Spot-billed Duck Research Articles

Mitochondrial genome of the Indian spot-billed duck and its phylogenetic and conservation implications.

The Indian spot-billed duck, Anas poecilorhyncha is a large dabbling and non-migratory breeding bird. The identification and phylogenetic relationship of A. poecilorhyncha remain uncertain due to the presence of overlapping meristic characters and hybridization with closely related species. Molecular data aids when there are challenges in morphological identification. However, genetic characterization of A. poecilorhyncha has been paid less attention. Apart from their functional and physiological role, mitochondrial genome can also be used for various purposes, including species identification, phylogenetic analysis, understanding the domestication history of species etc. Therefore, the present study aimed to sequence the mitochondrial genome of A. poecilorhyncha and its closely related domestic species A. platyrhynchos (mallard duck) to understand their mitochondrial genome structure and phylogenetic relationships. The length of mitochondrial genome of A. poecilorhyncha and A. platyrhynchos was 16,608 and 16,604bp respectively. Mitochondrial genome contained 37 genes and a non-coding control region. Overall, the characteristics of mitochondrial genome of both species were found to be conserved. The phylogenetic tree exhibited seven major clades (A to G) with a high bootstrap support. Notably, the Indian A. poecilorhyncha population formed a distinct clade (C) whereas the A. poecilorhyncha that were probably sampled from China grouped along with A. zonorhyncha (clade B). Besides, one of the A. poecilorhyncha probably sampled from China was placed in the clade A, which predominantly consisted of A. platyrhynchos. It suggests that Indian A. poecilorhyncha population is genetically different from Chinese A. poecilorhyncha population. Further, it sheds light on the importance of conducting a comprehensive phylogenetic study on these species. The newly sequenced mitochondrial genome of A. poecilorhyncha and A. platyrhynchos would be useful not only to have a better understanding of the phylogeny and evolution of Anas species but also to help in the conservation of A. poecilorhyncha which is under constant threat from rapid urbanization, interspecific hybridization and other human activities.

Seed dispersal by wintering ducks in a coastal wetland of eastern China

Duck species are important vectors for seed dispersal of many plants, contributing significantly to the regeneration of wetland plant communities. However, research on the temporal changes in diet and the dynamics and differences of seed dispersal among different duck species is still limited. In this study, we analyzed the diversity of duck community and the diversity of seeds in the feces of different duck species from December to February for 2022–23 and 2023–24 in the coastal wetland of Dafeng, eastern Jiangsu Province, China. A total of 13 duck species were recorded in the four habitats, of which Spot-billed Ducks (Anas zonorhyncha) and Mallards (A. platyrhynchos) were the most abundant. The diversity and abundance of ducks vary across different habitats, and tidal flat supports the greatest diversity and abundance of ducks. We collected fecal samples from Spot-billed Ducks, Gadwalls (Mareca strepera), Mallards, and Eurasian Teals (A. crecca) in the tidal flat, from which seeds belonging to 7 families, 13 genera and 15 different plant species were obtained. There were significant differences in seed dispersal among the four duck species, which varied with the season. Gadwalls and Common Teals showed more significant diversity in seed dispersal, with their feces containing a greater variety of plant seeds, which is related to their broader dietary range and ecological adaptability. Furthermore, the seasonal variation in the number of seeds per feces reflected the availability of seeds in the habitat and the response of ducks to environmental changes, while variations in seed intake among different duck species may be associated with inter-annual weather condition changes. The results of this study will provide a new perspective for understanding the mechanisms of bird-mediated seed dispersal in coastal wetland and offer preliminary insights for the seed dispersal by Asian ducks.

River width and depth as key factors of diurnal activity energy expenditure allocation for wintering Spot-billed Ducks in the Xin'an River Basin

Rivers are important habitats for wintering waterbirds. However, they are easily influenced by natural and human activities. An important approach for waterbirds to adapt to habitats is adjusting the activity time and energy expenditure allocation of diurnal behavior. The compensatory foraging hypothesis predicts that increased energy expenditure leads to longer foraging time, which in turn increases food intake and helps maintain a constant energy balance. However, it is unclear whether human-disturbed habitats result in increased energy expenditure related to safety or foraging. In this study, the scan sample method was used to observe the diurnal behavior of the wintering Spot-billed Duck (Anas poecilorhyncha) in two rivers in the Xin'an River Basin from October 2021 to March 2022. The allocation of time and energy expenditure for activity in both normal and disturbed environments was calculated. The results showed that foraging accounted for the highest percentage of time and energy expenditure. Additionally, foraging decreased in the disturbed environment than that in the normal environment. Resting behavior showed the opposite trend, while other behaviors were similar in both environments. The total diurnal energy expenditure of ducks in the disturbed environment was greater than that in the normal environment, with decreased foraging and resting time percentage and increased behaviors related to immediate safety (swimming and alert) and comfort. These results oppose the compensatory foraging hypothesis in favor of increased security. The optimal diurnal energy expenditure model included river width and water depth, which had a positive relationship; an increase in either of these two factors resulted in an increase in energy expenditure. This study provides a better understanding of energy allocation strategies underlying the superficial time allocation of wintering waterbirds according to environmental conditions. Exploring these changes can help understand the maximum fitness of wintering waterbirds in response to nature and human influences.

Data on hunting use of waterfowl resources in Yakutia

Scientific information on waterfowl harvesting in Yakutia is mostly outdated. The lack of reliable bag data prevents the establishment of sustainable use of waterfowl resources under the conditions of massive shooting and a modified legislation base. This research aimed to collect and analyze contemporary information on the hunting take of waterfowl (Anatidae, Coot, loons, and grebes) in Yakutia. We used data from the State Hunting Registry (2017–2022) to estimate the total harvest. Species-specific shares in hunting bags were identified using digital photographs of shot birds collected from the Internet in 2015, 2017, and 2018 (around 1000 photos). The distribution and results of traditional spring hunting of scoters were studied through a survey of hunters conducted in 2015. On average, 18,400 geese and 200,000 ducks were shot during the summer-autumn season, whereas 26,600 geese and 160,500 ducks were shot during the spring season. Overall, 23 waterfowl species were identified, namely three species of geese, 17 species of ducks, Coot, Arctic Loon, and Red-necked Grebe. The autumn bag included 22 species, of which the bean goose, mallard, Eurasian wigeon, and common teal were the most abundant. Spring bags consisted of 14 species with prevailing bean geese, common teals, northern pintails, and mallards. Based on “least concern” international and national conservation status we suggest to exclude the Chinese Spot-billed Duck, Gadwall, Common Scoter and Coot from the Red Data Book of the Republic of Sakha (Yakutia) and resume their hunting use.

Characterization of avian influenza A (H4N2) viruses isolated from wild birds in Shanghai during 2019 to 2021

The H4 subtype of avian influenza viruses has been widely distributed among wild birds. During the surveillance of the avian influenza virus in Shanghai from 2019 to 2021, a total of 4,451 samples were collected from wild birds, among which 46 H4 subtypes of avian influenza viruses were identified, accounting for 7.40% of the total positive samples. The H4 subtype viruses have a wide range of hosts, including the spot-billed duck, common teal, and other wild birds in Anseriformes. Among all H4 subtypes, the most abundant are the H4N2 viruses. To clarify the genetic characteristics of H4N2 viruses, the whole genome sequences of 20 H4N2 viruses were analyzed. Phylogenetical analysis showed that all 8 genes of these viruses belonged to the Eurasian lineage and closely clustered with low pathogenic avian influenza viruses from countries along the East Asia-Australia migratory route. However, the PB1 gene of 1 H4N2 virus (NH21920) might provide its internal gene for highly pathogenic avian influenza H5N8 viruses in Korea and Japan. At least 10 genotypes were identified in these viruses, indicating that they underwent multiple complex recombination events. Our study has provided a better epidemiological understanding of the H4N2 viruses in wild birds. Considering the mutational potential, comprehensive surveillance of the H4N2 virus in both poultry and wild birds is imperative.

Characterization of a reassortant H11N9 subtype avian influenza virus isolated from spot-billed duck in China

H11N9 viruses in wild birds might have provided the NA gene of human H7N9 virus in early 2013 in China, which evolved with highly pathogenic strains in 2017 and caused severe fatalities. To investigate the prevalence and evolution of the H11N9 influenza viruses, 16,781 samples were collected and analyzed during 2016–2020. As a result, a novel strain of influenza A (H11N9) virus with several characteristics that increase virulence was isolated. This strain had reduced pathogenicity in chicken and mice and was able to replicate in mice without prior adaptation. Phylogenetic analyses showed that it was a sextuple‐reassortant virus of H11N9, H3N8, H3N6, H7N9, H9N2, and H6N8 viruses present in China, similar to the H11N9 strains in Japan and Korea during the same period. This was the H11N9 strain isolated from China most recently, which add a record to viruses in wild birds. This study identified a new H11N9 reassortant in a wild bird with key mutation contributing to virulence. Therefore, comprehensive surveillance and enhanced biosecurity precautions are particularly important for the prediction and prevention of potential pandemics resulting from reassortant viruses with continuous evolution and expanding geographic distributions.

The First Crested Duck Genome Reveals Clues to Genetic Compensation and Crest Cushion Formation

The Chinese crested (CC) duck is a unique indigenous waterfowl breed, which has a crest cushion that affects its survival rate. Therefore, the CC duck is an ideal model to investigate the genetic compensation response to maintain genetic stability. In the present study, we first generated a chromosome-level genome of CC ducks. Comparative genomics revealed that genes related to tissue repair, immune function, and tumors were under strong positive selection, indicating that these adaptive changes might enhance cancer resistance and immune response to maintain the genetic stability of CC ducks. We also assembled a Chinese spot-billed (Csp-b) duck genome, and detected the structural variations (SVs) in the genome assemblies of three ducks (i.e., CC duck, Csp-b duck, and Peking duck). Functional analysis revealed that several SVs were related to the immune system of CC ducks, further strongly suggesting that genetic compensation in the anti-tumor and immune systems supports the survival of CC ducks. Moreover, we confirmed that the CC duck originated from the mallard ducks. Finally, we revealed the physiological and genetic basis of crest traits and identified a causative mutation in TAS2R40 that leads to crest formation. Overall, the findings of this study provide new insights into the role of genetic compensation in adaptive evolution.

Avian species survey with citizen-science data in Janghang Wetland, Goyang, Republic of Korea.

Monitoring of avian populations in Janghang Wetland, Goyang, Republic of Korea (ROK) is based on citizen science (also called community-based monitoring). This monitoring data can be used to track avian density, population status and waterbird census at local, national and regional levels. The Ministry of Environment (MoE) ROK has surveyed since 1999, including Odusan Unification Tower to Ilsan Bride, which connects the cities of Gimpo and Goyang along the Han River estuary. However, it has not covered Janghang Wetland, which is located in the Han River estuary at the transboundary between the two Koreas. The Janghang Wetland is a protected wetland in the Demilitarized Zone (DMZ) between the two Koreas. In 2019, Janghang Wetland was designated as a Flyway Network Site by Goyang City and the East Asian-Australasian Flyway Partnership. This Network site is a voluntary collaboration and includes many internationally significant wetlands for waterbirds that still lack formal national protection. In addition, it was designated as a Ramsar site in 2021. The wetland currently supports wintering population of White-naped Crane (Grusvipio), species listed as vulnerable and Tundra Bean Goose (Ansercygnoides), spring-autumn migration population of Swan Goose (Ansercygnoid), species listed as vulnerable and a breeding population of Black-faced Spoonbill (Plataleaminor), species listed as endangered in summer. We provide data that the Janghang Wetland is a significant area for migration and breeding for waterbirds; and that Han River estuary is also internationally important for waterbirds during the migratory bird season. We observed 14 orders, 42 families and 132 species. The surveys also observed the critically-endangered Black-faced Spoonbill (Plataleaminor), Swan Goose (Ansercygnoides), White-naped Crane (Grusvipio), Whooper Swan (Cygnuscygnus) and Peregrine Falcon (Falcoperegrinus). We also observed the Black-faced Spoonbill, Great Egret, Little Egret, Great Cormorant, Eastern Spot-billed Duck, Pheasant and Brown-eared Bulbul at the sensor camera point and White-naped Crane, Hooded Crane, Bean Goose, White-fronted Goose, Snow Goose, Swan Goose, Great Cormorant and Eastern Spot-billed Duck at the closed-circuit television camera point from the camera-trap surveys. Based on the species recorded, the survey area is of clear importance for biodiversity conservation.

Chinese Domestic Ducks Evolved from Mallard Duck (Anas platyrhynchos) and Spot-Billed Duck (A. zonorhyncha)

China has a rich genetic resource in its 34 domestic duck breeds. In order to detect the genetic diversity and explore the origin of these indigenous duck populations, the mitochondrial DNA (mtDNA) control region was sequenced and analyzed for 208 individual ducks, including 22 domestic breeds, wild Mallards ducks, Eastern spot-billed ducks, White Muscovy ducks, and Black Muscovy ducks. The haplotype diversity (Hd) was 0.653 and the average nucleotide diversity (Pi) was 0.005, indicating moderate genetic diversity. Sixty haplotypes were detected, and the maximum-likelihood (ML) phylogenetic tree and median-joining (MJ) network were generated from the sequence analyses. In this study, haplotypes from the Mallard duck (Anas platyrhynchos) were detected in most of the Chinese domestic duck breeds. In addition, the Eastern spot-billed duck (A. zonorhyncha) H8 haplotype was detected in two duck breeds. Only two haplotypes were found in Muscovy ducks, suggesting low genetic diversity within this population. The sequence and haplotype analyses revealed that both A. platyrhynchos and A. zonorhyncha contributed to the evolution of domestic ducks in China.

Avifaunal Diversity and Abundance in the Proposed Sarasalai Mangrove Reserve, Jaffna, Sri Lanka

Mangrove ecosystems are excellent habitats for migrating and resident birds. The proposed Sarasalai mangrove reserve is located in one of the richest waterbird zones in Sri Lanka. This site has never been properly studied as a single site for its avifaunal diversity. Hence, the present study aims to find avifaunal diversity in the Sarasalai mangrove. Data collection was performed from April to December 2021. Eight permanent sampling stations were demarcated along the existing roads and were visited twice a month to collect bird abundance data. A total of 107 bird species belonging to 45 families including 58 waterbird species were recorded in the present study. Bird abundance did not significantly differ among the eight studied sites. Studied sites with the availability of water and good tree cover had the highest Shannon Diversity Index. The mangrove vegetation, with tall grasses, and the high water level were significant factors for bird abundance in some sites. Monthly bird abundance showed a notable increase during the migratory months. Among the recorded bird species, Greater Flamingos showed the highest abundance. Moreover, some rare waterbirds including Indian Spot-billed Duck and Glossy Ibis were commonly recorded. Several putative threats have been recorded during this study, namely unplanned land encroachments, bird hunting, and clearing of mangroves. Although this site has a high value in providing a healthy habitat for many wetland birds, it is yet to be declared a protected area. The lack of a clear boundary and a governing body to protect this area exacerbates its protection issues. Hence, it is proposed that immediate legal actions must be taken to declare this important migratory bird area a mangrove forest reserve.

Nest site selection and breeding ecology of Spot-billed Duck (Anas zonorhyncha) in the alpine wetland ecosystem of southwestern China

The global abundance of Spot-billed Duck (Anas zonorhyncha) has declined dramatically in recent decades. Ecological information of its wild populations, particularly regarding nest site selection, is scant. We studied the nest site selection and breeding ecology of this duck in Caohai National Nature Reserve, its southernmost breeding site in the Guizhou Province of China. The aquatic vegetation of Caohai is composed of 2 different landscapes with small patches (in Site A) or large patches (in Site B). We studied the habitat preferences of breeding Spot-billed Ducks at 3 spatial scales: landscape, patch, and nest site. In total, we surveyed 413 patches during the breeding seasons of 2014–2016 (298 in Site A and 115 in Site B). We found no nests in Site A, but surveyed 88 patches with 254 nests and 27 patches without nests in Site B. Unlike the open-cup nests known from other breeding localities, the nests of the Spot-billed Duck in Caohai were dome-like structures with a lateral entrance. Patches with nests were significantly larger than patches without nests in total area, circumference, and shape index. In Site B, a negative binomial regression showed that the number of nests was positively correlated with sedge vegetation within the patch area. The reduced model from a binary logistic regression indicated that the total vegetation cover and the distance to bank had positive impacts on nest site selection of this duck in Caohai, but water depth had a negative influence. Our study suggests good concealment is a necessity for the Spot-billed Duck to construct nests in Caohai. Our survey using infrared cameras in 2021 did not record male parents participating in incubation (n = 47 cameras). The mean mass of eggs (46.91 ± 0.36 g) and clutch size (8.48 ± 0.08 eggs) values were lower than those reported for the Xianghai National Nature Reserve, a breeding stronghold for the Spot-billed Duck in northeastern China. The nest success rate in Caohai (nests where at least 1 egg hatched) was 40.4% (n = 47 nests) and the hatching success rate was 91.4% (n = 134 eggs from 19 successful nests). Maintaining the emergent hydrophyte vegetation is the primary means to conserve the nesting habitat of the Spot-billed Duck in Caohai and it is necessary to strictly enforce the law against human disturbance.

Airborne Avian Influenza Virus in Ambient Air in the Winter Habitats of Migratory Birds.

Outbreaks of avian influenza virus (AIV) have raised public concerns recently. Airborne AIV has been evaluated in live poultry markets and case farms; however, no study has discussed airborne AIV in ambient air in the winter habitats of migratory birds. Therefore, this study aimed to evaluate airborne AIV, specifically H5, H7, and H9, in a critical winter habitat of migratory birds and assess the factors influencing airborne AIV transmission in ambient air to provide novel insights into the epidemiology of avian influenza. A total of 357 ambient air samples were collected in the Aogu Wetland, Taiwan, Republic of China, between October 2017 and December 2019 and analyzed using quantitative real-time polymerase chain reaction. The effects of environmental factors including air pollutants, meteorological factors, and the species of the observed migratory birds on the concentration of airborne AIV were also analyzed. To our knowledge, this is the first study to investigate the relationship between airborne AIV in ambient air and the influence factors in the winter habitats of migratory birds, demonstrating the benefits of environmental sampling for infectious disease epidemiology. The positive rate of airborne H7 (12%) was higher than that of H5 (8%) and H9 (10%). The daily mean temperature and daily maximum temperature had a significant negative correlation with influenza A, H7, and H9. Cold air masses and bird migration were significantly associated with airborne H9 and H7, respectively. In addition, we observed a significant correlation between AIV and the number of pintails, common teals, Indian spot-billed ducks, northern shovelers, Eurasian wigeons, tufted ducks, pied avocets, black-faced spoonbills, and great cormorants. In conclusion, we demonstrated the potential for alternative surveillance approaches (monitoring bird species) as an indicator for influenza-related risks and identified cold air masses and the presence of specific bird species as potential drivers of the presence and/or the airborne concentration of AIV.

Assessment of the spatiotemporal risk of avian influenza between waterfowl and poultry farms during the annual cycle: A spatial prediction study focused on seasonal distribution changes in resident waterfowl in South Korea.

Previous studies and efforts to prevent and manage avian influenza (AI) outbreaks have mainly focused on the wintering season. However, outbreaks of AI have been reported in the summer, including the breeding season of waterfowl. Additionally, the spatial distribution of waterfowl can easily change during the annual cycle due to their life-cycle traits and the presence of both migrants and residents in the population. Thus, we assessed the spatiotemporal variation in AI exposure risk in poultry due to spatial distribution changes in three duck species included in both major residents and wintering migrants in South Korea, the mandarin, mallard and spot-billed duck, during wintering (October-March), breeding (April-June) and whole annual seasons. To estimate seasonal ecological niche variations among the three duck species, we applied pairwise ecological niche analysis using the Pianka index. Subsequently, seasonal distribution models were projected by overlaying the monthly ranges estimated by the maximum entropy model. Finally, we overlaid each seasonal distribution range onto a poultry distribution map of South Korea. We found that the mandarin had less niche overlap with the mallard and spot-billed duck during the wintering season than during the breeding season, whereas the mallard had less niche overlap with the mandarin and spot-billed duck during the breeding season than during the wintering season. Breeding and annual distribution ranges of the mandarin and spot-billed duck, but not the mallard, were similar or even wider than their wintering ranges. Similarly, the mandarin and spot-billed duck showed more extensive overlap proportions between poultry and their distributional ranges during both the breeding and annual seasons than during the wintering season. These results suggest that potential AI exposure in poultry can occur more widely in the summer than in winter, depending on sympatry with the host duck species. Future studies considering the population density and variable pathogenicity of AI are required.

Isolation and Genomic Characterization of Avian Reovirus From Wild Birds in South Korea.

Avian reoviruses (ARVs) cause severe arthritis, tenosynovitis, pericarditis, and depressed growth in chickens, and these conditions have become increasingly frequent in recent years. Studies on the role of wild birds in the epidemiology of ARVs are insufficient. This study provides information about currently circulating ARVs in wild birds by gene detection using diagnostic RT-PCR, virus isolation, and genomic characterization. In this study, we isolated and identified 10 ARV isolates from 7,390 wild birds' fecal samples, including migratory bird species (bean goose, Eurasian teal, Indian spot-billed duck, and mallard duck) from 2015 to 2019 in South Korea. On comparing the amino acid sequences of the σC-encoding gene, most isolates, except A18-13, shared higher sequence similarity with the commercial vaccine isolate S1133 and Chinese isolates. However, the A18-13 isolate is similar to live attenuated vaccine av-S1133 and vaccine break isolates (SD09-1, LN09-1, and GX110116). For the p10- and p17-encoding genes, all isolates have identical fusion associated small transmembrane (FAST) protein and nuclear localization signal (SNL) motif to chicken-origin ARVs. Phylogenetic analysis of the amino acid sequences of the σC-encoding gene revealed that all isolates were belonged to genotypic cluster I. For the p10- and p17-encoding genes, the nucleotide sequences of all isolates indicated close relationship with commercial vaccine isolate S1133 and Chinese isolates. For the σNS-encoding gene, the nucleotide sequences of all isolates indicated close relationship with the Californian chicken-origin isolate K1600657 and belonged to chicken-origin ARV cluster. Our data indicates that wild birds ARVs were derived from the chicken farms. This finding suggests that wild birds serve as natural carriers of such viruses for domestic poultry.

Community structure and behavioral characteristics of wintering dabbling ducks (<i>Anas</i>) at Lake Shengjin, the middle and lower reaches of the Yangtze River floodplain

升金湖是长江中下游地区典型的浅水通江湖泊，是东亚-澳大利西亚候鸟迁徙路线上水鸟重要的越冬地. 2017年11月-2018年3月，以该湖泊越冬鸭属(Anas)鸟类为研究对象，对其在芦苇湿地、芡实塘、退耕还湿和水生植被恢复湿地4种湿地生境中的群落结构、行为特征及其环境影响因素进行了研究. 结果表明，升金湖分布有10种越冬鸭属鸟类，斑嘴鸭(Anas poecilorhyncha)、绿翅鸭(A. crecca)和绿头鸭(A. platyrhynchos)为该属鸟类群落的优势种. 鸭属鸟类群落在越冬前期种类和数量最多，在整个越冬期，鸭属鸟类在芦苇湿地中种数、数量、密度和多样性指数最高. 在水生植物盖度高、人为活动弱的芦苇湿地，鸭类的主要行为是休息；在食物资源丰富、人为活动强的芡实塘和退耕还湿湿地，其主要行为是觅食和警戒. 鸭属鸟类群落种数、数量、密度和多样性指数与湿地的面积、水域面积、水生植物盖度呈正相关，与干扰度和水深呈负相关. 觅食时间与气温和沉水植物的盖度呈正相关，与水深和干扰度呈负相关，警戒时间与干扰度呈正相关，与挺水植物的盖度呈负相关. 各种恢复类型的湿地生境成为越冬鸭属鸟类的重要栖息地，因此恢复多种湿地栖息地对于越冬水鸟的保护具有重要意义.;Lake Shengjin, a typical shallow lake connecting Yangtze River in the middle and lower Yangtze floodplain, is an important wintering habitat for waterbirds on the East Asian-Australasian Flyway. From November 2017 to March of 2018, ccommunity structure, behavioral characteristics of wintering dabbling duck (Anas) and the dominant environmental factors in reed wetland, foxnut ponds, farmland-returning wetland and aquatic vegetation restoration wetland at Lake Shengjin were studied. The results show that there were 10 species of dabbling duck at Lake Shengjin, in which spot-billed duck (Anas poecilorhyncha), common teal (A. crecca) and mallard (A. platyrhynchos) were dominant species in the community. In early winter the species and numbers of dabbling duck reached maximum. During the whole overwintering period, the species, number, density and diversity of dabbling ducks reached the peak in reed wetland. The main behavior of dabbing ducks was taking rest in reed wetlands with large-coverage aquatic plants and weak human activity, and was foraging and vigilance in foxnut ponds and farmland-returning dampness with abundant food and strong human activities. The number, flock size, density, diversity and foraging behaviors of dabbling duck community were positively correlated with the wetland area, water area, aquatic plant coverage, while negatively correlated with disturbance degree and water depth. The foraging time of dabbling duck has positive relationship with temperature and coverage degree of submerged plants, and negative relationship with water depth and disturbance. The vigilance time of dabbling ducks was positively related with disturbance and negatively related with the coverage degree of water plants. Various types of restored wetlands have become important habitats for wintering dabbling ducks, therefore, restoring a variety of wetland habitats is of great importance to the protection of wintering waterbirds.

Home range of mallard (Anas platyrhynchos) and spot-billed duck (Anas poecilorhyncha) during the 2014/15 highly pathogenic avian influenza epidemics in the Republic of Korea

Home range of mallard (Anas platyrhynchos) and spot-billed duck (Anas poecilorhyncha) during the 2014/15 highly pathogenic avian influenza epidemics in the Republic of Korea

Decline in the Population of Korean Wintering Waterbirds after Use of Bale Silage and Completion of a Massive River Engineering Project

The Geum River, Republic of Korea, is an important wintering site for waterbirds that migrate along the East-Asian Australasian Flyway. It has recently experienced two major changes in environmental conditions as a result of increased use of bale silage (wrapping and sealing forage crops with plastic bags during harvest) beginning in 2007, and the Four Major Rivers Restoration Project (FMRRP) in 2011 to deepen and widen the major rivers in Republic of Korea. To examine these effects on wintering waterbirds, we monitored changes in wintering waterbird abundance in the downstream and upstream regions of Geum River. Wintering waterbirds in the downstream region were reduced by 67% after use of bale silage compared to before bale silage. The FMRRP changed the habitat structure, deepening and widening the river, followed by a substantial decline in overall wintering waterbirds in both regions (38% in the downstream and 51% in the upstream). Mallard (Anas platyrhynchos) and Spot-billed Duck (A. poecilorhyncha) populations showed the most decrease in numbers. However, Common Mergansers (Mergus merganser), that fish in deep water, increased over the same time. The effects of such changes in habitat conditions are not temporary, elucidating the need for monitoring and conservation programs for wintering waterbirds.

Spatiotemporal risk assessment for avian influenza outbreak based on the dynamics of habitat suitability for wild birds.

Highly pathogenic avian influenza (HPAI) has predominantly damaged the poultry industry worldwide. The fundamental prevention and control strategy for HPAI includes early detection and timely intervention enforcement through a systematic surveillance system for wild birds based on the ecological understanding of the dynamics of wild birds' movements. Our study aimed to develop a spatiotemporal risk assessment model for avian influenza (AI) infection in wild birds to empower surveillance information for a contingency strategy. For this purpose, first, we predicted the monthly habitat suitability of seven waterfowl species, using 227,671 Global Positioning System (GPS) tracking records of 562 birds from 2014 to 2018 in the Republic of Korea (ROK). Then, that predicted habitat suitability and 421 coordinates of AI detection sites in wild birds were used to build the risk assessment model. Subsequently, we compared the monthly predicted risk of avian influenza virus (AIv) identification in wild birds between case and non-case poultry farms with HPAI H5N6 outbreak in the ROK between 2016 and 2017. The results reported considerable variation of monthly habitat suitability of seven waterfowls and the impact of predicting AI occurrences in wild birds. The high habitat suitability for spot-billed ducks (contribution rate in November=40.9%) and mallards (contribution rate in January=34.3%) significantly contributed to predicting the average risk of AIv identification in wild birds, with high predictive performance [the monthly mean of area under the curve (AUC)=0.978]. Moreover, our model showed that the averaged risk of identification AI in wild birds was significantly higher in HPAI infected premises, with infected domestic duck holdings exhibiting a significantly higher risk than the chicken farms in November. This study suggests that animal health authority establishes a risk-based HPAI surveillance system grounded on the ecological nature of wild birds to improve the effectiveness of prevention and preparedness of emerging epidemics.

Positive selection of skeleton-related genes during duck domestication revealed by whole genome sequencing

BackgroundDomestication alters several phenotypic, neurological, and physiological traits in domestic animals compared to those in their wild ancestors. Domestic ducks originated from mallards, and some studies have shown that spot-billed ducks may have also made minor genetic contributions to domestication. Compared with the two ancestral species, domestic ducks generally differ in body size and bone morphology. In this study, we performed both genomic and transcriptomic analyses to identify candidate genes for elucidating the genetic mechanisms underlying phenotypic variation.MethodsIn this study, the duck genome data from eight domestic breeds and two wild species were collected to study the genetic changes during domestication. And the transcriptome data of different tissues from wild ducks and seven domestic ducks were used to reveal the expression difference between wild and domestic ducks.ResultsUsing fixation index (Fst) algorithm and transcriptome data, we found that the genes related to skeletal development had high Fst values in wild and domestic breeds, and the differentially expressed genes were mainly enriched in the ossification pathway. Our data strongly suggest that the skeletal systems of domestic ducks were changed to adapt to artificial selection for larger sizes. In addition, by combining the genome and transcriptome data, we found that some Fst candidate genes exhibited different expression patterns, and these genes were found to be involved in digestive, immune, and metabolic functions.ConclusionsA wide range of phenotypic differences exists between domestic and wild ducks. Through both genome and transcriptome analyses, we found that genes related to the skeletal system in domestic ducks were strongly selected. Our findings provide new insight into duck domestication and selection effects during the domestication.

Whole-genome resequencing provides insights into the population structure and domestication signatures of ducks in eastern China

BackgroundDuck is an ancient domesticated animal with high economic value, used for its meat, eggs, and feathers. However, the origin of indigenous Chinese ducks remains elusive. To address this question, we performed whole-genome resequencing to first explore the genetic relationship among variants of these domestic ducks with their potential wild ancestors in eastern China, as well as understand how the their genomes were shaped by different natural and artificial selective pressures.ResultsHere, we report the resequencing of 60 ducks from Chinese spot-billed ducks (Anas zonorhyncha), mallards (Anas platyrhnchos), Fenghua ducks, Shaoxing ducks, Shanma ducks and Cherry Valley Pekin ducks of eastern China (ten from each population) at an average effective sequencing depth of ~ 6× per individual. The results of population and demographic analysis revealed a deep phylogenetic split between wild (Chinese spot-billed ducks and mallards) and domestic ducks. By applying selective sweep analysis, we identified that several candidate genes, important pathways and GO categories associated with artificial selection were functionally related to cellular adhesion, type 2 diabetes, lipid metabolism, the cell cycle, liver cell proliferation, and muscle functioning in domestic ducks.ConclusionGenetic structure analysis showed a close genetic relationship of Chinese spot-billed ducks and mallards, which supported that Chinese spot-billed ducks contributed to the breeding of domestic ducks. During the long history of artificial selection, domestic ducks have developed a complex biological adaptation to captivity.