Spring Migration Research Articles

Identifying seasonal differences in migration characteristics of Oriental white stork (Ciconia boyciana) through satellite tracking and remote sensing

Migratory species interact with different ecosystems in different regions during migration, making them more environmentally sensitive and therefore more vulnerable to extinction. Long migration routes and limited conservation resources desire clear identification of conservation priorities to improve the allocation efficiency of conservation resources. Clarifying the spatio-temporal heterogeneity of the utilization intensity during migration is an effective way to guide the conservation areas and priority. 12 Oriental White Storks (Ciconia boyciana), listed as an “endangered” species by the IUCN, were equipped with satellite-tracking loggers to record their hourly location throughout the year. Then, combined with remote sensing and dynamic Brownian Bridge Movement Model (dBBMM), characteristics and differences between spring and autumn migration were identified and compared. Our findings revealed that: (1) the Bohai Rim has always been the core stopover area for the Storks’ spring and autumn migration, but the utilization intensity has spatial differences; (2) differences in habitat selection resulted in differences in the Storks’ spatial distribution, thus affecting the efficiency of existing conservation systems; (3) the shift of habitat from natural wetlands to artificial surfaces calls for the development of eco-friendly land use mode; (4) the development of satellite tracking, remote sensing, and advanced data analysis methods have greatly facilitated movement ecology, even though they are still under development.

A cold high-pressure system over North China hinders the southward migration of Mythimna separata in autumn

BackgroundIn warm regions or seasons of the year, the planetary boundary layer is occupied by a huge variety and quantity of insects, but the southward migration of insects (in East Asia) in autumn is still poorly understood.MethodsWe collated daily catches of the oriental armyworm (Mythimna separata) moth from 20 searchlight traps from 2014 to 2017 in China. In order to explore the autumn migratory connectivity of M. separata in East China, we analyzed the autumn climate and simulated the autumn migration process of moths.ResultsThe results confirmed that northward moth migration in spring and summer under the East Asian monsoon system can bring rapid population growth. However, slow southerly wind (blowing towards the north) prevailed over the major summer breeding area in North China (33°–40° N) due to a cold high-pressure system located there, and this severely disrupts the autumn ‘return’ migration of this pest. Less than 8% of moths from the summer breeding area successfully migrated back to their winter-breeding region, resulting in a sharp decline of the population abundance in autumn. As northerly winds (blowing towards the south) predominate at the eastern periphery of a high-pressure system, the westward movement of the high-pressure system leads to more northerlies over North China, increasing the numbers of moths migrating southward successfully. Therefore, an outbreak year of M. separata larvae was associated with a more westward position of the high-pressure system during the previous autumn.ConclusionThese results indicate that the southward migration in autumn is crucial for sustaining pest populations of M. separata, and the position of the cold high-pressure system in September is a key environmental driver of the population size in the next year. This study indicates that the autumn migration of insects in East China is more complex than previously recognized, and that the meteorological conditions in autumn are an important driver of migratory insects’ seasonal and interannual population dynamics.

Activity patterns throughout the annual cycle in a long-distance migratory songbird, the red-backed shrike Lanius collurio

BackgroundLong-distance migratory birds undergo complex annual cycles during which they must adjust their behaviour according to the needs and conditions encountered throughout the year. Yet, variation in activity throughout the entire annual cycle has rarely been studied in wild migratory birds.MethodsWe used multisensor data loggers to evaluate the patterns of activity throughout the complete annual cycle of a long-distance migratory bird, the red-backed shrike Lanius collurio. Accelerometer data was used to identify life-history stages and to estimate levels of activity during various phases of the annual cycle. In this study, we analysed the variation in daytime activity along the annual cycle and between migratory and non-migratory days.ResultsThe birds’ daytime activity varied throughout the annual cycle while night-time activity was almost exclusively restricted to migratory flights. The highest daytime activity levels were observed during the breeding season, while it remained low during autumn migration and the winter period. Daytime activity differed between sexes during the breeding period, when the males showed the highest level in activity. During migratory periods, both sexes exhibited a higher daytime activity in spring compared to autumn migration, being particularly high in the final migratory leg towards the breeding ground. The birds showed a lower daytime activity on migratory days (days when a migratory flight took place during the succeeding night) than on non-migratory days during both migratory seasons.ConclusionsActivity measured during daytime results from a combination of several behaviours, and a high daytime activity during spring migration and the breeding period is possibly reflecting particularly energy-demanding periods in the annual cycle of migratory birds. The use of multisensor data loggers to track annual activity provides us with a full annual perspective on variation in activity in long-distance migratory species, an essential approach for understanding possible critical life-history stages and migration ecology.

Potential Role of Intensive Bird Growing during Outbreaks of Viral Zoonosis in Ukraine, Russian Federation, Kazakhstan and Belarus (on the Model Viruses Highly Pathogenic Influenza and Newcastle Diseases): Systematic Review

The paper highlights the impact of two cross-border poultry infections with zoonotic potential (avian flu and Newcastle disease) on the functioning of industrial poultry farms in the former Soviet Union counties (Ukraine, Russia, Belarus, Kazakhstan), where the poultry industry is fairly well-developed. Despite the permanent vaccination of poultry against Newcastle disease in industrial poultry farming, the disease still affects individual farms in Ukraine, the Russian Federation, and Kazakhstan. In case of outbreaks, the Russian Federation and Kazakhstan use inactivated influenza vaccines. In Ukraine, for almost 20 years, outbreaks of influenza have been confirmed mainly on individual farms, and one outbreak of highly pathogenic influenza was reported on an industrial poultry farm in 2020. In the Russian Federation, highly pathogenic influenza occurs on industrial poultry farms more often. In Russia, seven industrial poultry enterprises were affected by influenza in 2016-2017, and eight in 2018. Infection of poultry with influenza virus on poultry factory farms is an indication of shortcomings in compliance with biosecurity measures. Influenza and Newcastle disease are always likely to occur in the countries in question, as wild birds migrate through their territory, and they are a reservoir of pathogens, therefore outbreaks are often associated with spring and autumn migrations of wild birds. In all of said countries, a large number of poultry is kept by individual households, where basic biosecurity, sanitation and preventive vaccination measures are not applied. This component is often crucial in bringing viral infections such as influenza and Newcastle disease on large poultry farms. As a result, the virus is brought onto poultry farms by synanthropic birds, humans, transport, feed, etc.

Rapid shifts in migration routes and breeding latitude in North American bluebirds

AbstractSpatial and temporal shifts in the migratory patterns of birds have become more frequent as climate change and habitat alteration continue to impact ecosystems and the species dependent on them. In this study, we used eBird community science data collected over ten years to examine potential changes in the migratory patterns of three North American bluebird species: eastern (Sialia sialis), western (Sialia mexicana), and mountain (Sialia currucoides) bluebirds. Community science datasets such as those provided through eBird are a valuable tool for examining population‐level processes, as such data are often costly and time‐consuming to collect through other approaches (e.g., directly tracking individuals). Using generalized additive models, we produced smoothed migration paths for all three species over each season from 2009 to 2018. We asked whether there were changes over this 10‐year period in the timing of spring and fall migration and migration speed, and the population centroids during breeding and migration. In contrast to many species that are experiencing poleward shifts in their distributions, the population centroids during the breeding period of all three bluebird species appear to have shifted southward over the past decade. Perhaps most surprisingly, we also detected strong longitudinal shifts in the population centroids during migration in eastern and western bluebirds, with both species shifting toward the center of the continent. Despite these changes in migratory routes and breeding distributions, we detected no change in the migratory timing or speed of any of the species. Our analysis indicates that bluebirds are rapidly altering the pattern of their migration, likely in response to changing environmental conditions, but not always in the direction predicted.

Tens of thousands of migrating hoverflies found dead on a strandline in the South of France

Abstract Knowledge on insect migration is scattered, and we are only starting to grasp the extent and ecological impacts of their massive seasonal bioflows. Hoverflies (Diptera: Syrphidae) are one group of insects which partake in these long‐distance journeys, which are thought to have important ecological consequences including pollination, biocontrol and nutrient transfer. Yet, few sightings of mass spring migration have been documented so far. Here, we report observations of tens of thousands of dead insects on a strandline in the South of France in mid‐May 2022. Hoverflies represented 77% of all dead flying insects found on the strandline and most individuals belonged to the species Episyrphus balteatus and Eupeodes corollae, which are species known to exhibit migratory behaviour. We assume that strong winds or a localised storm were the cause behind their stranding. Putative flight origins for these insects are north‐eastern Catalonia or the Balearic Islands. This rarely documented observation enabled us to highlight the scope of hoverfly migration in spring and to discuss some of the challenges they face along their migratory route.

Trends in Rail Migration Arrival and Departure Times Using Long-Term Citizen Science Data from Mississippi, USA

Little is known of rail migration ecology, consequently limiting efforts to effectively conserve rail populations. Therefore, we investigated changes in the migratory arrival/departure dates for Virginia Rails (Rallus limicola), King Rails (Rallus elegans) and Sora (Porzana carolina) north of Ocean Springs, Mississippi. Using citizen science data collected over the last 25 years, we inspected summarized data for patterns of primary arrival and departure windows indicated by first or last observations of each species at the lagoons, respectively, alongside 10th/90th quantiles that controlled for outliers (i.e., early arrivals, late departures). Regression models found no differences in spring migration departures for any species. In fall migration we found a difference only in Virginia Rail arrivals, which became later over time. King Rail arrived in autumn first in mid-September (September 22nd) followed by Sora (October 5th) and Virginia Rails (October 21st). In spring migration, Virginia Rails departed first (March 19th), then King Rails (March 24th), and Sora (April 20th). Trends for King Rails may have been skewed by some individuals having non-migratory behavior. Despite limitations, citizen science efforts were useful for an initial investigation of rail migration ecology, and future applications could be used to identify and assess factors affecting migration timing (e.g., climate change, habitat availability, weather shifts).

Plants dispersed by a non‐frugivorous migrant change throughout the annual cycle

AbstractAimMigratory waterfowl are important endozoochory vectors for a range of plants lacking fleshy fruits. Our aim was to study the critical question of how endozoochory rates change throughout the annual cycle, and how this relates to plant life‐form and phenology.LocationLake Velence, Hungary.Time period2017–2018.Major taxa studiedMallard (Anas platyrhynchos), Angiospermae, Charophyta.MethodsWe studied waterfowl endozoochory, quantifying seeds and other diaspores dispersed by mallards by collecting faecal samples monthly (ntotal = 670) at a Hungarian lake. We tested the germinability of all seeds recovered from the faecal samples.Main conclusionsWe extracted 5,760 seeds representing 35 plant taxa from mallard faecal samples, and 40% of these seeds germinated successfully following gut passage. We found major differences between seasons in the species composition of the seeds recovered. The peak in species diversity and in abundance of terrestrial seeds coincided with the spring migration of mallards. Importantly, endozoochory was only strongly synchronized with seed production in submerged, but not in emergent or terrestrial plants, illustrating the potential for endozoochory of seeds ingested from the soil seed bank. Overall, our results suggest that endozoochory by migratory waterfowl is a strong and underestimated driver of plant distributions, and is likely to facilitate plant range shifts under climate change, and after introduction of alien species.

Bird–building collisions increase with weather conditions that favor nocturnal migration and with inclement and changing weather

AbstractCollisions with building windows are a top bird mortality source, but few studies have evaluated how bird–window collisions are influenced by weather. By monitoring collisions daily at 21 buildings in Minneapolis, Minnesota, over 4 migration seasons, we show that weather influences numbers of window collisions of nocturnal migrants in spring and fall, indicating that collisions may be forecastable based on weather conditions. Collisions increased with weather favoring migration, such as consecutive nights of south wind in spring and even short periods of north wind in fall. We also found evidence that spring and fall collisions increase with weather changes that impede migration, such as changes from fair conditions and tailwinds early in the night to headwinds near sunrise. Our study suggests complex weather effects never before considered in the context of bird collisions, including possible time lag effects of conditions 2–3 nights before collisions occur, effects of multi-day sequences of conditions, and interactions between conditions at different times of night. More research is needed to determine if the accuracy of weather-based collision prediction systems improves by integrating such nuances and to clarify mechanisms through which these complex effects operate, such as influences of weather on migration intensity and collision avoidance behavior. Weather-based forecasts may allow refinement of collision mitigation approaches (e.g., reducing building lighting on certain nights or using temporary glass coverings or treatments). However, because challenges remain to communicating such temporally targeted actions and implementing them in a timely manner, other bird-friendly practices (e.g., season-long lighting reduction and permanent glass treatments) should continue to be prioritized.

Linking migration and microbiota at a major stopover site in a long-distance avian migrant

Migration is one of the most physical and energetically demanding periods in an individual bird’s life. The composition of the bird’s gut or cloacal microbiota can temporarily change during migration, likely due to differences in diets, habitats and other environmental conditions experienced en route. However, how physiological condition, migratory patterns, and other drivers interact to affect microbiota composition of migratory birds is still unclear. We sampled the cloacal bacterial microbiota of a long-distance migrant, the steppe buzzard (Buteo buteo vulpinus), at an important spring stopover bottleneck in Eilat, Israel, after crossing the ca. 1800 km Sahara Desert. We examined whether diversity and composition of the cloacal microbiota varied with body condition, sex, movement patterns (i.e., arrival time and migration distance), and survival. Early arrival to Eilat was associated with better body condition, longer post-Eilat spring migration distance, higher microbial α-diversity, and differences in microbiota composition. Specifically, early arrivals had higher abundance of the phylum Synergistota and five genera, including Jonquetella and Peptococcus, whereas the phylum Proteobacteria and genus Escherichia-Shigella (as well as three other genera) were more abundant in later arrivals. While the differences in α-diversity and Escherichia-Shigella seem to be mainly driven by body condition, other compositional differences associated with arrival date could be indicators of longer migratory journeys (e.g., pre-fueling at wintering grounds or stopover habitats along the way) or migratory performance. No significant differences were found between the microbiota of surviving and non-surviving individuals. Overall, our results indicate that variation in steppe buzzard microbiota is linked to variation in migratory patterns (i.e., capture/arrival date) and body condition, highlighting the importance of sampling the microbiota of GPS-tracked individuals on multiple occasions along their migration routes to gain a more detailed understanding of the links between migration, microbiota, and health in birds.

Age-related changes in migratory behaviour within the first annual cycle of a passerine bird.

First time migrants (juveniles hereafter) of many species migrate without specific knowledge of non-breeding locations, but experience may aid adults in timing and route decisions because they can migrate more efficiently to their previous non-breeding sites. Consequently, we expect a transition to more efficient migratory behaviour with age, but when and how this happens is little known. We used light-level geolocator data from Cyprus wheatears Oenanthe cypriaca to compare migration timing and route directness between juveniles and adults, and repeatability of their timing and non-breeding locations. We predicted that juveniles would depart and arrive later than adults for both autumn and spring migration; that duration of migration would be greater for juveniles; that routes taken by juveniles would be less direct than those for adults; and that autumn and spring departure timing, and non-breeding locations, would be more repeatable for adults between two years than for juveniles between their first and subsequent migration. We found that juveniles departed significantly later than adults in autumn but there was no difference in arrival timing, and although spring departure timings did not differ, juveniles arrived on the breeding grounds later than adults. Nevertheless, we found no significant age-related difference in the duration of migration in autumn or spring. Yet, juvenile migrations were less direct than those of adults in autumn, but not spring. We found evidence that spring departure timing and non-breeding locations were repeatable for adults but not juveniles. Our findings show that age-related changes in migratory behaviour begin to occur during the first annual cycle demonstrating the potential for early adaptation to environmental variability within an individual’s life.

Automating sandhill crane counts from nocturnal thermal aerial imagery using deep learning

AbstractPopulation monitoring is essential to management and conservation efforts for migratory birds, but traditional low‐altitude aerial surveys with human observers are plagued by individual observer bias and risk to flight crews. Aerial surveys that use remote sensing can reduce bias and risk, but manual counting of wildlife in imagery is laborious and may be cost‐prohibitive. Therefore, automated methods for counting are critical to cost‐efficient application of remote sensing for wildlife surveys covering large areas. We conducted nocturnal surveys of sandhill cranes (Antigone canadensis) during spring migration in the Central Platte River Valley of Nebraska, USA, using midwave thermal infrared sensors. We developed a framework for automated counting of sandhill cranes from thermal imagery using deep learning, assessed and compared the performance of two automated counting models, and quantified the effect of spatial resolution on counting accuracy. Aerial thermal imagery data were collected in March 2018 and 2021; 40 images were analyzed. We applied two deep learning models: an object detection approach, Faster R‐CNN and a recently developed pixel‐density estimation approach, ASPDNet. Model performance was determined using data independent of the training imagery. The effect of spatial resolution was quantified with a beta regression on relative error. Our results showed model accuracy of 9% mean percent error for ASPDNet and 18% for Faster R‐CNN. Most error was related to the undercounting of sandhill cranes. ASPDNet had <50% of the error of Faster R‐CNN as measured by mean percent error, root‐mean‐squared error and mean absolute error. Spatial resolution affected accuracy of both models, with error rate increasing with coarser resolution, particularly with Faster R‐CNN. Deep learning models, particularly pixel‐density estimators, can accurately automate counting of migratory birds in a dense, aggregate setting such as nocturnal roosting sites.

A Long-Term Vision for an Ecologically Sound Platte River

The Platte River extends about 310 mi (499 km) from North Platte, Nebraska, to its terminus at the Missouri River confluence near Plattsmouth, Nebraska. The Platte River Valley is a continentally significant ecosystem that serves as a major stopover for migratory waterbirds in the Central Flyway including the endangered Whooping Crane (Grus americana) and >1 million Sandhill Cranes (Antigone canadensis) at the peak of spring migration. However, the Platte River Valley also supports a great diversity of avifauna including grassland breeding birds, native stream fish, vascular plants, herpetofauna, mammals, pollinators, and aquatic macroinvertebrates. Despite ongoing conservation efforts since the mid-1970s the ecosystem remains largely conservation dependent and an increasing number of species across taxa are being considered at risk of regional extirpation or outright extinction. However, given the attention provided to conservation in the Platte River Valley and the need to maintain ecologically functional stopover sites in the Central Flyway, there is a great opportunity to create a resilient refugium for biodiversity conservation in the central Great Plains. To that end we convened a working group of >18 individuals representing >9 organizations including representatives from non-profit conservation organizations, universities, and state and federal natural resource agencies to develop a long-term vision for an ecologically sound Platte River Valley (PRV). We met in groups of varying size for >170 hours throughout a more than 3-year period and developed conservation priorities and objectives using a landscape design process. Landscape design is an interdisciplinary conservation planning process that incorporates components of landscape ecology and social dimensions of natural resources with the explicit intention of improving conservation implementation.

Migration and energetics model predicts delayed migration and likely starvation in oiled waterbirds

Oil spills can inflict mortality and injury on bird populations; many of these deaths involve starvation resulting from thermoregulatory costs incurred by oiling of birds’ feathers. However, the fates and responses of sublethally oiled birds are poorly known. Due to this knowledge gap and the potential for birds to die far from the spill site, resource risk and injury assessors need tools to make informed estimates for delayed deaths and lost reproductive capacity in these birds. Focusing on the thermoregulatory cost of oiled feathers, we present a model addressing one facet of the effects of sublethal oiling on birds. Using mallard-like ducks as a model organism, we combined values from previous laboratory studies of oiled birds with a modified version of an existing temperature-influenced avian migration energetics model. Using this model, we examined the potential effects of oiling on general migration patterns, changes in energetic gains required to compensate for oiling, and starvation. We assessed all metrics across multiple oiling severities; we assessed starvation across both oiling severity and body condition. Median estimates for delays in spring migration were one to two months for trace and lightly oiled birds, and we predicted arrested spring migration in moderately oiled birds. Median estimates of required increases in energetic gains to offset costs of increased thermoregulation ranged from 20.3% to 88.6% depending on severity of oiling. We predicted starvation within four weeks for most combinations of oiling severity and body condition at the median predicted minimum wintering temperature of unoiled birds (-4.9°C). However, at the average winter temperature of the southernmost model latitude (10.8°C), we predicted only moderately oiled birds in less-than-excellent body condition had the potential to starve within a four-week time frame. Due to the potential for even trace oiling to delay spring migration and decrease body condition, the thermoregulatory costs of sublethal oiling during spring migration could reduce a bird's reproductive capacity. Future research integrating this initial energetics-based model into a spatially explicit, population scale migration model could provide additional insight into the potential effects of sublethal oiling on reproduction and survival. Such an integrated model could strengthen risk predictions and injury assessments for birds subjected to sublethal oiling.

Blood Metabolites and Profiling Stored Adipose Tissue Reveal the Differential Migratory Strategies of Eurasian Reed and Sedge Warblers

The overall speed of bird migration is limited by the amount of fuel stores acquired during the initial phases of migration. The ability to mobilize fat is crucial for migratory birds that can exhibit different migratory strategies. Birds mobilize triglycerides during nocturnal flight thus increasing circulating fatty acids and glycerol to meet the metabolic demands of flight. Eurasian Reed (Acrocephalus scirpaceus) and Sedge (Acrocephalus schoenobaenus) Warblers were captured at Portuguese stopover sites during spring and autumn migration. These species were selected based on their different migration strategies and dietary preferences during migration. Blood metabolites and fat composition were analyzed to determine their nutritional states. Sedge Warblers had higher blood triglyceride and glycerol levels during post-flight fasting than in non-fasting periods. Furthermore, Sedge Warblers had higher triglyceride and glycerol levels than Eurasian Reed Warblers in both post-flight fasting and non-fasting condition. The differences found may reflect distinct approaches in re-feeding activity (e.g., feeding intensely) associated with the number of stopovers during migratory cycle. Dietary preferences affect the fat composition available for oxidation during long-term exercise in migratory flight. Nuclear magnetic resonance analysis of subcutaneous fat composition revealed that Sedge Warblers presented higher levels of polyunsaturated fatty acid levels than Eurasian Reed Warblers. The distinct lipidic profiles observed and differences in feeding ecology may explain the different migration strategies of these species. Overall and despite their ecological similarity, our study species showed pronounced differences in blood metabolites levels and subcutaneous fatty acids composition, likely attributed to the migratory strategy and foraging preferences during their migratory cycle.

Migratory hoverflies orientate north during spring migration.

Migratory hoverflies are long-range migrants that, in the Northern Hemisphere, move seasonally to higher latitudes in the spring and lower latitudes in the autumn. The preferred migratory direction of hoverflies in the autumn has been the subject of radar and flight simulator studies, while spring migration has proved to be more difficult to characterize owing to a lack of ground observations. Consequently, the preferred migratory direction during spring has only been inferred from entomological radar studies and patterns of local abundance, and currently lacks ground confirmation. Here, during a springtime arrival of migratory insects onto the Isles of Scilly and mainland Cornwall, UK, we provide ground proof that spring hoverfly migrants have an innate northward preference. Captured migratory hoverflies displayed northward vanishing bearings when released under sunny conditions under both favourable wind and zero-wind conditions. In addition, and unlike autumn migrants, spring individuals were also able to orientate when the sun was obscured. Analysis of winds suggests an origin for insects arriving on the Isles of Scilly as being in western France. These findings of spring migration routes and preferred migration directions are likely to extend to the diverse set of insects found within the western European migratory assemblage.

A magnetic pulse does not affect free-flight navigation behaviour of a medium-distance songbird migrant in spring.

Current evidence suggests that migratory animals extract map information from the geomagnetic field for true navigation. The sensory basis underlying this feat is elusive, but presumably involves magnetic particles. A common experimental manipulation procedure consists of pre-treating animals with a magnetic pulse, with the aim of re-magnetising particles to alter the internal representation of the external field prior to a navigation task. Although pulsing provoked deflected bearings in caged songbirds, analogous studies with free-flying songbirds yielded inconsistent results. Here, we pulsed European robins (Erithacus rubecula) at an offshore stopover site during spring migration and monitored their free-flight behaviour with a regional-scale network of radio-receiving stations. We found no pulse effect on departure probability, nocturnal departure timing departure direction or consistency of flight direction. This suggests either no use of the geomagnetic map by our birds, or that magnetic pulses do not affect the sensory system underlying geomagnetic map detection.

Direct and Indirect Role of Migratory Birds in Spreading CCHFV and WNV: A Multidisciplinary Study on Three Stop-Over Islands in Italy

The annual movements of migratory birds can contribute to the spread of African ticks and tick-borne pathogens of potential public health concern across Europe. The aim of the study was to investigate their role in the possible introduction of African ticks and tick-borne pathogens into European countries during spring migration. A total of 2344 ticks were collected during three spring seasons from 1079 birds captured on three Italian stop-over islands during their northbound migration. Once identified, each tick was tested by RT-PCR for the presence of Crimean-Congo hemorrhagic fever (CCHFV), West Nile (WNV), and Usutu (USUV) viruses. Moreover, carcasses of birds found dead were collected and tested for the possible presence of WNV and USUV. Results confirmed a higher contribution of trans-Saharan migrants compared to intra-Palearctic ones and the prevalence of African tick species in the sample. CCHFV was detected for the second time in Italy in a Hyalomma rufipes, and WNV was found in two ticks of the same genus, all carried by trans-Saharan birds. WNV lineage 1 was also found in the organs of a Garden warbler. These results confirm the role of migratory birds in carrying African ticks, as well as viruses of zoonotic importance, from Africa into Europe.

Light-level geolocation reveals the short-distance non-breeding movements and distribution of tufted puffins throughout the Northeast Pacific Ocean

Comprehensive assessments of cumulative impacts to seabirds have been hindered by an incomplete understanding of temporal and spatial patterns in marine habitat use, particularly during the non-breeding season when seabirds can range widely across the global ocean. Alcids are an important component of the meso-predator biodiversity of the North Pacific Ocean, yet the non-breeding movement ecology and distribution for many of the Pacific Auk species remain poorly quantified. Recent and projected declines for historically robust populations of tufted puffin (Fratercula cirrhata) in Alaska highlight the importance of resolving aspects of the species’ non-breeding ecology, especially the pelagic phenology and distribution. We used light-level geolocation to quantify the annual at-sea distribution of tufted puffins between a major Gulf of Alaska nesting colony (Middleton Island) and heretofore unknown migration routes and wintering areas. Geolocator data from 42 complete migration routes of reproductive adult tufted puffins collected primarily between 2018-2020 revealed that both males and females were short-distance migrants, wintering on average 616 km from their breeding colony. Tufted puffins departed the breeding grounds in early September. Males made fewer stops and arrived earlier to wintering areas than females, however the arrival date to the wintering area was later in 2019 compared to 2018. Males took 30.5 ± 16.7 (± standard deviation) days in 2018 and 30.8 ± 24.6 days in 2019 to arrive at wintering areas. Conversely, females took 36.1 ± 16.8 days in 2018 and 59.8 ± 17.3 days in 2019 to arrive at wintering areas. Adult tufted puffins wintered primarily in the deep offshore waters of the eastern Gulf of Alaska and partially in the adjacent Northeast Pacific Ocean over a period of 151.9 days ± 31.6 with spring migrations starting by late March. Males and females showed consistent spatial distributions within seasons, especially during winter. Tufted puffins shifted southwards throughout the non-breeding season, similar to other Atlantic and Northeast Pacific alcids. Our study provides important information on the at-sea non-breeding phenology and distribution of tufted puffins, which can inform risk assessments for the species including vulnerability to spatially and temporally explicit marine pollution, disease, fisheries by-catch, and ocean-climate variability.

Effect of sex on the gut microbiota characteristics of passerine migratory birds.

The gut microbiota, considered the “invisible organ” in the host animal, has been extensively studied recently. However, knowledge about the gut microbiota characteristics of passerine migratory birds during migration is limited. This study investigated the gut microbiota characteristics of three dominant migratory bird species (namely orange-flanked bluetail Tarsiger cyanurus, yellow-throated bunting Emberiza elegans, and black-faced bunting Emberiza spodocephala) in the same niche during spring migration and whether they were bird sex-specific. The compositions of gut microbiota species in these three migratory bird species and their male and female individuals were found to be similar. The main bacterial phyla were Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes, and the main genera were Lactobacillus, Acinetobacter, Rickettsiella, and Mycobacterium; however, their relative abundance was different. Moreover, some potential pathogens and beneficial bacteria were found in all the three bird species. Alpha diversity analysis showed that in T. cyanurus, the richness and diversity of the gut microbiota were higher in male individuals than in female individuals, while the opposite was true for E. elegans and E. spodocephala. The alpha diversity analysis showed significant differences between male and female individuals of E. elegans (p < 0.05). The beta diversity analysis also revealed that the gut microbial community structure differed significantly between the male and female individuals of the three migratory bird species.