Ecological drivers of nesting behavior in a subtropical city: An observational study on spotted doves.

Due to rapid homogenization in habitat types as a result of urbanization, some urban birds adapt their nesting strategies to changes in local habitat characteristics. Bird nesting decisions might have been mainly linked to resource constraints and ensuring reproductive success. In this study, we examined patterns of nesting behavior by spotted doves (Spilopelia chinensis) in a rapidly urbanizing area of Nanchang, China using ArcGIS 10.8, satellite tracking, camera traps, and field survey. To explore the mechanisms underlying nesting behavior in urban habitats, we assessed the correlations between nest reuse and reproductive success, and between nest reuse and nest predation. From December 2018 to December 2021, a total of 302 breeding nests were surveyed. The results revealed that the nest reuse rate was 38.08% (n = 115). Nests closer to trunk, with lower nest position and higher large-scale urbanization score tended to have higher reuse rate. In addition, nests with the higher the nest height and percent of canopy cover, and the lower small-scale urbanization score were more likely to reproduce successfully, and the reused nests also reproduce more successfully. The reproductive success associated with nest reuse was significantly higher than that associated with new nests (χ 2 = 8.461, p = .004). High degree of urbanization promoted nest reuse of spotted doves (large-scale urbanization score, z = 2.094, p = .036), which apparently enhanced their reproductive success (nest reuse, z = 2.737, p = .006). In conclusion, a nest structure with good permeability is the material basis for the nest reuse in spotted dove, while the relatively low risk of predation in urban habitat and the scarcity of nest site resources due to urbanization increase the tendency of birds to reuse old nests, which is associated with their reproductive success and evolutionary fitness.

Chronic lead exposure prolongs the immature stages of brown-legged grain mite, Aleuroglyphus ovatus, in a long-term population study.

An important aspect of environmental pollution, lead contamination is a widespread problem in several ecosystems. The present study aimed to evaluate the potential effects of low concentration lead stress on the development and reproduction of Aleuroglyphus ovatus. They were fed with artificial diet containing four different concentrations of lead (12.5, 25, 50, and 100 mg/kg). The results showed that there were both accelerating effect of lead (at low concentrations), as well as retarding effects (at high concentrations) on the development of the mite, and lead stress significantly prolonged the immature stages of A. ovatus and this inhibitory effect was greater with greater lead concentrations. The immature stages in the L group were shorter than those in the S group. In the S and L groups, the oviposition periods were significantly longer in the treatments with lower lead concentrations than in the control, while they were significantly shorter in those treatments of higher lead concentrations. Age-specific survival rate (lx) started to decline earlier in the S group, whereas there were no differences between the L group and CK. Age-specific fecundity rate (mx) peaked earlier in the S group than in CK, while mx peaked later in L1 and L2 than in CK. The rm value and net reproduction rate (R0) of treated A. ovatus decreased with increasing lead concentrations. Lower lead concentrations could promote population expansion while higher concentrations could inhibit population size. These results confirmed the developmental effect of lead stress on A. ovatus, highlighting that heavy metal contamination has negative effects on organisms in their natural environment.

Diet drives the gut microbiome composition and assembly processes in winter migratory birds in the Poyang Lake wetland, China.

The complex gut bacterial communities may facilitate the function, distribution, and diversity of birds. For migratory birds, long-distance traveling poses selection pressures on their gut microbiota, ultimately affecting the birds' health, fitness, ecology, and evolution. However, our understanding of mechanisms that underlie the assembly of the gut microbiome of migratory birds is limited. In this study, the gut microbiota of winter migratory birds in the Poyang Lake wetland was characterized using MiSeq sequencing of 16S rRNA genes. The sampled bird included herbivorous, carnivorous, and omnivorous birds from a total of 17 species of 8 families. Our results showed that the gut microbiota of migratory birds was dominated by four major bacterial phyla: Firmicutes (47.8%), Proteobacteria (18.2%), Fusobacteria (12.6%), and Bacteroidetes (9.1%). Dietary specialization outweighed the phylogeny of birds as an important factor governing the gut microbiome, mainly through regulating the deterministic processes of homogeneous selection and stochastic processes of homogeneous dispersal balance. Moreover, the omnivorous had more bacterial diversity than the herbivorous and carnivorous. Microbial networks for the gut microbiome of the herbivorous and carnivorous were less integrated, i.e., had lower average node degree and greater decreased network stability upon node attack removal than those of the omnivorous birds. Our findings advance the understanding of host-microbiota interactions and the evolution of migratory bird dietary flexibility and diversification.

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.

Nest site selection for five common birds and their coexistence in an urban habitat.

Many species of birds gradually adapt to urbanization and colonize cities successfully. However, their nest site selection and competitive relationship in an urban community remain little known. Understanding the impact of urbanization on birds and the competitive relationship has important implications for the conservation and management of wildlife in urban ecosystems. Here, we undertook a systematic study to quantify nests in all species of birds in an urbanizing area of Nanchang, China. A total of 363 nests were detected in surveys including 340 nests of 16 bird species and 23 unidentified species nests. We mainly analyzed 5 dominant breeding birds with a sample size of >10 during the two breeding seasons (From April to July in 2016 and 2017), which included the light-vented bulbul, Chinese blackbird, scaly-breasted munia, spotted dove and grey-capped greenfinch. Most birds (93.66%) nested in the tree of artificial green belts, which seems to be the best breeding habitat for urban birds. Our results suggested that birds' breeding success relies on the trade-off between the benefit and the expense of specific stresses from habitats. The nest site selection of birds is also affected by the life habit of urban predators. Furthermore, competition among species can influence their distributions and utilization of environmental resources when birds nest in cities. We confirmed that the niche differentiation of five bird species in an urban environment makes them coexist successfully by utilizing various resources.

Bi-parentally Inherited Genetic Evidence for Male-Biased Dispersal in Common Moorhen (Gallinula chloropus).

Dispersal is a life history trait that has relevant effect on both the dynamics and the genetics of species and sex-biased dispersal depends on how resource competition affects each of the sexes. In this study, a total of 210 blood samples including 121 Common Moorhen (Gallinula chloropus) females and 89 males were collected from 18 diverse areas during the breeding season. Based on 8 microsatellite markers analyses, we found that the most genetic diversities from female populations were higher than those from the males, where only 2 male individuals were identified as the long-distance dispersal. Analyses of sex-biased dispersal conducted over all sampling sites indicated that mAI (female mAI = 0.195, male mAI = - 0.265, P = 0.01), FST (female FST = 0.045, male FST = 0.026, P = 0.020), and r (female r = 0.118, male r = 0.064, P = 0.010) in females were all significantly higher than those in males at the 0.05 level, which suggested a male-biased dispersal pattern in this species. Our Mantel test results suggested a significant isolation-by-distance pattern for females but not for males, which corresponded to the more frequent dispersal and gene flow in males than in females. This dispersal pattern could be explained by the special life history trait and mating system that Common Moorhen pair formation occurs before they leave the flock in the spring to establish territories and its females initiate courtship more frequently than males and compete with each other to pair with small males with large fat reserves. The philopatric female could benefit most from knowledge of a particular area because they may win more intrasexual competitions in the breeding season and be able to produce more offspring if they are familiar with the local resources.

Low Genetic Diversity and Low Gene Flow Corresponded to a Weak Genetic Structure of Ruddy-Breasted Crake (Porzana fusca) in China.

The Ruddy-breasted Crake (Porzana fusca) is an extremely poorly known species. Although it is not listed as globally endangered, in recent years, with the interference of climate change and human activities, its habitat is rapidly disappearing and its populations have been shrinking. There are two different life history traits for Ruddy-breasted Crake in China, i.e., non-migratory population in the south and migratory population in the north of China. In this study, mitochondrial control sequences and microsatellite datasets of 88 individuals sampled from 8 sites were applied to analyze their genetic diversity, genetic differentiation, and genetic structure. Our results indicated that low genetic diversity and genetic differentiation exit in most populations. The neutrality test suggested significantly negative Fu's Fs value, which, in combination with detection of the mismatch distribution, indicated that population expansion occurred in the interglacier approximately 98,000 years ago, and the time of the most recent common ancestor (TMRCA) was estimated to about 202,705 years ago. Gene flow analysis implied that the gene flow was low, but gene exchange was frequent among adjacent populations. Both phylogenetic and STRUCTURE analyses implied weak genetic structure. In general, the genetic diversity, gene flow, and genetic structure of Ruddy-breasted Crake were low.

Complete mitochondrial genome of Porzana fusca and Porzana pusilla and phylogenetic relationship of 16 Rallidae species.

The complete mitochondrial genome sequences of Porzana fusca and Porzana pusilla were determined. The two avian species share a high degree of homology in terms of mitochondrial genome organization and gene arrangement. Their corresponding mitochondrial genomes are 16,935 and 16,978 bp and consist of 37 genes and a control region. Their PCGs were both 11,365 bp long and have similar structure. Their tRNA gene sequences could be folded into canonical cloverleaf secondary structure, except for tRNASer (AGY), which lost its "DHU" arm. Based on the concatenated nucleotide sequences of the complete mitochondrial DNA genes of 16 Rallidae species, reconstruction of phylogenetic trees and analysis of the molecular clock of P. fusca and P. pusilla indicated that these species from a sister group, which in turn are sister group to Rallina eurizonoides. The genus Gallirallus is a sister group to genus Lewinia, and these groups in turn are sister groups to genus Porphyrio. Moreover, molecular clock analyses suggested that the basal divergence of Rallidae could be traced back to 40.47 (41.46‒39.45) million years ago (Mya), and the divergence of Porzana occurred approximately 5.80 (15.16‒0.79) Mya.

The complete mitochondrial genome of Himalayan Snowcock (Tetraogallus himalayensis).

We reported here the first complete sequences of mitogenome of Tetraogallus himalayensis obtained by next generation sequencing methods. The assembled mitogenome is a 16 692 bp circle, comprising of 13 protein-coding genes, two rRNA genes (12S rRNA and 16S rRNA), 22 tRNA genes, and one control region. The resultant phylogenetic tree supported T. himalayensis and T. tibeanus are sister taxon, and Tetraogallus with Alectoris and coturnix formed a monophyletic group.

Intercontinental genetic structure and gene flow in Dunlin (Calidris alpina), a potential vector of avian influenza.

Waterfowl (Anseriformes) and shorebirds (Charadriiformes) are the most common wild vectors of influenza A viruses. Due to their migratory behavior, some may transmit disease over long distances. Migratory connectivity studies can link breeding and nonbreeding grounds while illustrating potential interactions among populations that may spread diseases. We investigated Dunlin (Calidris alpina), a shorebird with a subspecies (C. a. arcticola) that migrates from nonbreeding areas endemic to avian influenza in eastern Asia to breeding grounds in northern Alaska. Using microsatellites and mitochondrial DNA, we illustrate genetic structure among six subspecies: C. a. arcticola,C. a. pacifica,C. a. hudsonia,C. a. sakhalina,C. a. kistchinski, and C. a. actites. We demonstrate that mitochondrial DNA can help distinguish C. a. arcticola on the Asian nonbreeding grounds with >70% accuracy depending on their relative abundance, indicating that genetics can help determine whether C. a. arcticola occurs where they may be exposed to highly pathogenic avian influenza (HPAI) during outbreaks. Our data reveal asymmetric intercontinental gene flow, with some C. a. arcticola short-stopping migration to breed with C. a. pacifica in western Alaska. Because C. a. pacifica migrates along the Pacific Coast of North America, interactions between these subspecies and other taxa provide route for transmission of HPAI into other parts of North America.

Phylogeography of Chinese bamboo partridge, Bambusicola thoracica thoracica (Aves: Galliformes) in south China: inference from mitochondrial DNA control-region sequences.

Chinese bamboo partridge (Bambusicola thoracica thoracica), an endemic subspecies of south China, distributes in mountainous areas that were affected by climate changes throughout the Pleistocene. We investigated the potential impact of cyclical Pleistocene climate changes on phylogeographic patterns using 1140 nucleotides of mitochondrial DNA (mtDNA) control-region from 180 individuals sampled from 13 populations of the partridge. We found 50 haplotypes defined by 39 polymorphic positions. Phylogenetic analyses revealed two robustly supported clades. There was a significant genetic differentiation among the populations with little gene flow. Refugia were identified in the southwestern mountains and Luoxiao Mountains in China, implying that topographic complexity played a substantial role in providing suitable habitats for the partridge during cold periods. Results from the mismatch distribution and neutrality test analysis suggested a range expansion of the two clades. The mtDNA marker suggested the existence of a geographical structure among Chinese bamboo partridge populations, resulting from the synergistic affect of Pleistocene climatic variations.

Phylogeography of Tibetan snowcock (Tetraogallus tibetanus) in Qinghai-Tibetan Plateau.

Data from eight microsatellite loci were used to infer the evolutionary and past demographic processes in 97 Tibetan snowcocks sampled from eight different geographical locations on the Qinghai-Tibetan Plateau. Analysis of the microsatellite DNA markers indicated that Tibetan snowcock on the plateau were geographically structured, and that phylogenetic analyses identified three phylogroups, namely those from Xunhua, the Qilian Mountains and all others. The use of Bayesian Clustering and Population Assignment analyses of the microsatellite genotypes revealed clear differentiation among the eight sampled groups of Tibetan snowcock, indicating strong isolation of these sub-populations. Therefore, we suggested that the distribution pattern of Tibetan snowcock observed today resulted from adaptation to the climatic conditions and glacial cycles on the Qinghai-Tibetan Plateau. In addition, BOTTLENECK analysis indicated that Tibetan snowcock had recently passed through evolutionary bottlenecks. These results suggested that effective conservation measures should be undertaken to protect Tibetan snowcock from an increased probability of extinction.

[Egretta garzetta as a bioindicator of environmental pollution in Tai Lake region].

There were four species of Ardeidae in Tai Lake. The dominant vegetations in the habitat were Pinus massoniana, Cinnamomum hupehanum, Quercus acutissema, Ulmus prmila and Myrica rubra, which were suitable for Egretta garzetta to make nests. The area of the habitat was about 7 hm2, where there were totally 4200 Egretta garzetta nests with the density of 0.38 nest per tree in average. Studies on Egretta garzetta breeding ecology showed that the incubating time was 19-21 days, the average egg weight was 23.9 +/- 4.0 g(n = 41), and the average egg size was 44.5 +/- 4.1 mm x 32.6 +/- 4.9 mm(n = 41). The mean clutch size and brood size were 5.02(2-8) and 3.86(2-7), respectively, and the hatching rate was 84.25%. The measurements of Egretta garzetta nestling tarsus did not show any asymmetry (P > 0.05). Egretta garzetta fed mainly on small fish and shrimps in Tai Lake. The analysis results of Tai Lake samples showed that the pollutants including HCH, HCB, cyclodience, DDTs (DDT, DDE and DDD), PCBs, Cr, Hg and Pb in Egretta garzetta eggs were detected except Cd, and these pollutants accumulated through prey chain from sediments and preys to nestlings. Comparing samples from Tai Lake and those from Poyang Lake as relatively unpolluted area, only the concentration of DDTs residues was higher than 2 micrograms.g-1 in both lakes, and the other residues from Tai Lake like organochlorine insecticides, PCBs and heavy metals were all lower than those from Poyang Lake, and did not affect the development and breeding success of Egretta garzetta at present.