Egretta Eulophotes Research Articles

Community Validation of Threatened Species in Coastal Wetland Areas of Negros Occidental, Philippines

This research aims to identify threatened bird species in wetland areas and define temporal changes occurring among species based on local observations and experiences. Survey, ethnobiology workshops, key informant interviews and focus group discussions were approaches employed in the collection of primary data from the chosen participants residing in the coastal communities in Central Negros, Philippines. The threatened wetland bird species in these sites are generally perceived as “abundant” as indicated by their perceived common presence. The ten sites also shared two vulnerable species, Egretta eulophotes,locally known as as Tulabong by locals and Anas luzonica called Pato ilahas by the natives. The Numenius madagascariensis is considered endangered and eight near threatened bird species (IUCN Red list), Numenius arquata, Limnodromus semipalmatus, Charadrius peronii, Limosa limosa, Limosa lapponica, Tringa brevipes, Calidris ruficollis and Calidris ferruginea, were validated by locals in almost all of the study sites. However, some threatened species were observed to have disappeared and declined in these areas. An updated list of threatened species found in coastal wetland cities and municipalities in the central area of Negros Occidental was produced that shall serve as basis for crafting relevant programs to properly manage, conserve and develop these wetland areas.

Waterbirds in the Wetlands of Casiguran, Aurora, Philippines

The wetlands of Casiguran, Aurora, Philippines are primarily the source of livelihood for most of the coastal communities of the area. However, this also serves as a feeding ground for many of the migratory and resident waterbirds. There are waterbird species occurring in the area that need protection but only a few studies of these species exist. This study was conducted from February to March 2019 to census and identify the water birds present in the study site, determine the conservation status and index of abundance of identified waterbirds, and describe their habitat association. Based on the result, 18 waterbird species in five families were present in the area. Family Ardeidae had six representative species, Family Charadriidae had five representative species, Family Scolopacidae had five representative species while only one species represents the Family Anatidae and Family Rallidae. Two waterbird species observed (Anas luzonica and Egretta eulophotes) were listed by the International Union for Conservation of Nature (IUCN) as vulnerable and another species (Numerius madagascariensis) was listed as endangered. In terms of abundance, Intermediate Egret (Egretta intermedia) was revealed as the most abundant (94.68%) among waterbirds. Different waterbird species prefer specific habitats. Some usually frequent freshwater and saltwater habitats, including mangroves, open sea, and watercourses inside forests while some were observed in mudflats, and rice fields during the survey.

Autumn migration routes of fledgling Chinese Egrets (Egretta eulophotes) in Northeast China and their implications for conservation

The Chinese Egret (Egretta eulophotes) is a globally threatened bird species living on the coast and islands of Liaoning, northeastern China, mainly in summer. To further protect the breeding population of Chinese Egrets, it is important to understand the current protection status of their distribution sites at pre-migration period and migration routes. Thirty-three individuals were tagged with satellite transmitters at Fantuo Island in Changhai and Xingren Island in Zhuanghe, Liaoning Province, northeastern China, in July of 2016, 2017, and 2018, to identify important distribution sites during the pre-migration period, as well as detailed migration routes. The results showed that coastal mudflats in Liaoning and the west coast of North Korea were important feeding and roosting sites for fledgling Chinese Egrets from August to September. The home range sizes in August were significantly larger than in September. The eastern coast from Shandong to Guangdong, as well as Taiwan, China, and Manila Bay and Galileo Islands in the Philippines, were important stopover sites during fall migration. Specifically, we found that the egrets’ autumn migration could be divided into four routes, i.e., sea-crossing migration (SCM), coastal migration (CM), inland migration (IM), and mixed migration (MM). The migration distance, timing, speed, and straightness of the four routes also differed. The SCM routes were the straightest, and had the fastest migration speed and shortest travel time, while the IM routes had the lowest straightness and speed, and the longest duration. Manila Bay and Bohol Island in the Philippines, the west coast of Tanintharyi in Myanmar, and the Zengwun River Estuary in Taiwan, China, were wintering sites. Our findings on the key distribution sites along pre-migration and fall migration routes, including some stopover sites, have important implications for the conservation of and global action plan development for the vulnerable Chinese Egret.

Migration and wintering of vulnerable adult Chinese Egrets (Egretta eulophotes) revealed by GPS tracking

Knowledge of migratory bird requirements is critical to developing conservation plans for vulnerable migratory species. This study aimed to determine the migration routes, wintering areas, habitat uses, and mortalities of adult Chinese Egrets (Egretta eulophotata). Sixty adult Chinese Egrets (31 females and 29 males) on an uninhabited offshore breeding island in Dalian, China were tracked using GPS satellite transmitters. GPS locations recorded at 2 ​h intervals from June 2019 to August 2020 were used for analysis. A total of 44 and 17 tracked adults completed their autumn and spring migrations, respectively. Compared with autumn migration, tracked adults displayed more diverse routes, higher number of stopover sites, slower migration speed, and longer migration duration in the spring. Results indicated that migrant birds had different behavioral strategies during the two migratory seasons. The spring migration duration and stopover duration for females were significantly longer than those for males. A positive correlation existed between the spring arrival and spring departure dates, as well as between the spring arrival date and stopover duration. This finding indicated that the egrets that arrived early at the breeding grounds left the wintering areas early and had a shorter stopover duration. Adult birds preferred intertidal wetlands, woodlands, and aquaculture ponds during migration. During the wintering period, adults preferred offshore islands, intertidal wetlands, and aquaculture ponds. Adult Chinese Egrets showed a relatively low survival rate compared with most other common ardeid species. Dead specimens were found in aquaculture ponds, indicating human disturbance as the main cause of death of this vulnerable species. These results highlighted the importance of resolving conflicts between egrets and human-made aquaculture wetlands and protecting intertidal flats and offshore islands in natural wetlands through international cooperation. Our results contributed to the hitherto unknown annual spatiotemporal migration patterns of adult Chinese Egrets, thereby providing an important basis for the conservation of this vulnerable species.

Autumn migration routes and wintering areas of juvenile Chinese Egrets (Egretta eulophotes) revealed by GPS tracking

BackgroundThe vulnerable Chinese Egret (Egretta eulophotes) is a long-distance migratory waterbird whose migration and wintering information is poorly understood. This study aims to identify the autumn migration routes and wintering areas of juvenile Chinese Egrets and determine the migration movement traits of this species.MethodsThirty-nine juvenile Chinese Egrets from the Fantuozi Island, an uninhabited offshore island with a large breeding colony of Chinese Egrets in Dalian, China, were tracked using GPS/GSM transmitters. Some feathers from each tracked juvenile were collected for molecular identification of sex in the laboratory. The GPS locations, recorded at 2-h intervals from August 2018 to May 2020, were used for the analyses.ResultsOf the 39 tracked juveniles, 30 individuals began their migration between September and November, and 13 successfully completed their autumn migration between October and November. The juveniles migrated southward via three migration routes, coastal, oceanic and inland, mainly during the night. The migration duration, migration distance, flight speed, and stopover duration of the 13 juvenile egrets that completed migration averaged 5.08 ± 1.04 days, 3928.18 ± 414.27 km, 57.27 ± 5.73 km/h, and 23.08 ± 19.28 h, respectively. These juveniles wintered in the coastal wetlands of Southeast Asia including those in the Philippines, Vietnam, and Malaysia, and only one successfully began its spring migration in June 2020.ConclusionsThis study newly finds that the oceanic route taken by juvenile Chinese Egrets, suggesting that the juveniles are able to fly over the Pacific Ocean without a stopover. Moreover, our novel data indicate that coastal wetlands along the East Asian–Australasian Flyway are important areas for both autumn migration stopover and the wintering of these juveniles, suggesting that international cooperation is important to conserve the vulnerable Chinese Egret and the wetland habitats on which it depends.

Primer development of toll-like receptor genes in the vulnerable Chinese egret (Egretta eulophotes) and its applicability in Ardeidae

Toll-like receptor (TLR) genes have recently been used to assess the adaptive genetic diversity under natural selection. Here, we newly developed a set of primer pairs for amplifying TLR genes (TLR1LB, TLR2A, TLR3, TLR4, TLR5, TLR7 and TLR15) in the vulnerable Chinese egret (Egretta eulophotes). The PCR products, ranged between 407 and 988 bp (an average of 762 bp), were successfully amplified by using this primer set. Sequence analyses of all these TLR genes indicated that there were 22–75 variable sites and 20–77 single nucleotide polymorphisms. This primer set was also confirmed useful for nine other ardeid species, including four members in ardeinae and five in botaurinae. The versatility of this primer set will provide a useful groundwork for the further studies on the TLR conservation genetics of this vulnerable egret and other ardeid birds.

Colonial Nesting Birds of Peter the Great Bay, Sea of Japan (Pelecaniformes, Ciconiiformes)

This study reports recent data on the distribution and breeding abundance of seven species of colonial birds on the coast of Peter the Great Bay, Sea of Japan. Over the past 30 years, three species of cormorants (great, Japanese, and pelagic cormorants), as well as the black-faced spoonbill, have significantly increased their numbers. The number of breeding pairs of gray heron and Chinese egret decreased, while the numbers of the little egret did not change.

Genetic diversity of toll-like receptor genes in the vulnerable Chinese egret (Egretta eulophotes).

Toll-like receptor (TLR) genes have recently been employed to assess genetic diversity, as they can be used to infer both demographic history and adaptation to environments with different pathogen pressure. Here, we sampled 120 individuals of the Chinese egret (Egretta eulophotes), a globally vulnerable species, from four breeding populations across China. We assessed the levels of genetic diversity, selection pressure, and population differentiation at seven TLR loci (TLR1LB, TLR2A, TLR3, TLR4, TLR5, TLR7, and TLR15). Using a variety of metrics (SNPs, heterozygosity, nucleotides, haplotypes), our analyses showed that genetic diversity was lower at 4 of the 7 TLR loci in the vulnerable Chinese egret compared to the more common little egret (Egretta garzetta). The selection test indicated TLRs, except for TLR5, were under purifying selection in TLR evolution, suggesting that low TLR genetic diversity in the Chinese egret may be caused by purifying selection. Moreover, analysis of molecular variance indicated low but significant population differentiation among four populations at all of the TLR loci in this egret. However, some comparisons based on fixation index analyses did not show significant population differentiation, and Bayesian clustering showed admixture. Our finding suggested that these four populations of the Chinese egret in China may be considered a single unit for conservation planning. These results, the new report of TLR genetic diversity in a long-distance migratory vulnerable Ardeid species, will provide fundamental TLR information for further studies on the conservation genetics of the Chinese egret and other Ardeids.

Organophosphate flame retardants in heron eggs from upper Yangtze River basin, southwest China

The egg samples of four heron species, including black-crowned night heron (Nycticorax nycticorax), little egret (Egretta garzetta), Chinese pond heron (Ardeola bacchus) and cattle egret (Bubulcus ibis), were collected from the upper Yangtze River (Changjiang) Basin, Southwest China in early summer of 2017. Nine out of ten target organophosphate flame retardants (PFRs) were detected in these heron egg samples. The sum of concentrations of the PFRs quantified (∑PFRs) ranged from 63 to 590 pmol g−1 ww (18–185 ng g−1 ww) with a median value of 139 pmol g−1 ww (48 ng g−1 ww) among all samples. The median ∑PFRs in eggs of night herons (160 pmol g−1 ww) was higher than Chinese pond herons (median 121 pmol g−1 ww) and little egrets (median 109 pmol g−1 ww). In heron eggs, ∑PFRs were mainly contributed by tri-n-butyl phosphate (TNBP), tris (isobutyl) phosphate (TIBP), tris (1-chloro-2-propyl) phosphate (TCIPP) and tri-2-methylphenyl phosphate (TMPP). Alkyl-PFRs accounted for approximately 28%–85% (median 57%) of the nine PFRs quantified while the rest is contributed by aryl-PFRs and chlorinated PFRs. Lower levels of PFRs in little egret eggs were found upstream than downstream of the Yangtze. In addition, the daily intakes of PFRs through ingestion of heron eggs were estimated at lower levels.

Mitochondrial CO1 genetic structure among breeding sites of Chinese egret (Egretta eulophotes) in South Korea

Chinese egret (Egretta eulophotes) is classified as an endangered species (VU, vulnerable) and is limited to Far East. This species breeds especially offshore in China, Russia, and the Korean peninsula. We analyzed partial mitochondrial cytochrome c oxidase 1 of the bird from five major breeding sites in South Korea. The results indicate that there were only 10 mitochondrial cytochrome c oxidase 1 haplotypes and that their genetic diversity is very low. In addition, the distribution pattern of the haplotypes is patchy, indicating that at least a population may be distinct in its maternal origin and migration route. The results may be used as a baseline of establishing the conservation program and international cooperation for this species.

Diversity and selection of MHC class I genes in the vulnerable Chinese egret (Egretta eulophotes).

The genes of major histocompatibility complex (MHC) are important to vertebrate immune system. In this study, two new MHC class I genes, designated as Egeu-UAA and Egeu-UBA, were discovered in the vulnerable Chinese egret (Egretta eulophotes). Using a full length DNA and cDNA produced by PCR and RACE methods, these two MHC class I loci were characterized in the genome of the Chinese egret and were also found to be expressed in liver and blood. Both new genes showed the expected eight exons and were similar to two copies of the minimal essential MHC complex of chicken. In genetic diversity, 14 alleles (8 for UAA and 6 for UBA) in the MHC class I gene exon 3 were found in 60 individuals using locus-specific primers and showed little polymorphism. Only three potential amino acid residues were detected under positive selection in potential peptide-binding regions (PBRs) by Bayesian analysis. These new results provide the fundamental basis for further studies to elucidate the molecular mechanisms and significance of MHC molecular adaptation in vulnerable Chinese egret and other ardeids, finding that have not been previously reported.

Type specimens and type localities of birds (Aves) collected during F. J. F. Meyen's circumnavigation in 1830-1832.

At least 32 bird species were described as new to science on the basis of material collected by Franz Meyen during his circumnavigation in 1830-1832. We identified the type specimens and determined the type localities of these species, which are currently housed in the Museum für Naturkunde, Berlin, Germany. Ardea longicollis Meyen, 1834, is identified as a senior synonym of Egretta eulophotes (Swinhoe, 1860), but is set aside as a nomen oblitum. The name of a Neotropical dove is corrected from Metriopelia ceciliae zimmeri (Peters, 1937) to Metriopelia ceciliae gymnops (Chubb, 1917). A lectotype is designated for Nectarinia philippensis Meyen, 1834a.

Population genetic diversity and geographical differentiation of MHC class II DAB genes in the vulnerable Chinese egret (Egretta eulophotes)

Major histocompatibility complex (MHC) genes are excellent markers for the study of adaptive genetic variation occurring over different geographical scales. The Chinese egret (Egretta eulophotes) is a vulnerable ardeid species with an estimated global population of 2600–3400 individuals. In this study, we sampled 172 individuals of this egret (approximately 6 % of the global population) from five natural populations that span the entire distribution range of this species in China. We examined their population genetic diversity and geographical differentiation at three MHC class II DAB genes by identifying eight exon 2 alleles at Egeu-DAB1, eight at Egeu-DAB2 and four at Egeu-DAB3. Allelic distributions at each of these three Egeu-DAB loci varied substantially within the five populations, while levels of genetic diversity varied slightly among the populations. Analysis of molecular variance showed low but significant genetic differentiation among five populations at all three Egeu-DAB loci (haplotype-based ϕST: 0.029, 0.020 and 0.042; and distance-based ϕST: 0.036, 0.027 and 0.043, respectively; all P < 0.01). The Mantel test suggested that this significant population genetic differentiation was likely due to an isolation-by-distance pattern of MHC evolution. However, the phylogenetic analyses and the Bayesian clustering analysis based on the three Egeu-DAB loci indicated that there was little geographical structuring of the genetic differentiation among five populations. These results provide fundamental population information for the conservation genetics of the vulnerable Chinese egret.

Major histocompatibility complex class II DAB alleles associated with intestinal parasite load in the vulnerable Chinese egret (Egretta eulophotes).

The maintenance of major histocompatibility complex (MHC) polymorphism has been hypothesized to result from many mechanisms such as rare‐allele advantage, heterozygote advantage, and allele counting. In the study reported herein, 224 vulnerable Chinese egrets (Egretta eulophotes) were used to examine these hypotheses as empirical results derived from bird studies are rare. Parasite survey showed that 147 (65.63%) individuals were infected with 1–3 helminths, and 82.31% of these infected individuals carried Ascaridia sp. Using asymmetric polymerase chain reaction technique, 10 DAB1, twelve DAB2, and three DAB3 exon 2 alleles were identified at each single locus. A significant association of the rare allele Egeu‐DAB2*05 (allele frequency: 0.022) with helminth resistance was found for all helminths, as well as for the most abundant morphotype Ascaridia sp. in the separate analyses. Egeu‐DAB2*05 occurred frequently in uninfected individuals, and individuals carrying Egeu‐DAB2*05 had significantly lower helminth morphotypes per individual (HMI) (the number of HMI) and the fecal egg count values. Further, the parasite infection measurements were consistently lower in individuals with an intermediate number of different alleles in the duplicated DAB loci. Significantly, heterozygosity within each DAB locus was not correlated with any parasite infection measurements. These results indicate that the diversity in MHC Egeu‐DAB gene is associated with intestinal parasite load and maintained by pathogen‐driven selection that probably operate through both the rare‐allele advantage and the allele counting strategy, and suggest that Egeu‐DAB2*05 might be a valuable indicator of better resistance to helminth diseases in the vulnerable Chinese egret.

Nest Characteristics of the Chinese Egret (Egretta europhotes) in South Korea1a

Nest Characteristics of the Chinese Egret (Egretta europhotes) in South Korea1a

Noninvasive and nondestructive sampling for avian microsatellite genotyping: a case study on the vulnerable Chinese Egret (Egretta eulophotes)

Noninvasive and nondestructive DNA sampling techniques are becoming more important in genetic studies because they can provide genetic material from wild animals with less or even without disturbance, which is particularly useful for the study of endangered species, i.e., birds. However, nondestructively and noninvasively sampled DNA may, in some cases, be inadequate in the amount and quality of the material collected, which can lead to low amplification success rates and high genotyping errors. In this study, noninvasive (eggshell swab, shed feather and feces), nondestructive (plucked feather and buccal swab) and invasive (blood) DNA samples were collected from the vulnerable Chinese Egret (Egretta eulophotes). DNA concentrations, PCR amplification success and microsatellite genotyping errors of different sample types were evaluated and compared to determine whether noninvasive and nondestructive samples performed as well as invasive samples in our experimental procedures. A total of 159 samples were collected in the field. Among the different sample types, the highest DNA concentrations (154.0–385.5 ng/μL) were obtained from blood. Those extracted from fecal samples were the lowest, ranging from 1.25 to 27.5 ng/μL. Almost all of the DNA samples, i.e., 95.59 %, were successfully amplified for mtDNA (n = 152) and 92.76 % of mtDNA samples were successfully genotyped for at least five of the nine microsatellite loci tested (n = 141). Blood samples and buccal swabs produced reliable genotypes with no genotyping errors, but in feces, allelic dropouts and false alleles occurred in all nine loci, with error rates ranging from 6.67 to 38.10 % for the dropouts and from 6.06 to 15.15 % for the false alleles. These results indicate that both nondestructive and noninvasive samplings are suitable for avian microsatellite genotyping, save for fecal DNA. However, we should remain cautious of the appearance of genotyping errors, especially when using noninvasive material.

Characterization of a non-classical MHC class II gene in the vulnerable Chinese egret (Egretta eulophotes).

Genes of the major histocompatibility complex (MHC) are valuable makers of adaptive genetic variation in evolutionary ecology research, yet the non-classical MHC genes remain largely unstudied in wild vertebrates. In this study, we have characterized the non-classical MHC class II gene, Egeu-DAB4, in the vulnerable Chinese egret (Ciconiiformes, Ardeidae, Egretta eulophotes). Gene expression analyses showed that Egeu-DAB4 gene had a restricted tissue expression pattern, being expressed in seven examined tissues including the liver, heart, kidney, esophagus, stomach, gallbladder, and intestine, but not in muscle. With respect to polymorphism, only one allele of exon 2 was obtained from Egeu-DAB4 using asymmetric PCR, indicating that Egeu-DAB4 is genetically monomorphic in exon 2. Comparative analyses showed that Egeu-DAB4 had an unusual sequence, with amino acid differences suggesting that its function may differ from those of classical MHC genes. Egeu-DAB4 gene was only found in 30.56-36.56% of examined Chinese egret individuals. Phylogenetic analysis showed a closer relationship between Egeu-DAB4 and the DAB2 genes in nine other ardeid species. These new findings provide a foundation for further studies to clarify the immunogenetics of non-classical MHC class II gene in the vulnerable Chinese egret and other ciconiiform birds.

A novel multiplex PCR assay for individual identification in the vulnerable Chinese Egret (Egretta eulophotes) using molted feathers

Noninvasive DNA may be used in individual identification for counting or tracking animals. Here a multiplex PCR assay, in which 16 highly polymorphic microsatellite markers were chosen and allocated into four multiplex PCR panels, was described for the individual identification of the Chinese Egret (Egretta eulophotes) using molted feathers. In this study, the combined exclusion probability for unrelated individuals (PID) and for individuals with sibling relationship (PID(sib)) were 7.02 × 10−19 and 2.9 × 10−7, respectively. Molted feathers (n = 59) of E. eulophotes amplified by more than 7 loci were unambiguously identified as 43 different individuals (32 females and 11 males). The results indicated that our newly developed assay could be used for noninvasive individual identification in the vulnerable Chinese Egret and other Ardeids.

Characterization, Polymorphism and Selection of Major Histocompatibility Complex (MHC) DAB Genes in Vulnerable Chinese Egret (Egretta eulophotes)

The major histocompatibility complex (MHC) is an excellent molecular marker for the studies of evolutionary ecology and conservation genetics because it is a family of highly polymorphic genes that play a key role in vertebrate immune response. In this study, the functional genes of MHC Class II B (DAB) were isolated for the first time in a vulnerable species, the Chinese egret ( Egretta eulophotes ). Using a full length DNA and cDNA produced by PCR and RACE methods, four potential MHC DAB loci were characterized in the genome of this egret and all four were expressed in liver and blood. At least four copies of the MHC gene complex were similar to two copies of the minimal essential MHC complex of chicken, but are less complex than the multiple copies expressed in passerine species. In MHC polymorphism, 19 alleles of exon 2 were isolated from 48 individuals using PCR. No stop codons or frameshift mutations were found in any of the coding regions. The signatures of positive selection detected in potential peptide-binding regions by Bayesian analysis, suggesting that all of these genes were functional. These data will provide the fundamental basis for further studies to elucidate the mechanisms and significance of MHC molecular adaptation in vulnerable Chinese egret and other ardeids.

Development and cross-species transferability of 23 microsatellite markers from the vulnerable Chinese Egret (Egretta eulophotes) using 454 sequencing

The Chinese Egret (Egretta eulophotes) is a vulnerable waterbird breeding on offshore islands. Here, 23 new microsatellite loci were isolated using 454 pyrosequencing, and were tested in 32 individuals from a single population in Fujian province of China. The number of alleles per locus ranged from 2 to 9. Observed heterozygosity and expected heterozygosity ranged from 0.094 to 0.844 and 0.091 to 0.840, respectively. All loci showed Hardy–Weinberg equilibrium with the exception of three loci (Ee10, Ee17 and Ee23), possibly because of null alleles. The new loci also were confirmed a high cross-amplification success rate in the other seven Ardeid species. These new microsatellite data will provide a major resource for future conservation genetics studies on this vulnerable egret and the other Ardeids.