over 104 000 images of 377 passerine species from the southern Neotropics (Argentina) stored in eBird – a large citizen science platform – and quantified erroneous reports to calculate precision and recall metrics as measures for data accuracy. Precision increases with fewer false positives and recall increases with fewer false negatives; hence, high values of precision and recall will mirror a higher data accuracy. We found that 97% of the photos of all species were correctly identified. Most species (77%; n = 291) showed high accuracy in their identifications (precision and recall > 95%), with 122 species showing no errors. A few hard‐to‐identify species (10%; n = 40) showed low levels of data quality (63–90% precision or recall). Similarly, few species (12%; n = 46) exhibited intermediate precision or recall scores (90–95%). Further, we uncovered the existence of a complex network of cross‐identifications composed of 272 species, with a predominance of tyrant flycatchers and ovenbirds, reflecting the strong traffic of errors that occurs within these families. To our knowledge, our study provides the first large‐scale quantification of identification errors in photos submitted by citizen science contributors. We underscore the relevance of performing such assessments to understand how identification errors are distributed across a database before analysing data, and provide tools for citizen science stakeholders to direct more specific efforts toward species that need an improvement in data quality. [ABSTRACT FROM AUTHOR]

The hyper‐diverse clade Passeriformes (crown group passerines) comprises over half of extant bird diversity, yet disproportionately few studies have targeted passerine comparative anatomy on a broad phylogenetic scale. This general lack of research attention hinders efforts to interpret the passerine fossil record and obscures patterns of morphological evolution across one of the most diverse clades of extant vertebrates. Numerous potentially important crown passeriform fossils have proven challenging to place phylogenetically, due in part to a paucity of phylogenetically informative characters from across the passerine skeleton. Here, we present a detailed analysis of the morphology of extant passerine carpometacarpi, which are relatively abundant components of the passerine fossil record. We sampled >70% of extant family‐level passerine clades (132 extant species) as well as several fossils from the Oligocene of Europe and scored them for 54 phylogenetically informative carpometacarpus characters optimised on a recently published phylogenomic scaffold. We document a considerable amount of previously undescribed morphological variation among passerine carpometacarpi, and, despite high levels of homoplasy, our results support the presence of representatives of both crown Passeri and crown Tyranni in Europe during the Oligocene. [ABSTRACT FROM AUTHOR]

Passerine birds are widely distributed and adapted to various habitats, therefore they are commonly exposed to, and infected with Toxoplasma gondii. The purpose of our project was to determine the prevalence and genotypes of T. gondii in 31 different species of passerines collected as mortalities due to window collisions in North-Central Oklahoma. DNA was extracted from breast tissue and subjected to PCR with primers that amplify a portion of the T. gondii B1 gene. Genotyping was based on a portion of the infected birds based on a multiplex PCR followed by RFLP of 12 T. gondii markers. Of 103 birds comprising 31 species, the overall prevalence (95% confidence interval) of T. gondii infection was 33.0% (24.1‒42.6%). Significant differences in the proportion of T. gondii in birds according to sex or weight were not observed. However, sample sizes of each species were small and prevented a robust analysis of T. gondii according to those biological variables. Genotyping of T. gondii in a subset of 13 infected individuals of 7 species revealed 4 genotypes, according to the Toxoplasma Data Base: #54, #139, #20, and #220. Our results, while hampered by a small sample size for each bird species, suggest that infection with T. gondii in Oklahoma, is common in both migrant and resident passerines. [ABSTRACT FROM AUTHOR]

Mist-nets are one of the most important tools for the capture of wild birds in ornithological research. The probability of capturing birds may vary by net height, which may drive capture biases. Such biases are rarely estimated, likely because of the relatively high cost and effort associated with constructing and operating elevated mist-net rigs where multiple mist-nets are stacked above one another. Therefore, a low-cost and -effort method to collect capture height data may allow broader investigation and better accounting of potential bias in existing banding protocols. Here, we investigate whether recording net panel of capture (with net panels indicating capture height, e.g., “upper panel”) in ground-level mist-nets provides sufficient information to estimate capture height biases and compare these estimations to those obtained with traditional elevated mist-net rigs. Of 29 taxa analyzed, we detected elevated capture biases for 11 (37.9%) and ground-level capture biases for seven (24.1%). When compared to estimates derived from elevated mist-net rigs at the same study site, we found high agreement with ground-level biases (75.0%) and low agreement with elevated biases (23.1%). These results suggest panel height of ground-level nets is a reliable method to estimate ground-level biases; however, scale of sampling may influence elevated biases, particularly for species that center their activity at the mid-story. Recording panel height may be quickly integrated into a station’s processing protocols and broader application may improve our understanding of these biases.

The objective of this study was to verify the accuracy of the quantitative PCR (qPCR) method for in vivo detection of Macrorhabdus ornithogaster. A total of 100 faecal and gastric mucosa samples from avian cadavers were investigated, using cytological and qPCR techniques (budgerigars, Fischer's lovebirds, red-crowned parakeets, scarlet-chested parrots, eastern rosellas, domestic canaries, zebra finches, white Java sparrow). Using qPCR, the probability of detecting positive samples of droppings was significantly higher than in the faecal smear microscopy (P < 0.01). Cytology detected the presence of Macrorhabdus ornithogaster in 34 faecal samples, whereas qPCR detected 54 positive samples. In all 46 qPCR negative faecal samples, gastric smear qPCR was performed and also yielded negative results. Gastric smear qPCR was also performed in 20 cadavers where faecal qPCR has detected the presence of Macrorhabdus ornithogaster and in all samples confirmed the positive result. This verifies the accuracy of faecal sample qPCR for intravital diagnostics. Overall, the faecal qPCR technique appears to be extremely reliable, as it made it possible to detect all infected individuals, including those with negative stool or gastric cytology. [ABSTRACT FROM AUTHOR]

Volunteer-based (i.e., citizen science) monitoring schemes constitute a basic piece for the long-term monitoring of bird populations. This work aims to determine whether we can reduce the sampling effort, in terms of number of sampling journeys per yearly campaign, of a long-term breeding bird monitoring ringing scheme in Spain. With that goal, we test to what extent a progressive decreasing number of journeys (from the original effort of seven visits in a season to four visits) will have an impact on indices of adult abundance and/or productivity. Reducing the number of visits did not affect the estimate of abundance of adults, either if we consider a full-period population change index which takes into account the numbers of the last survey year in relation to the first one in the series, or if we consider annual trends (with a yearly index which is referred to a reference value—1—fixed for the first survey year). By contrast, the estimation of productivity was severely affected by a reduction of the sampling effort. We attribute this result to the fact that juveniles were captured late in the season and, therefore, eliminating the last sampling journeys produced biased estimates. It is proposed that the program can reduce the effort from seven to six visits (i.e., one visit per fortnight from May to July) with little impact on the estimation of abundance and productivity. Additionally, the program may admit sites with a sampling effort of four visits, from May to June, useful to estimate trends on abundance of adults and their survival rates (but not on productivity). With this dual option, we expect to increase the spatial coverage of the program and the robustness and representativeness of at least two of the indices calculated through the program, since we might both increase the number of participants (i.e., sites) and the type of habitats covered. [ABSTRACT FROM AUTHOR]

Birds are among the most exploited animals due to their melodious songs and attractive plumage, but few studies explore the clandestine bird trade at local markets. To assess the bird trade in Mexico City, we recorded the number of individuals of each species for sale in three markets during two periods of 2012-2013 and 20152016. We recorded 74 bird species for sale, with a total of 20,388 individuals in 2012-2013 and 20,004 individuals in 2015-2016 of all species in the three markets. This included 11 species of native Psittaciformes whose sale is prohibited in Mexico, as well as eight internationally endangered or threatened species, and six species in CITES Appendix I prohibiting their trade. The overall number of birds for sale, and the number of non-native (-15,000 - 18,000) birds for sale, remained constant between the two periods. However, we found a significant increase in the number of individuals of native bird species for sale, from 1,892 birds in 2012-2013 to 4,506 native birds in 2015-2016. We recorded 24 species of songbirds that also increased significantly between periods as almost all songbirds were native species. Our results demonstrate that the sale of companion, ornamental and songbirds has persisted in Mexico City markets, with non-native species selling in consistently high numbers, and a significant increase in the number of native birds for sale. This indicates a high demand for singing and ornamental birds, with associated risks of introducing non-native species, and illegal trade of species at risk that affects threatened populations. [ABSTRACT FROM AUTHOR]

The aim of the work is to supplement the current data on the fauna and population of passerine birds on the Nature Reserve "Bolsherechensky", located in the Altai Territory in the lower reaches of the Bolshaya Rechka River. The territory of the preserve is typical for the Verkhneobskiy forest area. One of the primary duties of the Nature Reserve is to protect the habitats of rare and endangered bird species. However, the modern avifauna in the reserve, despite several previous reports, remains underestimated and not sufficiently studied. Our work has been carried out over the spring and summer of 2012, 2013, 2017 and 2021. The number of species was estimated based on their density obtained during the survey, and a point scale was used to describe the species. We concluded that the summer (breeding) passerine bird populations of the Nature Reserve "Bolsherechensky" consist of 12 families and 35 species, while the presence of 15 rare bird species was registered in the Reserve. Our results will enrich the data bank on the fauna and the population of passerine birds of the lower reaches of the Bolshaya Rechka River in the Nature Reserve "Bolsherechensky", which can be used to improve biodiversity conservation measures.