Spatio-temporal distribution patterns and ecological correlates of new mammal records in China

Species' geographic distributions are central to research in biogeography, macroecology, and conservation biology. However, incomplete or inaccurate knowledge about their spatiotemporal ranges—known as the Wallacean shortfall—hampers our understanding of biodiversity patterns and their ecological and evolutionary processes. In this study, we systematically reviewed 192 papers that reported new distribution records of China’s mammals from 2001 to 2023 at the national and provincial levels, covering 150 species in 26 families across 7 orders. We examined the taxonomic, spatiotemporal, and biogeographic characteristics of these newly recorded species. We used Bayesian Phylogenetic Generalized Linear Mixed Models (PGLMM) to assess how intrinsic traits (e.g., body size) and extrinsic factors (e.g., climatic conditions) influenced the likelihood of discoveries and partial Poisson regressions to evaluate how species-level attributes, environmental conditions, and socio-economic factors shaped the number of newly recorded species across provinces. Our results showed that Chiroptera (n=69), Eulipotyphla (n=26) and Rodentia (n=23) had the highest number of new occurrence records. Among provinces, Yunnan (n=31), Guangdong (n=22), and Xizang (n=18) yielded the most newly recorded species. The amount of annual discoveries varied and peaked between 2017 and 2021. The Western Mountain and Plateau (n=39) and the East Hilly Plain (n=33) zoogeographic subregions had the greatest number of newly recorded species, including two new records extending into historically unrecognized zoogeographic realms. Notably, 61 (40.7%) newly recorded species were found to extend towards the north or northeast of their known ranges, and 32 (21.3%) eastward, mainly due to the sampling bias. Smaller-bodied species and those with broader habitat ranges are more likely to yield new records, and the total number of new records was positively correlated with regional species richness and current survey efforts (r > 0.5, p < 0.05). These findings expand the known mammal distributions in China and provide essential data for mitigating the Wallacean shortfall and guiding future conservation efforts. Our findings indicate that intensified survey efforts are urgently needed in biodiversity-rich, underexplored regions, particularly focusing on small-bodied and data-deficient taxa and that timely updates and data-sharing of distribution information are essential to enhance our understanding of biodiversity distribution dynamics and inform conservation strategies.