Does nest occupancy by birds influence the microbial composition?

Nest microbiota plays a vital role in the breeding and development of birds, which not only provides protection to bird hosts but also negatively affects the host. At present, it is unclear whether the composition of the microbes in the nests is affected by nesting. For this reason, we hung artificial nest boxes to simulate the natural nesting environment and combined 16S rRNA and ITS high-throughput sequencing technology to further study the differences in microbial composition and richness between used nests and control nests of Japanese tits (Parus minor). The study found that the bacteria in used nests and control nests showed significant differences at the phylum level (p < 0.05). It is also worth noting that the predominant bacteria in used nests were Proteobacteria (51.37%), Actinobacteria (29.72%), Bacteroidetes (6.59%), and Firmicutes (3.82%), while the predominant bacteria in control nests were Proteobacteria (93.70%), Bacteroidetes (2.33%), and Acidobacteria (2.06%). Both used nests and control nests showed similar fungi at the phylum level, which consisted mainly of Ascomycota and Basidiomycota, although significant differences were found in their relative abundance between both groups. The results of alpha diversity analysis showed significant differences in bacteria between the two groups and not in fungi. However, the beta diversity analysis showed significant differences between both bacteria and fungi. In summary, our results showed that the used nests had a higher abundance of beneficial microbiota and a lower presence of pathogenic microbiota. Therefore, we speculate that birds will change the characteristics of the nest microbial composition in the process of nest breeding to ensure their smooth reproductive development.

An improved comprehensive model for assessing the heavy metals exposure towards waterbirds: A case report from Black-necked cranes (Grus nigricollis) in Caohai Wetland, China.

Heavy metal contamination poses a significant environmental threat to wildlife on global scale, making accurate assessment of exposure risk crucial for conservation efforts, particularly for vulnerable species. Existing risk assessment models have been widely used, but their construction process lacks comprehensive considerations. In this study, we constructed an optimized health risk assessment model based on the well-established "Liu's model" and "ADI model", and applied the pollution allocation factor (AF) to accurately assess the risk of heavy metal exposure to wildlife. Our model was applied to assess exposure risk of heavy metal for the black-necked crane(Grus nigricollis), a flagship species in the alpine wetland ecosystem of Caohai Wetland. Soil, plant and black-necked crane fecal samples were collected from the Caohai Wetland and surrounding areas in Guizhou, China. We revealed varying degrees of As, Cd, Cr, Ni, Pb, and Zn contamination in soil and plants from different habitats, exceeding the background or plant limit values. This indicated that the black-necked crane and other waterbirds living in Caohai Wetland are suffering with the multi-elemental heavy metal contamination, especially in the gutterway and grassland. The exposure dose of As, Cd, Cr, Ni, Cu, and Zn toward black-necked cranes differed significantly in soil and plant pathways (P < 0.05). As, Cd, Cu, and Zn were mainly derived from plants consumption, while Cr and Ni originated from soil. Considering the contribution of soil and plant pathways to heavy metal exposure in black-necked cranes, the exposure doses of each elements calculated via food intake accounted for over half of the exposure calculated via feces (AF>0.5). The risk assessment model identified Cr and Pb were the highest risk elements for black-necked cranes, with exposure risk simulated through feces exceeding those through food. These findings suggested that current Liu's model may underestimate the effects of other pathways and medium. Therefore, we proposed a more comprehensive and accurate model for evaluating the exposure risk of black-necked cranes, incorporating AF to quantify the contribution of risk sources to black-necked cranes and understand their overall health risk. This model can serve as a useful tool for the conservation and habitat quality improvement of the black-necked cranes and other waterbirds.

The Food Niche Overlap and Interspecific Relationship between the Sympatric Tibetan Macaque and Grey Snub-Nosed Monkey.

Assessing the trophic niche and interspecific relationships between related species and determining how the species maintain differences in nutritional niches while coexisting in the same area are important topics in ecological research. Therefore, exploring the mechanism of food resource utilization, competition and coexistence among species distributed in the same region is important. In this study, we used fecal samples and metagenome sequencing technology to study the plant feeding habits and coexistence mechanisms of Tibetan macaques (Macaca thibetana) and grey snub-nosed monkeys (Rhinopithecus brelichi) within the same area. In the winter of 2020, we collected a total of 40 fecal samples from Tibetan macaques and grey snub-nosed monkeys; of those, 29 samples were considered valid and were analyzed using DNA metabarcoding. The results showed that in winter, Tibetan macaques consumed plants from 117 families and 184 genera, whereas grey snub-nosed monkeys consumed plants from 109 families and 165 genera. Diversity analysis revealed that there was a significant difference in the food composition of Tibetan macaques and grey snub-nosed monkeys. Tibetan macaques had a broader food niche width than grey snub-nosed monkeys at the family and genus levels. In winter, the food niches of Tibetan macaques and grey snub-nosed monkeys almost entirely overlapped (0.99). Our research provides detailed dietary data for Tibetan macaques and grey snub-nosed monkeys and valuable information that can aid in conservation efforts targeting these species.

Winter Dietary Analysis Reveals the Foraging Differences of Wild Boar (Sus scrofa) in Different Regions of a Karst Mountainous Area.

Wild boars (Sus scrofa) are extremely common in southern China, but little study has been conducted regarding reporting the dietary habits of wild boars using high-throughput sequencing technology, especially in karst areas, due to the difficulty in obtaining stomach contents of wild boars. In our study, the stomach contents of 14 wild boars in southern China were analyzed by DNA metabarcoding. The results showed that there were 153 genera, 93 families, and 48 orders of plant food sources for wild boars. The main plant food component were Cissus, Dioscorea, Quercus, Actinidia, and Houttuynia. The most numerous taxa of animal food sources were Elaphodus, Amynthas, Chonaphe, Rattus, and Tanytarsus. It is noteworthy that Elaphodus cephalophus were detected in most of the stomach samples, accounting for a large portion of animal food sources. The results showed that there were significant differences in the diets of wild boars in different regions; however, no significant differences were noted between male and female wild boars. Our study revealed the dietary preference of wild boars under the special forest conditions in the mountainous area of southwest China, as well as the relationship between the dietary habits of wild boars and their habitats from the perspective of resource utilization, thus providing a key scientific basis for the prevention and control of wild boars, along with resource protection.

Gut microbiota and fecal metabolites in captive and wild North China leopard (Panthera pardus japonensis) by comparsion using 16 s rRNA gene sequencing and LC/MS-based metabolomics.

BACKGROUND: Gut microbes significantly contribute to nutrient digestion and absorption, intestinal health and immunity, and are essential for the survival and environmental adaptation of wild animals. However, there are few studies on the gut microbiota of captive and wild North China leopard (Panthera pardus japonensis). RESULTS: A total of 10 mainly bacterial phyla were identified in the fecal microbiota of North China leopard, Lachnoclostridium (p = 0.003), Peptoclostridium (p = 0.005), Bacteroides (p = 0.008), Fusobacterium (p = 0.017) and Collinsella (p = 0.019) were significantly higher than those of wild North China leopard. Distinct differences in the fecal metabolic phenotypes of captive and wild North China leopard were found, such as content of l-methionine, n-acetyl-l-tyrosine, pentadecanoic acid and oleic acid. Differentially abundant gut microbes were associated with fecal metabolites, especially the bacteria in Firmicutes and Bacteroidetes, involved in the metabolism of N-acetyl-L-alanine and D-quinovose. CONCLUSION: This study reports for the first time the differences in gut microbiota abundance between captive and wild North China leopard, as well as significant differences in fecal metabolic phenotypes between two groups.