Distribution of geographically restricted and evolutionarily unique species and its underlying drivers is key to understand evolutionary patterns and conserve biodiversity. However, few studies have simultaneously tested the associations of biotic interactions, environmental heterogeneity, contemporary and paleo-climate, species traits, and human activities with patterns of bird endemism. Here, we quantified the geographic distribution patterns and drivers of species and phylogenetic endemism of 1127 bird species in China. The results showed that species and phylogenetic endemism of Chinese birds was higher in western China, especially in northwestern and southwestern China. Higher plant species richness, altitudinal range, net primary productivity, and lower temperature seasonality were associated with higher species and phylogenetic endemism. In addition, altitudinal range and net primary productivity can also indirectly influence species and phylogenetic endemism by directly affecting plant species richness. This may be because greater altitudinal range could foster more diverse habitats, and higher net primary productivity could ensure abundant food resources. Notably, species and phylogenetic endemism were also negatively associated with clutch size and cropland area. These findings identify that northwestern and southwestern China have the highest evolutionary and biogeographical uniqueness of bird assemblages, and provide insights into the evolutionary underpinnings of biogeographical patterns in Chinese birds. Meanwhile, it is crucial to conserve plant diversity, focus on groups with specific traits, and reduce human activities to better protect bird diversity.

Waterbirds are vital for wetland ecosystems, but climate change and human activities are harming these habitats globally, reducing biodiversity and threatening waterbird survival. In China, wetlands in humid and arid regions face quite different threats, necessitating targeted conservation strategies. However, few studies have assessed the relative roles of various drivers in determining geographical patterns of alpha and beta diversity of wetland waterbirds in different regions, particularly from the perspectives of taxonomic, phylogenetic and functional diversity. This study aims to connect climate and landscape variables with waterbirds diversity in 71 wetlands across China's humid and arid regions. The results showed that mean annual temperature was negatively associated with taxonomic diversity but positively correlated with phylogenetic structure. Phylogenetic and functional diversity was significantly associated with paleoclimate change. Additionally, patch richness was positively correlated with taxonomic diversity and functional structure, but negatively correlated with phylogenetic diversity and structure. Notably, taxonomic and phylogenetic beta diversity was dominated by turnover, while functional beta diversity was dominated by nestedness-resultant components. Total edge and patch density were significantly correlated with waterbird beta diversity. In addition, arid regions showed higher turnover in taxonomic and phylogenetic diversity compared to humid regions. Compared to arid regions, humid regions had consistently higher nestedness-resultant components in the three diversity dimensions and higher turnover in functional beta diversity. These findings indicated that while climate variables are important for waterbird diversity patterns, wetland's landscape characteristics could also play significant roles. In addition, conservation of Chinese wetland bird diversity should consider unique strategies for different biodiversity dimensions as well as for different regions.

Biological specimens are fundamental for taxonomy and flora/fauna research. More importantly, they also play crucial roles in recording environmental impacts on morphology and behavior, which is vital for biodiversity research and conservation. However, there are few systematic studies on the patterns and drivers of bird specimen number at regional scales. This study is the first attempt to examine the relationships between bird specimen number and species traits as well as climate niche breadth in China, aiming to answer two questions: 1) how do species' temperature niche breadth and precipitation niche breadth influence specimen number? 2) which trait is most associated with bird specimen number? The associations between bird specimen number and explanatory variables were examined using ordinary least squares, generalized linear models, phylogenetic generalized linear mixed models, and multiple comparisons. The results showed that Muscicapidae was the family with the highest specimen number, and Passeriformes was the order with the highest specimen number. Bird specimen number significantly increased with larger temperature niche breadth and precipitation niche breadth. Specimen number was also positively associated with geographic range size, habitat specificity, hunting vulnerability and clutch size, but negatively associated with body size. These findings suggest that future bird specimen collection should pay more attention to birds with limited ecological niches, large body sizes, and small clutch sizes. This research enhances the use of bird specimen data to study and preserve biodiversity.