Blue-crowned Laughingthrush Research Articles

Genetic diversity of the critically endangered Blue‐crowned laughingthrush (Garrulax courtoisi)

AbstractTo evaluate the genetic quality and provide available management strategies for Blue‐crowned laughingthrush (BCLT), fifteen polymorphic microsatellite loci were developed and applied. The genetic diversity of wild individuals was indicated to be higher than the two captive populations. The average number of alleles (5.50 ± 0.317), the number of effective alleles (3.417 ± 0.222), observed heterozygosity (0.828 ± 0.04), and genetic differentiation index (0.028 ± 0.007) of 64 wild individuals showed high genetic diversity despite drastic bottleneck and low genetic differentiation. The number of effective migrants (22.737 ± 8.318) indicated the intriguing wintering grounds may be surrounded by the breeding sites where the syncheimadia occurred in Wuyuan. Efficient conservation, winter flocking, and cooperative breeding may facilitate gene exchange and inclusive fitness. We recommend that monitoring concentrated distribution areas for BCLT should be strengthened, and geographical barriers, interference types, and the inner mechanism of distribution patterns should be further explored.

Nesting Habitat Selection and Suitable Breeding Habitat of Blue-Crowned Laughingthrush: Implication on Its Habitat Conservation

Understanding the impact of human disturbance on the breeding habitat selection of endangered species is critical to improving their conservation. Blue-crowned Laughingthrush Pterorhinus courtoisi (Ménégaux, 1923) syn. Garrulax courtoisi (Passeriformes: Leiotrichidae) is an endangered species in China. To explore the nesting habitat selection of the Blue-crowned Laughingthrush and its response to human disturbance during the breeding period, we conducted a field survey at its nesting sites in Wuyuan County and Dexing City, Jiangxi Province, from March to July 2021 and in June 2022. At the home range scale (200 m) the results of a principal component analysis (PCA) showed that this species had a clear preference for infrastructure construction, grassland, farmland and bare land. At the microhabitat scale (12.26 m), we compared the ecological parameters of a nest plot and control plot using a Kruskal–Wallis H test and found that there were significant differences in the vegetation coverage, crown breadth, shrub coverage, herb maximum height, herb average height and herb species number of the nesting area between the two groups. Ensemble species distribution models showed that the suitable habitat of the Blue-crowned Laughingthrush covered an area of 108.63 km2. Distance to waterways, deciduous broadleaved forests and roads were the main factors impacting the habitat distribution of the Blue-crowned Laughingthrush. Our study suggests that (1) it is highly important to improve the protection of breeding sites and suitable living areas close to the settlements and preserve a certain nesting habitat selection space for the Blue-crowned Laughingthrush during the breeding period; and (2) it is necessary to continue to monitor the potential suitable breeding habitat. This study provides a scientific basis for the protection of the Blue-crowned Laughingthrush by local forestry bureaus and conservation departments in the future.

A RETROSPECTIVE ANALYSIS OF MORBIDITY AND MORTALITY IN CAPTIVE BLUE-CROWNED LAUGHING THRUSHES (PTERORHINUS COURTOISI): 1998-2018.

The blue-crowned laughingthrush (BCLT) (Pterorhinus courtoisi) is a species of critically endangered passerine that is part of a Global Species Management Plan and experiences high mortality rates in some collections. Complete necropsy and medical records from 15 European institutions that housed BCLT between 1998 and 2018 were assessed to evaluate morbidity and mortality in the captive population. Medical records for 407 BCLT were received; a total of 191 morbidity events were recorded from 111 individual BCLT. The most common cause of morbidity was coccidial disease, including systemic isosporosis (30.4%, n = 58). Age was a significant factor contributing to mortality, with 53% of deaths occurring between 0 and 14 d old and 78% by 1 yr of age. The most common cause of death was trauma (22.8%, n = 31), followed by systemic isosporosis (22%, n = 30). Of the 343 deceased birds for which records were provided, 50.4% had a necropsy performed and 40.5% had histopathology carried out postmortem. Based on these findings, BCLT should be managed carefully to mitigate risk of trauma, and screening for isosporosis should be performed. Institutions should carry out standardized necropsies and histopathology on every BCLT that dies in their collection to elucidate the etiology of disease in this critically endangered species.

Genomic signatures and evolutionary history of the endangered blue-crowned laughingthrush and other Garrulax species

BackgroundThe blue-crowned laughingthrush (Garrulax courtoisi) is a critically endangered songbird endemic to Wuyuan, China, with population of ~323 individuals. It has attracted widespread attention, but the lack of a published genome has limited research and species protection.ResultsWe report two laughingthrush genome assemblies and reveal the taxonomic status of laughingthrush species among 25 common avian species according to the comparative genomic analysis. The blue-crowned laughingthrush, black-throated laughingthrush, masked laughingthrush, white-browed laughingthrush, and rusty laughingthrush showed a close genetic relationship, and they diverged from a common ancestor between ~2.81 and 12.31 million years ago estimated by the population structure and divergence analysis using 66 whole-genome sequencing birds from eight laughingthrush species and one out group (Cyanopica cyanus). Population inference revealed that the laughingthrush species experienced a rapid population decline during the last ice age and a serious bottleneck caused by a cold wave during the Chinese Song Dynasty (960–1279 AD). The blue-crowned laughingthrush is still in a bottleneck, which may be the result of a cold wave together with human exploitation. Interestingly, the existing blue-crowned laughingthrush exhibits extremely rich genetic diversity compared to other laughingthrushes. These genetic characteristics and demographic inference patterns suggest a genetic heritage of population abundance in the blue-crowned laughingthrush. The results also suggest that fewer deleterious mutations in the blue-crowned laughingthrush genomes have allowed them to thrive even with a small population size. We believe that cooperative breeding behavior and a long reproduction period may enable the blue-crowned laughingthrush to maintain genetic diversity and avoid inbreeding depression. We identified 43 short tandem repeats that can be used as markers to identify the sex of the blue-crowned laughingthrush and aid in its genetic conservation.ConclusionsThis study supplies the missing reference genome of laughingthrush, provides insight into the genetic variability, evolutionary potential, and molecular ecology of laughingthrush and provides a genomic resource for future research and conservation.

Investigation on the characteristics of gut microbiota in critically endangered blue-crowned laughingthrush (Garrulax courtoisi).

Blue-crowned laughingthrush (Garrulax courtoisi), passeriformes, is a critically endangered bird endemic to China. Gut microbiota is well known to play a pivotal role in host health and survival. Thus, the understanding of the microbial communities associated with Garrulax courtoisi could be beneficial to save this species from the brink of extinction. In this study, we used 16s rDNA amplicon sequencing to investigate the gut community composition and microbial diversity of the Garrulax courtoisi population reared in Nanchang Zoo. The results showed that there were 31 phyla that were dominated by Firmicutes, Proteobacteria, Bacteroidetes, and Cyanobacteria in the intestine of Garrulax courtoisi. Compared with previous studies on birds, the Cyanobacteria exhibited an excessive abundance, which may be largely related to the personal lifestyle of Garrulax courtoisi. At the genus level, a total of 552 genera were identified, among which, 21 key genera constituted the core microbiome, including some culturable bacterial genera such as Lactobacillus, Acinetobacter, and Deinococcus. In the meanwhile, we found that there were remarkable intraspecific differences both in terms of microbial community structures, representative biomarkers and predicted functions between the parental generation and their offspring of the population investigated in this study. Furthermore, we also summarized their different eating behaviors and predicted its association with gut microbiota. This study provided the needed pieces of information about these extremely rare birds, Garrulax courtoisi, whose community composition and microbial diversity are hardly known. Importantly, these findings could contribute to our knowledge of the gut health of Garrulax courtoisi and advance the comprehensive conservation of this endangered bird.

Multiple lines of evidence confirm that the critically endangered Blue-crowned Laughingthrush (Garrulax courtoisi) is an independent species

The taxonomy of the Blue-crowned Laughingthrush (Garrulax courtoisi) and its relationship with the Yellow-throated Laughingthrush (G. galbanus) and G. c. simaoensis, a range-restricted subspecies in China, has not been fully elucidated. So the taxonomic status and system evolution of the three taxa G.courtoisi, G. galbanus and G. c. simaoensis need to be reclarified. Two gene sequences myoglobin (MYO) and the mitochondrial cytochrome coxidase subunit I (COI) were combined to investigate the phylogenetic relationships among courtoisi, simaoensis and galbanus, genetic data, combining with morphological, ecological and acoustic data were used to comb out the classification status and divergence level of the three taxa. Significant genetic and morphological differentiations (body size and plumage coloration) were detected between courtoisi and galbanus. However, no notable and reliable differences between the courtoisi and simaoensis were detected. The courtoisi, simaoensis and galbanus are clearly isolated in geographical distribution as a result of differing altitudes, climate conditions and habitats. The courtoisi has characteristic preference for nest location compared with galbanus. In addition, the results of song analysis also indicated that there are differences in maximum frequency between courtoisi and galbanus. G. courtoisi was confirmed to be an independent species based on genetic, morphological, geographical, ecological and vocal characteristics, and the validity of simaoensis as a subspecies still need more evidence. This study further confirmed the high conservation value of Blue-crowned Laughingthrush. In addition, due to the genetic differences between Simao and Wuyuan populations, this should be fully considered in future protection strategies.

Home range size and habitat use of the blue-crowned laughingthrush during the breeding season.

The home range size and habitat use of the blue-crowned laughingthrush (Garrulax courtoisi, hereafter BCLT), a critically endangered, subtropical, cooperative-breeding bird species in southeast China, were studied during its breeding period using radio telemetry at different sites during 3 consecutive years (2016–18, from May to June of each year). A total of 17 birds (12 males, four females, and one of unknown sex) were tagged, and a total 1515 locations (mean ± se = 89.12 ± 11.42) were obtained over 54 days of tracking. The average 100% minimum convex polygon (MCP) home range size was 10.05 ± 1.17 ha, and the estimated KDE core area (fiexed kernel density estimator, KDE) size was 7.84 ± 1.18 ha. According to the Wilcoxon rank sum tests, both the 100% MCP and KDE core area size of males did not significantly differ from those of females. There were no significant differences in the 100% MCP or KDE core area sizes of the three breeding sites. The available habitats in the breeding sites included water areas, shrubs, grass plots, woodland, residential areas, vegetable field, farmland, and sandy beaches; among them, only woodland was significantly preferred by BCLTs. Woodland (average use ratio was 45.86 ± 1.74%) was strongly preferred by BCLTs for nesting, foraging and roosting. Shrubs/grass plots (24.72 ± 3.39%) and vegetable plots (11.80 ± 1.83%) were used relatively more often than the other habitats, except woodland, since shrubs were always used as perches, and vegetable plots were rich in food resources. Vertically, the canopy layer was used most often from April to June, but it was used most in May when the birds were hatching and brooding. This result indicates that BCLT is predominantly active in the upper strata during the breeding season. In addition, broadleaved trees within or adjacent to villages were important activity areas for the breeding birds; protection and management measures should be increased in these areas.

Clinical and Pathological Aspects of Systemic Isospora Infection in Blue-crowned Laughing Thrushes (Garrulax courtoisi) at Jersey Zoo.

Based on a review of species mortalities, systemic Isospora species was identified as the primary cause of death in 22% (19 of 87) of blue-crowned laughing thrushes (BCLTs; Garrulax courtoisi) at the Jersey Zoo between 1997 and 2016. Fifty-eight percent of the affected birds were between 1 and 2 years old, and in 89% of cases, death occurred between August and December. Abnormal clinical findings in BCLTs with Isospora species infections included hepatomegaly and pectoral muscle myositis in 79% of the cases. The results of diagnostic blood testing in 90% of infected BCLTs 30 days before death were consistent with a severe leukocytosis with greater than 20% of mononuclear cells infected by merozoites. The most common lesions identified during gross necropsy examination were splenomegaly (100%), hepatomegaly (95%), and multifocal, raised, white foci in pectoral (84%) and heart (79%) muscle. Lymphohistiocytic inflammation was identified in the liver, heart, spleen, lung, striated muscle, and kidney tissue of birds with positive results for Isospora species. Merozoites were often observed in spleen, liver, pectoral muscle, and hearts of infected BCLTs. Polymerase chain reaction diagnostic testing that targeted the cytochrome c oxidase subunit, followed by Sanger sequencing, was used to confirm Isospora species in all 14 birds tested. Of samples tested, the highest genetic correlation was with GenBank accession number KT203397 (Isospora species JRB-2016 mitochondrion).

Low genetic diversity in captive populations of the critically endangered Blue-crowned Laughingthrush (Garrulax courtoisi) revealed by a panel of novel microsatellites.

BackgroundCaptive populations permit research and conservation of endangered species in which these efforts are hardly implemented in wild populations. Thus, analysing genetic diversity and structure of captive populations offers unique opportunities. One example is the critically endangered Blue-crowned Laughingthrush, Garrulax courtoisi, which has only two known wild populations in Wuyuan, Jiangxi and Simao, Yunnan, China. We carried out the first conservation genetic study, in order to provide useful implications that allow for successful ex situ conservation and management of the Blue-crowned Laughingthrush.MethodsUsing the novel microsatellite markers developed by whole-genome sequencing, we genotyped two captive populations, from the Ocean Park Hong Kong, which are of unknown origin, and the Nanchang Zoo, which were introduced from the Wuyuan wild population since the year 2010–2011, respectively. The genetic diversity of captive Blue-crowned Laughingthrush populations was estimated based on genetic polymorphisms revealed by a new microsatellite data set and mitochondrial sequences. Then, we characterised the population structure using STRUCTURE, principal coordinates analysis, population assignment test using the microsatellite data, and haplotype analysis of mitochondrial data. Additionally, we quantified genetic relatedness based on the microsatellite data with ML-Relate.ResultsOur results showed equally low levels of genetic diversity of the two captive Blue-crowned Laughingthrush populations. The population structure analysis, population assignment test using the microsatellite data, and haplotype analysis of the mitochondrial data showed weak population structuring between these two populations. The average pairwise relatedness coefficient was not significant, and their genetic relatedness was quantified.DiscussionThis study offers a genetic tool and consequently reveals a low level of genetic diversity within populations of a critically endangered bird species. Furthermore, our results indicate that we cannot exclude the probability that the origin of the Hong Kong captive population was the wild population from Wuyuan. These results provide valuable knowledge that can help improve conservation management and planning for both captive and wild Blue-crowned Laughingthrush populations.

蓝冠噪鹛繁殖期生境选择特征分析

蓝冠噪鹛繁殖期生境选择特征分析

INVESTIGATION OF THE PRESENCE OFATOXOPLASMASPP. IN BLUE-CROWNED LAUGHINGTHRUSH (DRYONASTES COURTOISI) ADULTS AND NEONATES

Between 1996 and 2013, 71 blue-crowned laughingthrush (Dryonastes courtoisi) chicks, a small passerine bird endemic to China, were born at Mulhouse Zoo in northeast France. None of them survived past 1 yr, and 82% died between 0 and 6 days old of an unidentified cause and despite an attempt to establish an artificial breeding protocol. Atoxoplasma spp., causing a disease known as systemic isosporosis, is a coccidian parasite that can infect several species of birds. Mulhouse's adult birds were suspected to be infected with Atoxoplasma spp. and to transmit this parasite to their offspring. A treatment with toltrazuril (Baycox® 2.5%) was implemented in the four adult birds. Coprologic examinations were performed before, during, and after the treatment to quantify the parasite load in feces. Polymerase chain reaction (PCR) assays were used to test blood samples from the adult and liver, lung, gizzard, and kidney samples from 10 chicks to detect Atoxoplasma spp. Five of the 10 chicks had some tissue samples positive for Atoxoplasma spp. in at least one of the three repeats of the atoxoplasmosis PCR. An average of 181 Isospora spp. oocysts per gram of feces were found in the group of adults before treatment. This number was reduced to zero 1 wk after the beginning of the toltrazuril treatment. The PCR results suggest a transovarian transmission of Atoxoplasma spp., but further investigation is needed for confirmation. The treatment with toltrazuril appears to allow a significant reduction of the parasite excretion.

The impact of disturbance from photographers on the Blue-crowned Laughingthrush (Garrulax courtoisi)

The impact of disturbance from photographers on the Blue-crowned Laughingthrush (Garrulax courtoisi)

A New Species of Isospora Schneider, 1881 (Apicomplexa: Eimeriidae) from the Blue-crowned Laughingthrush Dryonastes courtoisi (Passeriformes: Timaliidae)

A new species of Isospora Schneider (Apicomplexa: Eimeriidae) is described from captive Blue-crowned Laughingthrush Dryonastes courtoisi (Menegaux, 1923) (Passeriformes: Timaliidae). Sporulated oocysts of Isospora courtoisii n. sp. are ellipsoidal 24.5 × 14.5 μm. Micropyle and oocyst residuum are absent. Sporocysts are broadly ellipsoidal, 15.9 × 8.5 μm, with Stieda and substieda bodies. Sporocyst residuum is scattered composed of hundreds of small granules. Sporozoites are elongate and slightly curved, each with two refractile bodies. The nuclei of the sporozoites were not well discernible. Considering the critically endangered status of Dryonastes courtoisi and assumed high host specificity of described coccidium, also I. courtoisi can be classified as critically endangered organism.