Seasonal migration patterns of Siberian Rubythroat (Calliope calliope) facing the Qinghai-Tibet Plateau

Abstract

Background Small songbirds respond and adapt to various geographical barriers during their annual migration. Global flyways reveal the various migration strategies in response to different geographical barriers, among which are high-elevation plateaus. However, few studies have been focused on the largest and highest plateau in the world, the Qinghai-Tibet Plateau (QTP) which poses a significant barrier to migratory passerines. The present study explored the annual migration routes and strategies of a population of Siberian Rubythroats (Calliope calliope) that breed on the north-eastern edge of the QTP. Methods Over the period from 2021 to 2023, we applied light-level geolocators (n = 13), archival GPS tags (n = 45), and CAnMove multi-sensor loggers (with barometer, accelerometer, thermometer, and light sensor, n = 20) to the breeding population of Siberian rubythroat on QTP. Here we describe the migratory routes and phenology extracted or inferred from the logger data, and used a combination of accelerometric and barometric data to describe the elevational migration pattern, flight altitude, and flight duration. Results Both GPS locations and positions derived from pressure-based inference both revealed that during autumn, the migration route detoured from the bee-line between breeding and wintering grounds, leading to a gradual elevational decrease. The spring route was more direct, with more flights over mountainous areas in western China. This different migration route during spring probably reflects a strategy for a faster migration, which corresponds with more frequent long nocturnal migration flights and shorter stopovers during spring migration than in autumn. The average flight altitude (2000 m above sea level) was correlated with ground elevation but did not differ between the seasons. Conclusions Our finding indicates the strong impact of the Qinghai-Tibet Plateau on shaping passerine migration strategies. We hereby call for more attention to the unexplored central-China flyway to extend our knowledge on the environment-migration interaction among small passerines.