Anser Cygnoides Research Articles

Comparative Analyses of Production Performance, Meat Quality, and Gut Microbial Composition between Two Chinese Goose Breeds.

Simple SummaryPoultry is one of the most frequently consumed meats in the world and plays an important role in the daily life of people. Goose meat is consumed by consumers because it contains a relatively high proportion of polyunsaturated fatty acids. Meat quality traits, production performance, and cecal microbiota diversity in two goose breeds (Zi goose and Xianghai flying goose) were evaluated in this study. Understanding these aspects not only provides a reference for the exploration of the relationship between the cecal microbiota and production performance but also guidelines for the human consumption of healthy poultry meat.Goose meat is consumed by consumers because it contains a relatively high proportion of polyunsaturated fatty acids (PUFAs). This study was conducted to explore the main differences in production performance, breast meat quality traits, and cecal microbiota compositions between the Zi goose (ZG) and Xianghai flying goose (FG). The production performance and breast meat quality trait analyses showed that compared with the ZG, the FG had a higher right breast muscle index, ileum villi height/crypt depth ratio (VH/CD), and cecum fermentation rate (higher short-chain fatty acid (SFCA) concentration); a lower abdominal fat index; a higher proportion of PUFAs; and a lower shear force. Spearman’s correlation coefficients between the cecal microbiota composition and production performance indexes suggested that the genus Faecalibacterium was positively associated with production performance; in contrast, the genus Candidatus Saccharimonas was negatively correlated with production performance; moreover, the Ruminococcus torques group, Parasutterella, and Methanobrevibacter were negatively related to the VH/CD. Taken together, in this particular trial, FG had better production performance, healthier meat quality traits, and better intestinal digestion and absorption capacities than ZG. These results not only provide a useful data reference for the production of healthy geese for human consumption but can also help guide the utilization of goose breed resources.

Mitochondrial dysfunction in follicles is associated with broodiness in Zhedong white goose

Zhedong white goose (Anser cygnoides) is one of the most important domesticated avian species and of high economic value in China. It has strong broody behavior, which leads to shortened egg-laying cycle, thus negatively impacting goose farming. In our previous studies, a link was established between reactive oxygen species (ROS) originated from mitochondrial activity and broodiness in geese. However, the role of mitochondria in the regulation of broodiness in geese remained unexplored. Herein, the transition from large white follicles to small yellow follicles was restrained in geese at the broody stage. Moreover, the frequency of abnormal mitochondria was increased in granulosa cells of broody follicles. Furthermore, mitochondrial dysfunction in granulosa cells of geese follicles is possibly regulated by mitochondria-related proteins including autophagy- and apoptosis-related proteins. Our results suggest that increased dysfunctional mitochondria in granulosa cells in the follicles of Zhedong white geese are involved in the regulation of broodiness. The present study contributes to expand the knowledge on goose broodiness and provides an important reference for the control of broodiness in avian species.

Genome-wide association study for reproduction-related traits in Chinese domestic goose

ABSTRACT 1. This study measured six reproduction traits in a Sichuan white goose population (209 individuals), including fertility, qualified egg rate, plasma concentrations of progesterone (P), follicle-stimulating hormone (FSH), prolactin (PRL) and oestrogen (E2). 2. Whole-genome resequencing data from the same goose population (209 individuals) were used in a genome-wide association study (GWAS) utilising a mixed linear model to investigate the genes and genetic markers associated with reproduction traits. The frequency of the selected SNPs and haplotypes were determined using the Matrix-Assisted Laser Desorption Ionization Time-Of-Flight Mass Spectrometry (MALDI-TOF MS) method. 3. In total, 42 SNPs significantly associated with these traits were identified. A haplotype block was constructed based on five SNPs that were significantly associated with qualified egg rate, with individuals having the haplotype CCTTAAGGAA having the lowest qualified egg rate. 4. In conclusion, these results provided potential markers for marker-assisted selection to improve goose reproductive performance and a basis for elucidating the genetics of goose reproduction

Using comparative genomics to detect mutations regulating plumage variations in graylag (A. anser) and swan geese (A. cygnoides)

Although graylag geese (A. anser) showed similar plumages of white, grey, and white with grey patches compared to those in swan geese (A. cygnoides), it was believed the substantial molecular mechanism for plumage variations were different. To date, studies on genes responsible for diverse plumages among graylag geese were limited and causal mutations remain unknown. In this study, genomes from 57 individuals belonging to six breeds showing different plumages were sequenced at ∼10X depth. Firstly, the allele frequency differences (AFD) of variants on the scaffold394 (NW_013185915.1) between grey and white goose breeds (A. anser) was calculated and a genomic region between 768,290–779,889 bp was detected to carry candidate variants associated with plumages, including one SNP (g. 775,151G > T, ∼18.6 kb upstream of EDNRB2) found to be fixed in white geese. This region was overlapped with the one detected by the haplotype-based sweep analysis, in which significant signals defined a candidate region of 736,610–820,622 bp on the same scaffold. Results from the transcriptomic data showed that expression levels of EDNRB2 and many other melanogenesis-related genes were significantly decreased among white geese compared to that in grey geese, especially at late embryonic stages (>E15). Modifications at transcriptional levels might result in abnormal melanocyte developments and thus the white plumages when they grow up. In addition, a frameshift mutation (C > -) in exon4 of MLANA gene on scaffold176 (NW_013185876.1) was suggested as the causal mutation for sex-linked dilution phenotype in graylag geese although this requires more demonstration experiments. Together with observed white plumages caused by EDNRB2 mutations in coding regions among swan geese and chicken, our study provided new examples to study the parallel evolution.

​​Expression of Frizzled-4 Gene on Developing and Postnatal Anser anser and Anser cygnoides Feather Follicles

Background: Frizzled (FZD) family works with the ligand Wnt protein to mediate downstream signals in the Wnt signaling pathway, while playing a superior role in the body. Therefore, this study was carried out to detect the expression patterns of FZD4 at the gene and protein levels. Methods: 10 developing and postnatal geese dorsal skin of Anser anser (n=5) and Anser cygnoides (n=5). Quantitative real-time polymerase chain reaction (qPCR) and western blotting were used to detect relative expression levels of FZD4. Feather follicles membrane localization was examined using immunohistochemistry. Student’s t-test and one-way ANOVA were used for statistical analysis. Result: The results revealed that the FZD4 was expressed differently at mRNA and protein levels at six stages. Furthermore, the positive expression sites of FZD4 protein were gradually transferred from dermal papilla; pulp; follicle wall and feather sheath. These results suggest that FZD4 is expressed in the growth and development of feather follicles for Anser anser and Anser cygnoides.

In Ovo Injection of CHIR-99021 Promotes Feather Follicle Development via Modulating the Wnt Signaling Pathway and Transcriptome in Goose Embryos (Anser cygnoides).

Feather performs important physiological functions in birds, and it is also one of the economic productions in goose farming. Understanding and modulating feather follicle development during embryogenesis are essential for bird biology and the poultry industry. CHIR-99021 is a potent Wnt/β-catenin signaling pathway activator associated with feather follicle development. In this study, goose embryos (Anser cygnoides) received an in ovo injection of CHIR-9902, which was conducted at the beginning of feather follicle development (E9). The results showed that feather growth and feather follicle development were promoted. The Wnt signaling pathway was activated by the inhibition of GSK-3β. Transcriptomic analyses showed that the transcription changes were related to translation, metabolism, energy transport, and stress in dorsal tissue of embryos that received CHIR-99021, which might be to adapt and coordinate the promoting effects of CHIR-99021 on feather follicle development. This study suggests that in ovo injection of CHIR-99021 is a potential strategy to improve feather follicle development and feather-related traits for goose farming and provides profiling of the Wnt signaling pathway and transcriptome in dorsal tissue of goose embryos for further understanding of feather follicle development.

Wild Bird Densities and Landscape Variables Predict Spatial Patterns in HPAI Outbreak Risk across The Netherlands.

Highly pathogenic avian influenza viruses’ (HPAIVs) transmission from wild birds to poultry occurs globally, threatening animal and public health. To predict the HPAI outbreak risk in relation to wild bird densities and land cover variables, we performed a case-control study of 26 HPAI outbreaks (cases) on Dutch poultry farms, each matched with four comparable controls. We trained machine learning classifiers to predict outbreak risk with predictors analyzed at different spatial scales. Of the 20 best explaining predictors, 17 consisted of densities of water-associated bird species, 2 of birds of prey, and 1 represented the surrounding landscape, i.e., agricultural cover. The spatial distribution of mallard (Anas platyrhynchos) contributed most to risk prediction, followed by mute swan (Cygnus olor), common kestrel (Falco tinnunculus) and brant goose (Branta bernicla). The model successfully distinguished cases from controls, with an area under the receiver operating characteristic curve of 0.92, indicating accurate prediction of HPAI outbreak risk despite the limited numbers of cases. Different classification algorithms led to similar predictions, demonstrating robustness of the risk maps. These analyses and risk maps facilitate insights into the role of wild bird species and support prioritization of areas for surveillance, biosecurity measures and establishments of new poultry farms to reduce HPAI outbreak risks.

Evidence for the Existence of Two Prolactin Isoforms in the Developing Pituitary Gland of the Goose (Anser cygnoides)

Compared to Galliformes such as chicken and turkey, very little is known about the existence and expression of isoforms of prolactin (PRL) in the pituitary glands of Anseriformes. In this study, by generating a rabbit-anti-goose (Anser cygnoides) PRL polyclonal antibody, we analysed the expression patterns of goose PRL isoforms in the embryonic and post-hatch development of the pituitary gland. Our results showed that two immunoreactive bands with molecular weights of about 23 and 26 kDa were detected using the Western blot technique, corresponding to the non-glycosylated (NG-) and the glycosylated (G-) isoform of PRL, respectively. The protein levels of the total PRL in a goose increased gradually from the embryonic day (ED) 22 to the post-hatch day (PD) 28, with a non-significant decrease on PD6. Furthermore, the percentage of G-PRL in the pituitary gland of the goose fluctuated from about 30.3% to 54.7% throughout the embryonic and post-hatch development. At the mRNA level, the expression of PRL increased steadily during the development and reached the highest levels on PD12, but later showed a non-significant decrease on PD28. The inconsistent expression patterns between the PRL mRNA and protein during the stages from PD6 to PD28 indicated that the PRL gene expression involves both transcriptional and post-translational regulation. Taken together, our data unequivocally demonstrated the existence of NG- and G-PRL in the pituitary gland of a goose and that the expression of the total PRL as well as the percentage of G-PRL significantly changed during embryonic and post-hatch development, indicating that the versatile biological functions of PRL during the ontogenesis of a goose could be closely related to changes in both its total expression and the degree of glycosylation in the pituitary gland.

Integrated analysis of microRNA and mRNA interactions in ovary of counter-season breeding and egg-ceased geese (Anser cygnoides)

Egg-ceasing is a phenomenon that occurs in most avian species and significantly reduces productivity. Although several factors are reported to regulate the reproduction progress, the underlying molecular mechanism of egg-ceasing remains obscure. Herein, we identified and explored the differentially expressed miRNAs and mRNAs involved in ovarian atrophy via high throughput sequencing. We identified a total of 901 mRNAs and 50 miRNAs that were differentially expressed in egg-laying and atrophic ovaries. Among them, numerous differentially expressed gene (DEG) transcripts and target genes for miRNAs were significantly enriched in Gene Ontology terms such as reproductive processes, cell proliferation, and apoptosis pathways. In addition, an interaction network was constructed by considering target relationships and correlation of the expression levels between ovary development-related genes, miRNAs and pathways. We discovered mRNA and miRNAs transcripts that are candidate regulators of ovary development in egg-ceased geese. Our findings expanded our understanding of the functional of miRNAs in ovarian atrophy and demonstrated that RNA-Seq is a powerful tool for examining the molecular mechanism in regulating egg-ceasing.

Potential Habitats and Their Conservation Status for Swan Geese (Anser cygnoides) along the East Asian Flyway

Habitats provide essential space for migratory birds to survive and reproduce. Identifying potential habitats in annual cycle stages and their influencing factors is indispensable for conservation along the flyway. In this study, we obtained satellite tracking of eight swan geese (Anser cygnoides) wintering at Poyang Lake (28°57′4.2″, 116°21′53.36″) from 2019 to 2020. Using the Maximum Entropy species distribution model, we investigated the potential habitats distribution of the swan geese during their migration cycle. We analyzed the relative contribution of various environmental factors to habitat suitability and conservation status for each potential habitat along the flyway. Our results show that the primary wintering grounds of swan geese are located in the middle and lower reaches of the Yangtze River. Stopover sites were widely distributed, mainly in the Bohai Rim, the middle reaches of the Yellow River, and the Northeast Plain, and extended westward to Inner Mongolia and Mongolia. Breeding grounds are mainly in Inner Mongolia and eastern Mongolia, while some are scattered in Mongolia’s central and western. The contribution rates of major environmental factors are different in breeding grounds, stopover sites, and wintering grounds. Breeding grounds were influenced by slope, elevation, and temperature. Slope, human footprint index, and temperature were the main factors that affected stopover sites. Wintering grounds were determined by land use, elevation, and precipitation. The conservation status of habitats is 9.6% for breeding grounds, 9.2% for wintering grounds, and 5.3% for stopover sites. Our findings thus provide a critically international assessment of potential habitats protection for geese species on the East Asian Flyway.

Molecular characterization and expression profiling of FOXL2 gene in goose (Anser cygnoides)

Forkhead box L2 (FOXL2) is a forkhead transcription factor essential for proper reproductive function in females and plays a crucial role in ovarian development in many species of vertebrates. However, little research on goose FOXL2 gene has been conducted. In this study, the cDNA and genomic DNA sequences of goose FOXL2 gene were cloned and characterized. The goose FOXL2 is a single exon gene and contains one open reading frame of 918bp encoding a protein of 305 amino acids. Bioinformatics analysis displays that the deduced FOXL2 amino acid sequence contains the highly conserved forkhead box domain, which shares greatest similarity to avian species, especially to that of ducks and chicken. RT-qPCR analysis indicates that the FOXL2 mRNA is widely expressed in all examined tissues of fertilized female eggs (28 days), and differentially expressed in female adult (70 days) and laying Zhedong White geese (270 days). Meanwhile, FOXL2 is highly expressed in the hypothalamic-pituitary-ovarian axis, especially in the ovary tissues of the adult and laying geese. Furthermore, one microsatellite (TGTC1415-1418----) and five single nucleotide polymorphisms (A1290G, G1495A, T1554C, T1692A, C1695G and T1697G) were identified in the 3'-untranslated regions. All the information derived from this study could be valuable and facilitate further researches on the function of FOXL2 gene in geese.

Philophthalmus gralli in domestic waterfowl: An environmental study in an urban area from Brazil.

Philophthalmosis is a zoonotic ocular disease that affects mainly domestic and wild avian species in different parts of the world. However, aspects related to its epizoology in domestic animals are not completely known. In the present study, 47 Muscovy duck (Cairina moschata), 8 mallards (Anas platyrhynchos platyrhynchos) and 6 African geese (Anser cygnoides), free-living in an urban lake in Belo Horizonte, Minas Gerais, Brazil, were evaluated for eye fluke infection. The animals were manually contained, and the conjunctival sac and nictitating membrane were evaluated by direct ophthalmic examination (DOE), in which the fluke burden was estimated by a semiquantitative scale. Moreover, the conjunctival sac lavage (CSL) technique was applied for the search of parasite eggs. When possible, the detected trematodes were carefully removed for fixed for taxonomic identification. In order to characterize the parasite-host-environmental system, malacological collections were performed at the locality, and the collected intermediate host mollusks (Melanoides tuberculata) were evaluated for infection with larval philophthalmids. In addition, wild vertebrates found dead in the locality, including one common gallinule (Gallinula galeata) and two capybaras (Hydrochoerus hydrochaeris), were necropsied for the search of eye flukes. Samples from the developmental stages obtained from the hosts were subjected to morphological and molecular studies (amplification and sequencing of a partial region of the Nad-1 gene). In the DOE, the presence of eye flukes was verified in 67% (4/6), 31% (15/47) and 25% (2/8) in geese, Muscovy ducks and mallards, respectively. In most cases, the birds showed mild parasitism (1-5 trematodes), with no apparent eye damage, characterizing a subclinical infection. In only one goose, which had a high fluke burden (20 trematodes), it was possible to obtain eggs by CSL. Regarding the malacological survey, 73/4545 (1.6%) specimens of M. tuberculata evaluated were found infected with megalurous cercariae, compatible with representatives of the family Philophthalmidae. Additionally, 147 flukes were recovered from a specimen of G. galeata found dead at the lake. The morphological and molecular study of parasites obtained from different hosts evaluated in this study enabled the identification of Philophthalmus gralli, a species native from Asia and introduced in the Americas. Factors such as the wide distribution of the intermediate host and the participation of domestic and wild reservoirs in the parasite transmission chain may favor the occurrence of parasite spillover from wild to domestic birds. Furthermore, the occurrence of the life cycle of P. gralli in an urban waterbody serves as an alert to the possibility of human cases of this zoonotic eye parasite.

Isolation and Identification of a Highly Pathogenic Avian Influenza H5N6 Virus from Migratory Waterfowl in Western Mongolia.

In April 2020, two Whooper Swans (Cygnus cygnus) and one Swan Goose (Anser cygnoides) were found dead at three different locations in western Mongolia. Virus isolation from organs taken from the carcasses and full genome sequencing revealed that all three birds were positive for highly pathogenic H5N6 avian influenza virus (HPAIV) belonging to subclade 2.3.4.4h. Confirming similar reports from central Mongolia and western China, these findings have important implications for the monitoring, control, and management of HPAIVs in wild bird and commercial poultry populations in Mongolia.

Surto de botulismo tipo C em aves aquáticas de vida livre em Goiás

ABSTRACT: Botulism is generally a fatal disease caused by ingestion of neurotoxins produced by Clostridium botulinum. The present study describes the epidemiological, clinical, and laboratory aspects of a type C botulism outbreak in free-living aquatic birds residing in an urban park in Quirinópolis, Goiás, Brazil. Among a population of approximately 80 waterfowl, a total of 30 birds, including ducks (Cairina moschata), teals (Anas platyrhynchos), and geese (Anser cygnoides), died within 10 days. Of these, six birds showed signs of flaccid paralysis of the pelvic limbs, eyelids, neck, and wings. To confirm the suspicion of botulism, four lake water samples, two samples of the feed consumed by the birds, and samples of serum, intestinal content, stomach content, and liver tissue from two teals that died after presenting clinical signs were analyzed. Using bioassay and neutralization with homologous antitoxin in mice, it was possible to detect the presence of botulinum toxin type C in a water sample and in the intestinal content of one of the necropsied teals. Additionally, the presence of C. botulinum type C was identified in the lake water using polymerase chain reaction. Based on the clinical signs and laboratory results, a diagnosis of botulism caused by botulinum toxin type C was confirmed with probable transmission by lake water.

Effect of Different Extenders on Sperm Motility and Vitality in Goose Semen Cryopreservation

This study aimed to investigate the usability of different diluents containing 6% Dimethylformamide (DMF) for cryo-preservation of the semen of geese (Anser cygnoides). The diluents of Glucose (G), Tris-Glucose (T), Lactated Ringer’s-Glucose (LG), and Lactated Ringer’s (L), all of which contained 6% DMF, were used as cryoprotectants. The researchers collected semen samples from four geese, twice a week over a four-week period, by means of abdominal massage; they then calculated how much sperm each goose ejaculated. Next, the semen samples were pooled and their spermatological parameters were determined. Their volume (4x (mL)), concentration (×108/mL), pH, motility (%), and vitality (%) rates were 0.31±0.01, 3.49±0.32, 7.13±1.06, 67.75±1.28, and 70.00±2.03, respectively. Then, these pooled semen samples were equally divided into four groups. Once they were frozen and thawed, the researchers discovered that the diluent L had the highest motility rate: 40.12% ± 1.35. The motility rates of the other diluents were as follows: LG (28.25%± 1.48), G (21.50% ± 1.41), and T (5.12% ± 0.83). Likewise, the vitality rates (%) of the diluents were as follows: L (41.93% ±1.87), LG (31.50%±1.88), G (29.43% ±1.45), and T (10.56%±1.34), respectively. Freezing and thawing appeared to lower each diluent’s vitality and motility rates. However, for the Lactated Ringer’s (L), this decrease was predictable. Therefore, Lactated Ringer’s diluent containing 6% DMF can be used in cryo-preservation of goose semen.

Comparative Analysis on the Duodenal Microbiota Community in Geese Fed with the All-grass or Basal Diet

Geese (Anser cygnoides) possess stronger ability of roughage digestion and utilization than other poultries, hence, it has become the focus of attention of scientists. Duodenal, jejunum and ileum were mainly participated in food digestion and nutrient absorption, while the cecum was responsible for biological fermentation. Effects on the geese’s cecal microbiota community by feeding with the all-grass diet have been investigated, however, whether it had an influence on the geese’s duodenal microbiota community remains unexplored. To address this problem, geese feeding with the basal diet for 28 days (G1), the basal diet for 28 days and the all-grass diet for the following 14 days (G2), the basal diet for 42 days (G3) were selected, respectively. The duodenal segments of geese were collected and the hypervariable V3-V4 region of the bacterial 16S rRNA gene was sequencing. A total of 4 main phyla and 16 main genera were identified. Moreover, we also successfully identified that two taxa including the Helcococcus and Clostridium could be used as distinguishing biomarkers specific to G2. The functional profiles of the duodenum microbiota were mainly involved in the membrane transport (e.g. ABC transporters), amino acid metabolism, energy metabolism, metabolism of cofactors and vitamins, and cellular processes and signaling pathways in geese feeding with the all-grass diet. In conclusion, the all-grass diet could impact the composition of duodenal microbiota. However, to resolve the underlying mechanism of the fiber digesting and utilization in geese’s gut microbiota, the whole intestinal system needs to be assessed by further studies.

Insulin-like growth factor 2 (IGF2) gene: molecular characterization, expression analysis and association of polymorphisms with egg production traits in goose (Anser cygnoides)

Insulin-like growth factor 2 (IGF2) belongs to the member of the insulin-like growth factors family, which plays key roles in animal growth, differentiation and proliferation, as well as reproduction and the regulation of ovarian follicle development. However, little is known about the goose IGF2 gene. In this study, a 1879 bp fragment that covered the complete coding region (CDS) of goose IGF2 cDNA was identified for the first time. The cDNA consists of an open reading frame of 574 nucleotides with the capacity to encode a prepro-IGF-II protein of 187 amino acids, which comprises a signal peptide (24 residues), IGF-II peptide (67 residues), and C-terminal peptide (96 residues), and is closely related to that of chicken. qPCR indicates that the goose IGF2 mRNA is differentially expressed in all examined tissues of fertilized eggs (28 days) and laying Zhedong White geese (270 days). Two novel single nucleotide polymorphisms (SNPs) were detected in exon 1 (G63A, Chr2: G26541617A) and intron 1 (G38A, Chr2: G26541479A) regions, and the synonymous mutation G63A showed a significant association with egg numbers (E180d) of Sanhua goose population (p < 0.05). All the information derived from this study could be valuable and facilitate further studies on the functions of goose IGF2 gene.

Research Note: Comparison on laying behavior and clutch traits among Zhedong white geese (Anser cygnoides), Sichuan white geese (Anser cygnoides), and Hungarian geese (Anser anser)

Egg laying is an important reproductive behavior of female poultry. Here, we investigated the laying behavior and clutch traits of different goose breeds, specifically, Zhedong white geese (Anser cygnoides), Sichuan white geese (Anser cygnoides) and Hungarian geese (Anser anser). A total of 108 geese in their first laying year were selected. Their laying rhythm was monitored daily by video cameras during the egg-laying period. The results showed that the prenatal behavior included nest hunting, nest site selection and nesting, as well as laying behavior included prenatal crouching, anal contraction until oviposition and postnatal resting. There were some differences in laying times among the 3 breeds. Approximately 70% of the eggs were laid between 03:00 and 12:00 in Zhedong white geese and Sichuan white geese, while the Hungarian geese laid throughout the day. Also, the clutch length and the oviposition interval differed among these 3 breeds. Their average clutch lengths were approximately 14.07, 12.14 and 19.15 days in Zhedong white geese, Sichuan white geese, and Hungarian geese, respectively. While their oviposition intervals showed 2 peaks (39 and 47 h), 3 peaks (41, 50 and 53 h), and 1 peak (46 h). Moreover, there were significant correlation between egg yield and clutch length in Zhedong white geese (r = 0.951), Sichuan white geese (r = 0.987) and Hungarian geese (r = 0.991), respectively. Taken together, the difference in laying behavior among the breeds was mainly reflected in laying time and oviposition intervals, Zhedong white geese and Sichuan white geese have egg laying time preference and short oviposition intervals, which was helpful not only to understand egg-laying process, but also to manage egg-laying geese scientifically and improve egg production.

Seasonal and regional differences in migration patterns and conservation status of Swan Geese (Anser cygnoides) in the East Asian Flyway

BackgroundThe Swan Goose (Anser cygnoides) breeds across Mongolia and adjacent China and Russia and winters exclusively in China. It is globally threatened, showing long-term major range contractions and declining abundance, linked to habitat loss and degradation. We remain ignorant about the biogeographical subpopulation structure of the species and potential differences in their migration timing, stopovers and schedules, information that could be vital to effective conservation of different elements of the species population, which we address here with results from a telemetry study.MethodsIn 2017–2018, we attached GPS/GSM telemetry devices to 238 Swan Geese on moulting sites in three discrete parts of their summering area (Dauria International Protected Area, Central Mongolia and Western Mongolia), generating 104 complete spring and autumn migration episodes to compare migration speed and nature between birds of different summer provenances.ResultsBirds from all three breeding areas used almost completely separate migration routes to winter sympatrically in the Yangtze River floodplain. Although many features of the spring and autumn migrations of the three groups were similar, despite the significantly longer migration routes taken by Western Mongolian tagged birds, birds from Dauria Region arrived significantly later in winter due to prolonged staging in coastal areas and took longer to reach their breeding areas in spring. Among birds of all breeding provenances, spring migration was approximately twice as fast as autumn migration. Areas used by staging Swan Geese (mainly wetlands) in autumn and spring almost never fell within national level protected areas, suggesting major site safeguard is necessary to protect these critical areas.ConclusionsThis study showed the discreteness of migration routes taken by birds of different summer provenances and differences in their migratory patterns, highlighting key staging areas (Yalu River Estuary in China/North Korea for Dauria Region breeding birds, Daihai Lake for Central Mongolian and Ordos Basin for Western Mongolian birds). Based on this new knowledge of the biogeographical subpopulation structure of the Swan Goose, we need to combine data on subpopulation size, their distribution throughout the annual life cycle and conservation status, to develop more effective conservation strategies and measures to reverse population decline throughout the range.

Winter coexistence in herbivorous waterbirds: Niche differentiation in a floodplain, Poyang Lake, China.

The classical niche theory supports the idea that stable coexistence requires ecological differences between closely related species. However, information on waterbirds coexistence in the entirely landlocked freshwater system of Poyang Lake is not well understood, especially when the available biomass of their food in the area decreases. In this study, we tested the ecological segregation mechanisms in the 2015/2016 and 2016/2017 wintering periods among eight herbivorous waterbirds (including the Siberian crane Grus leucogeranus, hooded crane Grus monacha, white‐naped crane Grus vipio, common crane Grus grus, greater white‐fronted goose Anser albifrons, bean goose Anser fabalis, swan goose Anser cygnoides, and tundra swan Cygnus columbianus) at Poyang Lake. Using field observations and species niche and foraging habitat selection models, we investigated the abundance, distribution, and food sources of these eight waterbird species to quantify and compare their habitat use and ecological niches. Our results showed that niche segregation among the waterbirds, with respect to food types, time, and spatial location, allow them to coexist and use similar resources. The water level gradually receded in the sub‐lakes of the Poyang Lake, which could provide food sources and various habitats for wintering herbivorous waterbirds to coexist. We demonstrated that the differences in habitat use could mitigate interspecific competition, which may explain the mechanism whereby waterbirds of Poyang Lake coexist during the wintering period, despite considerable overlap in the dietary niches of herbivorous waterbirds.