Ecological portraits: Mapping functional spectra and space characteristics of birds in China

The functions of wildlife species in ecosystems and their responses to environmental changes are mediated through their functional traits. By mapping the gradient across the diversity of bird ecological strategies (functional spectra) and quantifying the functional spaces of the focus taxon, we can better understand their ecological requirements and acquire critical information needed for developing effective conservation strategies. As one of the world’s 17 mega-diversity countries China harbors a highly diverse avian fauna. Using China’s 1445 bird species, we constructed a comprehensive dataset of their functional traits, encompassing morphological feature, dietary composition, fecundity and space utilization. The results showed that birds in China exhibited a clustered distribution pattern within the functional spectra and spaces. Specifically, terrestores, natatores, and raptators displayed relatively diverse strategies (low functional redundancy), indicating their high conservation priority. Compared to non-threatened species, the threatened species assessed by China’s Red List exhibited much lower functional redundancy. The total volume of the 4-dimensional functional space occupied by all bird species in China was 169.6 SD 4 , but only approximately 45 % is currently realized when compared to the two null models, displaying a non-uniform distribution pattern. Scenario analyses showed that, compared to randomized extinction, the loss of functional space would be significantly greater in an extinction scenario where there is no improvement in the species’ current threatened status. Bird species characterized by large body mass, narrow distribution range, small clutch size, and non-invertebrate diet are more vulnerable while facing future extinction risks. Our study, for the first time, quantitatively describes the ecological strategies of China’s avian fauna through an integrated cross-dimensional analysis and provides a solid foundation and valuable insights to future ecological studies and conservation policies.