Larus Ridibundus Research Articles

Future of birds nesting on river islands in the conditions of hydrological variability caused by climate change

The mew gull (Larus canus), little tern (Sternula albifrons) and black-headed gull (Chroicocephalus ridibundus) are threatened in Poland by the loss of breeding habitats due to changes in the hydrological regime of rivers and the frequency and length of inundation. Analysis of daily flows generated from the SWAT model allowed us to obtain the values of hydrological characteristics expressed as Indicators of Hydrological Alteration (IHA) and find the relationship with collected data on nesting success on islands and sandbanks in the Middle Vistula from 2004 until 2018. For each bird species, a set of adjusted IHA was calculated for future scenarios (2021-2050 and 2071-2100). The projections were prepared on the basis of EURO-CORDEX and contain two scenarios of changes in greenhouse gas concentrations: RCP4.5 and RCP8.5. Catastrophic breeding seasons quantification was carried out to assess the number of years that will have unsuitable hydrological breeding conditions in the projected climate change. The mew gull noted the lowest nesting success (during 2004-2018) but it seems that hydrology is not the principal factor causing it. This species will experience an increase in high flows due to climate change in the far future scenarios. The black-headed gull is projected not to be affected by an increase in the percentage of catastrophic breeding seasons due to climate change. The little tern seems to be the most affected by projected climate change due to an increase in high flows and, in consequence, an increasing percentage of catastrophic breeding seasons. The results confirmed the importance of hydrologic change for avian nesting success.

Avian influenza overview December 2022 - March 2023.

Between 3 December 2022 and 1 March 2023 highly pathogenic avian influenza (HPAI) A(H5N1) virus, clade 2.3.4.4b, was reported in Europe in domestic (522) and wild (1,138) birds over 24 countries. An unexpected number of HPAI virus detections in sea birds were observed, mainly in gull species and particularly in black-headed gulls (large mortality events were observed in France, Belgium, the Netherlands, and Italy). The close genetic relationship among viruses collected from black-headed gulls suggests a southward spread of the virus. Moreover, the genetic analyses indicate that the virus persisted in Europe in residential wild birds during and after the summer months. Although the virus retained a preferential binding for avian-like receptors, several mutations associated to increased zoonotic potential were detected. The risk of HPAI virus infection for poultry due to the virus circulating in black-headed gulls and other gull species might increase during the coming months, as breeding bird colonies move inland with possible overlap with poultry production areas. Worldwide, HPAI A(H5N1) virus continued to spread southward in the Americas, from Mexico to southern Chile. The Peruvian pelican was the most frequently reported infected species with thousands of deaths being reported. The reporting of HPAI A(H5N1) in mammals also continued probably linked to feeding on infected wild birds. In Peru, a mass mortality event of sea lions was observed in January and February 2023. Since October 2022, six A(H5N1) detections in humans were reported from Cambodia (a family cluster with 2 people, clade 2.3.2.1c), China (2, clade 2.3.4.4b), Ecuador (1, clade 2.3.4.4b), and Vietnam (1, unspecified clade), as well as two A(H5N6) human infections from China. The risk of infection with currently circulating avian H5 influenza viruses of clade 2.3.4.4b in Europe is assessed as low for the general population in the EU/EEA, and low to moderate for occupationally or otherwise exposed people.

Factors Affecting Colony Size and Breeding Parameters of Eared Grebe (Podiceps nigricollis) in Carp Ponds

Understanding important factors for breeding Eared Grebes (Podiceps nigricollis) is essential for its conservation. We aimed to study the impact of some factors on nests and breeding success in this species in fishponds (S Poland). Number of Eared Grebe nests were counted on particular carp ponds. Pond size, vegetation cover, number of nests in colonies of associated gull or tern species, and age of stocked common carp (Cyprinus carpio) were determined for all ponds with nests. We also investigated the relationship between nest size, material used to construct them and clutch size. Number of Eared Grebe nests positively correlated with number of breeding pairs of associated colonial species (terns or gulls). Selection of the breeding site by the Eared Grebe can be explained by appropriate nest protection by large colonies of associated species (Whiskered Tern Chlidonias hybrida and Black-headed Gull Chroicocephalus ridibundus). Nest size was not related to clutch size. A negative relationship between breeding success and number of nests of Eared Grebe was found. Food is a not limiting factor for the Eared Grebe on fishponds with extensive production, and presumably other factors such as weather conditions may explain the low breeding success of this species.

Diversity and prevalence of Salmonella spp. in gulls caught at a landfill, Zagreb, Croatia

Gulls are a group of seabirds distributed worldwide that are an important reservoir of Salmonella spp. Salmonellosis is the second most commonly reported gastrointestinal infection in humans, and understanding the role wild birds have in spreading Salmonella can help to improve the health of humans and domestic animals. The mobility and migration capacity of gulls makes them an interesting group for research given their potential role in spreading pathogens. This paper presents the diversity and prevalence of Salmonella spp. in different gull species caught at a landfill in Zagreb in the winter months over a nine-year period from 2014-2022. In total, 1083 cloacal swabs were sampled from six gull species: Black-headed Gull (Larus ridibundus), Yellow-legged Gull (L. michahellis), Caspian Gull (L. cachinnans), Common Gull (L. canus), Lesser Black-back Gull (L. fuscus) and Herring Gull (L. argentatus). The prevalence of Salmonella was 5.82%, and 16 Salmonella serotypes were identified; S. Typhimurium had the highest prevalence (47.62%) followed by S. Enteritidis (12.69%) and S. Infantis (9.52%). To date, 82 Salmonella serotypes have been isolated in research on gulls in Europe, with S. Typhimurium as the most common, followed by S. Agona and S. Enteritidis. In this study, we found three serotypes not previously reported in gulls, S. Yalding, S. Reading and one with the antigenic formula O:17; H:z10; H:e,n,x,z15 (IIIb).

New records of ectoparasites from the Black-headed Gull, Chroicocephalus ridibundus (Linnaeus, 1766) in Algeria

The Black-headed Gull, Chroicocephalus ridibundus Linnaeus, 1766, is a migratory bird that winters along the entire Algerian coast and is considered a protected species. In this study, we report the first-ever collection and identification of ectoparasites from Black-headed Gulls in the province of Boumerdes, Algeria. From October and November of 2020 and 2021, a total of 45 live Black-headed Gulls were captured using modified Bal-chatri traps and examined for the presence of ectoparasites. The results revealed a total of 3537 ectoparasite specimens, 264 of which belonged to Phthiraptera and 3273 to Acari. Within Phthiraptera, two species from the suborder Ischnocera were identified: Saemundssonia lari Fabricius, 1780, with a prevalence of 62.22%, and Quadraceps punctatus Burmeister, 1838, with a prevalence of 93.33%. Additionally, one species from the suborder Amblycera, Actornithophilus piceus lari Packard, 1870, was found with a prevalence of 86.66% and the lowest mean intensity with the value of 0.90. As for Acari, Zachvatkinia larica Mironov, 1989, was the most common with a prevalence of 71.11% and the highest mean intensity value of 102.28. Notably, all the recorded parasite species found in the Black-headed Gull in this study are reported in Algeria and in North Africa for the first time. The Pearson’s correlation test indicated a significant difference in parasite infestation of the gull population (r = 0.716; p = 0.046).

Мониторинг солнечного орла в национальном парке «Хвалынский» (Саратовская область, Россия)

Мониторинг солнечного орла в национальном парке «Хвалынский» (Саратовская область, Россия)

Black‐headed gulls synchronize vigilance with their nearest neighbor irrespective of the neighbor's relative position

AbstractBehavioral synchronization refers to actions conducted simultaneously by two or more individuals at the same place. Through behavioral synchronization, animals may increase social cohesion of their groups or achieve antipredator and foraging benefits. We examined whether black‐headed gulls (Chroicocephalus ridibundus) synchronized vigilance with their nearest neighbors and whether synchronization was affected by the neighbor's relative position. We predicted that (1) the synchronization of vigilance is less likely when neighbors are positioned behind focal individuals, i.e., within the blind sector of their visual field, and that (2) birds may show preference for copying vigilance when neighbors are situated at one side due to known laterality in avian eye use for antipredator vigilance. Data were obtained for 46 pairs of individuals—focal gulls and their nearest neighbors—through the observation of video‐recorded material. Gulls significantly synchronized vigilance with their nearest neighbors irrespective of the neighbor's relative spatial position—the odds that the focal individual would scan its environment were increased almost three times if the nearest neighbor was also vigilant. Contrary to our predictions, however, we did not find evidence that synchronization of vigilance in gulls was dependent on their nearest neighbor's relative position, which could be due to several reasons: (i) gulls may pay attention not only to their nearest neighbors but also to more distant ones and/or (ii) gulls may have reacted to some cues other than visual, such as alarm sounds. Although the mechanism of synchronization in gulls remains unknown, by being vigilant at the same time as other group members, the gulls may achieve additional antipredator benefits.

Seabirds as Biomonitors of Mercury Bioavailability in the Venice Lagoon

Seabirds accumulate mercury (Hg) due to their long-life span together with their high trophic position. A Hg monitoring in Venice's Lagoon using three seabird species occupying different trophic habitat (Thalasseus sandvicensis, Ichthyaetus melanocephalus, and Chroicocephalus ridibundus) confirmed that fledgelings might effectively be used as sentinels of Hg bioavailability. The significant differences in Hg residues in feathers observed among the species highlighted a possible differential exposure due to different diets, with C. ridibundus accumulating more Hg than the other species. Average residues in feathers were not above the threshold associated with adverse effects on birds (5mg kg- 1). Nevertheless, a large part of the C. ridibundus individuals (58%) exceeded the adverse effect level, underlining the need for strengthening Hg monitoring. Seabirds indeed may provide relevant insight on Hg transfer in food webs and a better picture of the hazards to men when bird species forage on species exploited for human consumption.

Efficacy of created and restored nesting sites for the conservation of colonial Laridae in the South of France.

By rapidly modifying key habitat components, habitat restoration is at risk of producing attractive cues for animals without providing habitats of sufficient quality. As such, individual fitness components, such as reproduction, could be reduced and restored habitats could become ecological traps. This risk notably appears by using artificial constructions in restoration projects, yet few studies have evaluated their efficacy in a robust way. We investigated this by analyzing 154 islets that were created or restored to improve the conservation status of 7 colonial Laridae species in the South of France. From 2007 to 2016, we compared occupancy dynamics and breeding parameters of these species between the restored sites and 846 unmanaged nesting sites. We also explored species' preference for different nesting site characteristics and their respective effect on breeding parameters. Restored nesting sites were 2-9 times as attractive as unmanaged sites for all species except the Black-headed Gull (Chroicocephalus ridibundus). Colonization probability was up to 100 times higher in sites already used by other species the previous year and increased with distance to the shore until >0.2 when distance was over 250m. Abandonment probability was 29-70% lower when breeding was successful the previous year in all species except the Sandwich Tern (Thalasseus sandvicensis). Productivity and breeding success probability were 2 times higher on managed sites. Distance from the shore was an important attractive characteristic of artificial nesting sites in all species. Other nesting site characteristics had species-specific effects on colonization, abandonment, and breeding success. Our results indicate that managed nesting sites are successful conservation tools for colonial Laridae in the Mediterranean and do not act as ecological traps. Our study showed that testing the ecological trap hypothesis is a robust way to evaluate the success of restoration projects of breeding habitats.

Genetic relatedness, virulence, and drug susceptibility of Campylobacter isolated from water and wild birds.

This study aimed to identify the characteristics of Campylobacter isolated from wild birds (Black-headed gulls Chroicocephalus ridibundus and Great tits Parus major) and collect surface water samples (from rivers, ponds, ornamental lakes, freshwater beaches). Research material included 33 Campylobacter isolates. All the strains were isolated by different monitoring and surveillance plans. The prevalence of selected genes (flaA, cadF, iam, cdtB, wlaN, sodB, tet0) encoding virulence factors and resistance among Campylobacter spp. was assessed by the PCR method. The genetic similarities of isolates were determined by Pulsed-Field Gel Electrophoresis (PFGE). The susceptibility of Campylobacter isolates to clinically important antimicrobials: erythromycin, tetracycline, and ciprofloxacin, previously assessed by E-test, was presented in the form of drug susceptibility profiles depending on the origin of the isolates. The cadF, flaA, cdtB, and sodB genes exhibited the highest detection rate. Statistically significant differences between the presence of wlaN virulence genes were noted among different species of the isolates. No genetically identical isolates were found. The most numerous antibiotic susceptibility profile included strains susceptible to all antibiotics studied (profile A-33.3%). The second most common were the tetracycline - and ciprofloxacin-resistant (profile B-27.2%), and tetracycline-resistant profile (C-24.2%) respectively. The study revealed the virulent properties of Campylobacter isolated from water samples, and wild birds, and high resistance rates to tetracycline, and fluoroquinolones. The lack of genetic relatedness among strains isolated from water, and birds may indicate other sources of surface water contamination with Campylobacter bacteria than birds. The presence of Campylobacter spp. in wild birds could also have other environmental origins.

Comparison of drone vs. ground survey monitoring of hatching success in the black-headed gull (Chroicocephalus ridibundus)

Comparison of drone vs. ground survey monitoring of hatching success in the black-headed gull (Chroicocephalus ridibundus)

Behavioral plasticity mediates adaptation to changes in food provisioning following the COVID-19 lockdown in black-headed gulls (Larus ridibundus)

The 2020 COVID-19 lockdown provides an opportunity to assess how the anthropause affected the behavior of birds. Black-headed gulls (Larus ridibundus) wintering at Dianchi Lake (Yunnan Province, southwestern China) prefer to forage on easily accessible human-provided food at various sites along the lake. Following the closure of the lake because of the pandemic, synthetic food was provided at a single location. We expected that the home range size and distribution of gulls would change in response to these changes in food provisioning. A total of 91 gulls were tagged with satellite transmitters in November 2018 and March 2019, and their movements were tracked during the winter months. We analyzed their home range size and spatial distribution in four periods, SCP2019, SOP2019, SCP2020, and SOP2020 (Scenic Opening/Closing Period in 2019/2020), and the difference between SOP2019 and SCP2019 was used as the control group. The eutrophication level in the wintering periods “Nov. 2018–Apr. 2019” and “Oct. 2019–Apr. 2020” was determined using the Normalized Difference Vegetation Index (NDVI), and the coverage ratio of algal blooms and NDVI were used as indicators of the amount of naturally available food. The home range sizes of gulls were reduced in SCP2020 compared with SOP2019, SCP2019, and SOP2020. The gulls were most abundant in the 600–900 m buffer zone and least abundant in the 0–300 m buffer zone in SCP2019; they were most abundant in the 0–300 m buffer zone and least abundant in the 900–2000 m buffer zone in SCP2020. These patterns were consistent with variation in the NDVI and the coverage ratio of algal blooms among buffer zones. Changes in wintering behaviors in SCP2020 relative to other periods suggested that gulls modified their behavior following anthropause-related changes in the distribution and provisioning of food. Our findings provide insights into the role of behavioral plasticity in mediating adaptation to changes in human activities in birds.

Urban Birds as Antimicrobial Resistance Sentinels: White Storks Showed Higher Multidrug-Resistant Escherichia coli Levels Than Seagulls in Central Spain.

Simple SummaryAntimicrobial resistance (AMR) has become a major health challenge of the 21st century. Several studies confirm the potential role of wildlife as sentinel for pathogens surveillance. Moreover, the presence of AMR bacteria in the wildlife can be considered as a good indicator of anthropization level on the ecosystem. The fast increase in AMR worldwide has been enhanced by several factors as globalization and migration. The study of antimicrobial resistance in wild birds is of great importance, as they can travel hundreds of kilometers and disseminate pathogens and AMR across different regions or even continents. The aim of this study was to compare the level of AMR in three bird species: white stork (Ciconia ciconia), lesser black-backed gull (Larus fuscus) and black-headed gull (Chroicocephalus ridibundus). For the analysis, 17 antibiotics from the most representative classes were tested by disk-diffusion method. Results showed 63.2% of seagulls and 31.6% of white storks as carriers of antimicrobial-resistant Escherichia coli, and from all of them, 38.9% were considered multi-drug resistant. Betalactamics, quinolones and tetracyclines were the antibiotic classes with the highest rate of AMR.The presence of AMR bacteria in the human–animal–environmental interface is a clear example of the One Health medicine. Several studies evidence the presence of resistant bacteria in wildlife, which can be used as a good indicator of anthropization level on the ecosystem. The fast increase in AMR in the environment in the last decade has been led by several factors as globalization and migration. Migratory birds can travel hundreds of kilometers and disseminate pathogens and AMR through different regions or even continents. The aim of this study was to compare the level of AMR in three migratory bird species: Ciconia ciconia, Larus fuscus and Chroicocephalus ridibundus. For this purpose, commensal Escherichia coli has been considered a useful indicator for AMR studies. After E. coli isolation from individual cloacal swabs, antimicrobial susceptibility tests were performed by the disk-diffusion method, including 17 different antibiotics. A total of 63.2% of gulls had resistant strains, in contrast to 31.6% of white storks. Out of all the resistant strains, 38.9% were considered multi-drug resistant (50% of white storks and 30% of seagulls). The antibiotic classes with the highest rate of AMR were betalactamics, quinolones and tetracyclines, the most commonly used antibiotic in human and veterinary medicine in Spain.

Multidrug-Resistant High-Risk Escherichia coli and Klebsiella pneumoniae Clonal Lineages Occur in Black-Headed Gulls from Two Conservation Islands in Germany.

Multidrug-resistant (MDR) Enterobacterales, including extended-spectrum β-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae, not only emerge in healthcare settings but also in other habitats, such as livestock and wildlife. The spread of these pathogens, which often combine resistance with high-level virulence, is a growing problem, as infections have become increasingly difficult to treat. Here, we investigated the occurrence of ESBL-producing E. coli and K. pneumoniae in fecal samples from two black-headed gull colonies breeding on two nature conservation islands in Western Pomerania, Germany. In addition to cloacal samples from adult birds (n = 211) and their nestlings (n = 99) during the 2021 breeding season, collective fecal samples (n = 29) were obtained. All samples were screened for ESBL producers, which were then subjected to whole-genome sequencing. We found a total of 12 ESBL-producing E. coli and K. pneumoniae consisting of 11 E. coli and 1 K. pneumoniae, and including the international high-risk E. coli sequence types (ST)131, ST38, and ST58. Eight of the investigated strains had a MDR genotype and carried a large repertoire of virulence-associated genes, including the pap operon, which is important for urinary tract infections. In addition, we identified many genes associated with adherence, biofilm formation, iron uptake, and toxin production. Finally, our analysis revealed the close phylogenetic relationship of ST38 strains with genomes originating from human sources, underlining their zoonotic and pathogenic character. This study highlights the importance of the One Health approach, and thus the interdependence between human and animal health and their surrounding environment.

Occurrence of rats and their impacts on colonial waterbirds in a Danish fjord

Human development around the globe has led to great expansion of the Brown Rat (Rattus norvegicus), which has implications for local wildlife and especially ground-breeding birds. In this study, we analyse the colonisation and persistence of rats on small islets important to breeding waterbirds in a Danish fjord, and investigate the effect of rat presence on the number of breeding pairs of eight waterbird species. The islets had an annual rat colonisation probability of 6% and an annual rat population persistence rate of 65% (equalling an annual population survival rate of 62% when adjusting for re-colonisations upon extinctions). Contrary to our hypotheses, rat colonisation and persistence was uncorrelated with islet size, distance from the mainland and the presence of shrub cover. Rat presence had a significant negative effect on the number of breeding pairs of four waterbird species, including Avocet (Recurvirostra avosetta, reduced to 30% compared to years without rats), Black-headed Gull (Chroicocephalus ridibundus, reduced to 45%) and Common Tern (Sterna hirundo, reduced to 52%). The smaller bird species in particular seemed to be affected by the presence of rats, and control efforts aimed at reducing rat presence on important breeding bird islets may consequently have a positive effect on the occurrence and breeding success of these species. We found no evidence of birds acting on a memory of where rats had been present in the previous year, and further research is needed to investigate the precise mechanisms behind the recorded negative effects in the contemporary year, i.e. how do prospecting as well as settled breeders detect and behaviourally respond to the presence of rats.

Contrasting haemoparasite prevalence in larid species with divergent ecological niches and migration patterns.

Haemoparasites represent a diverse group of vector-borne parasites that infect a wide range of vertebrate hosts. In birds, haemoparasite infection rates may be associated with various ecological and life history traits, including habitat choice, colony size and migration distance. Here, we molecularly assessed the prevalence of 3 main haemoparasite genera (Plasmodium, Haemoproteus and Leucocytozoon) in 2 bird species with different habitat preferences and migratory behaviour: black-headed gulls (Chroicocephalus ridibundus) and common terns (Sterna hirundo). We found that gulls showed a much higher prevalence and diversity of Plasmodium or Haemoproteus (ca. 60% of individuals infected) than terns (zero prevalence). The prevalence of Leucocytozoon was low in both species (<3%). The differences in haemoparasite prevalences may be primarily driven by varying vector encounter rate resulting from different habitat preferences, as black-headed gulls mainly use vector-rich vegetated freshwater habitats, whereas common terns often use vector-poor coastal and brackish habitats. Since common terns migrate further than black-headed gulls, our results did not provide support for an association between haemoparasite prevalence and migratory distance. In gulls, we found a negative association between colony size and infection rates, suggestive of an ideal despotic distribution, and phylogenetic analyses of detected haemoparasite lineages provided evidence for higher host specificity in Haemoproteus than Plasmodium. Our results suggest that the preference for coastal areas and less vegetated habitats in terns may reduce haemoparasite infection rates compared to other larids, regardless of their migratory distance, emphasizing the role of ecological niches in parasite exposure.

Long-term observation of the egg and chick size in the nests of Larus ichthyaetus in Lake Chany, Russia

This data set describes the long-term observation and morphological study of the eggs of the great black-headed gull Larus ichthyaetus in the gull nesting colonies on the islands of Lake Chany. Lake Chany is located in the Baraba forest-steppe of the West Siberian Plain, Russia, between the Ob and Irtish rivers. Lake Chany is protected by the Ramsar Convention on the Wetlands of International Importance, indicating that the lake is an important site for migratory birds, including L. ichthyaetus. This dataset contains the size and fate of all eggs, as well as the size of hatched chicks in 1164 observed L. ichthyaetus nests from 1993 to 2003.

Ecological aspects of the nesting life of the black-necked grebe (&lt;i&gt;Podiceps nigricollis&lt;/i&gt; C.L. Brehm) in the forest-steppe zone of the Trans-Urals

The black-necked grebe (Podiceps nigricollis C.L. Brehm) is a nesting, migratory bird species, the number of which in the Southern Urals reaches 12 thousand individuals. From an ecological point of view, the named bird species belongs to aquatic birds and prefers aquatic and semiaquatic habitats. Being a waterfowl, the black-necked grebe has a complex of diving adaptations and is characterized as a specialized waterfowl. The literature analysis has proved that the knowledge of the ecological aspects of the nesting life of the black-necked grebe is insufficient. The nesting period of the annual life cycle was studied on the Kurlady and Smolino lakes located in the forest-steppe zone of the Trans-Urals. The average date of birds arrival at the nesting area according to 19882013 data is 19 April. The choice of breeding site leads to the fact that black-necked grebes form colonies in stagnant water bodies or with a slow flow of water. The water is fresh or brackish, with a certain pattern of overgrowth of vegetation and depth in the area where the nests are located. The presence of nests of black-headed gulls (Larus ridibundus L.) plays a special role in choosing a place to build a nest. Black-necked grebes and black-headed gulls form polyspecific colonial settlements. The laying of the first egg is carried out by the black-necked grebe in an unfinished nest, floating on the water and having a flat shape. At the stage of the appearance of the first egg in the nest, the elimination of eggs occurs, which can reach 44,1% (the biological center of the colony, 1989). On the periphery of the colonial settlement, the percentage of dead clutches is significantly higher, which can be caused by unfavorable biotic and abiotic relationships. Nests of black-necked grebes are completed from the moment the first egg is laid until the laying is completed. At a statistically significant level, the diameter of the nest and tray, the height of the nest, and the depth of the tray increase. The nest with completed masonry has a truncated-conical shape with a cup-shaped tray. According to long-term observations, the average value of the completed clutch is 3,8 eggs per nest. The reproduction in the composition of a polyspecific colony is accompanied by the establishment of biocoenotic relationships. The manifestation of topical, phoric and factory relationships, which can lead to individual and group elimination, has been established.

Characterization of Deltacoronavirus in Black-Headed Gulls (Chroicocephalus ridibundus) in South China Indicating Frequent Interspecies Transmission of the Virus in Birds.

Deltacoronavirus (DCoV) is a genus of coronavirus (CoV) commonly found in avian and swine, but some DCoVs are capable of infecting humans, which causes the concern about interspecies transmission of DCoVs. Thus, monitoring the existence of DCoVs in animals near communities is of great importance for epidemic prevention. Black-headed gulls (Chroicocephalus ridibundus) are common migratory birds inhabiting in most urban and rural wetlands of Yunnan Province, China, which is a typical habitat for black-headed gulls to overwinter. Whether Yunnan black-headed gulls carry CoV has never been determined. In this study, we identified three strains of DCoVs in fecal samples of Yunnan black-headed gulls by reverse-transcriptional PCR and sequenced their whole genomes. Genomic analysis revealed that these three strains shared genomic identity of more than 99%, thus named DCoV HNU4-1, HNU4-2, and HNU4-3; their NSP12 showed high similarity of amino acid sequence to the homologs of falcon coronavirus UAE-HKU27 (HKU27), houbara coronavirus UAE-HKU28 (HKU28), and pigeon coronavirus UAE-HKU29 (HKU29). Since both HKU28 and HKU29 were found in Dubai, there might be cross-border transmission of these avian DCoVs through specific routes. Further coevolutionary analysis supported this speculation that HNU4 (or its ancestors) in black-headed gulls originated from HKU28 (or its homologous strain) in houbara, which was interspecies transmission between two different avian orders. In addition, interspecies transmission of DCoV, from houbara to falcon, pigeon and white-eye, from sparrow to common-magpie, and quail and mammal including porcine and Asian leopard cat, from munia to magpie-robin, was predicted. This is the first report of black-headed gull DCoV in Asia which was highly homolog to other avian DCoVs, and the very “active” host-switching events in DCoV were predicted, which provides important reference for the study of spread and transmission of DCoVs.

Nonrandom pattern of vigilance by preening black-headed gulls

Abstract Classic models of vigilance assume instantaneous and sequential randomness in the scanning process, implying negative exponential distribution of interscan durations and no interdependence among successive interscans. We examined whether vigilance pattern by preening black-headed gulls, Chroicocephalus ridibundus, meets these assumptions. Out of 54 behavioural sequences, 50 departed from the expected negative exponential distribution, whereas the focal interscan duration was significantly affected by the interaction of the preceding scan and the interscan interval. These results reveal departures from randomness in the scanning process by gulls, which may be a consequence of the hunting strategies of their predators or due to the trade-off between the needs for feather maintenance and antipredator vigilance.