Ecological Traits Affect The Seasonal Migration Patterns Of Resident Birds Along A Subtropical Altitudinal Gradient

Abstract Background: Altitudinal bird migration involves seasonal shifts up and down the altitude gradient annually. Asia as the place with the largest number of altitudinal migrants, has quite few related studies, especially for montane and temperate avifaunas.Method: To explore the potential drivers of seasonal altitudinal migration for birds in the middle of Hengduan Mountains, we conducted a two-year investigation on breeding and non-breeding season bird communities at eight altitude sections in the Gongga Mountains. Then, we examined the altitudinal migration patterns and relationships between seasonal distribution shifts and species’ traits, of 20 species with sufficient data recorded in both seasons.Results: We found that a large proportion of resident birds underwent altitudinal migration and showed 3 patterns (downslope shift, upslope shift, no shift). Species’ seasonal distribution shifts were mainly correlated with territoriality, nest height, diet, and temperature tolerance range. The species nesting in scrub and omnivores were more likely to present a downhill movement in the non-breeding season. In addition, territorially weaker species migrated more widely and performed multiple patterns. Notably, HWI dominated upslope shifts in altitudinal migration.Conclusion: Studying the seasonal altitudinal migration patterns of birds is essential to understanding their distributional responses to seasonal changes in climate (energy), which has important conservation implication for avian biodiversity. These results further consolidate the study of seasonal altitudinal migration in montane birds and verify that body mass is not correlated with altitudinal migration. This could be used to bridge existing knowledge gaps that currently impeding effective conservation.