Altitudinal migration behavior patterns of birds on the eastern slope of Mt.Gongga,China

Many bird species in montane regions exhibit altitudinal migration behavior;however,altitudinal migration of birds is still understudied,especially in Asia.Mt.Gongga(7556 m) is the highest peak of the Hengduan Mountains in Southwest China.The steep elevation gradient and the high bird diversity make the eastern slope of Mt.Gongga(Hailuo Valley) an ideal place for studying the altitudinal migration behavior patterns of birds.We synchronously recorded the local bird diversity,temperature and humidity at two sites(1800 and 3000 m a.s.l.) during three migration seasons from September 2020 to June 2021 to identify birds exhibiting altitudinal migration behavior.During our surveys,we recorded 146 bird species in total and 20 passerine bird species were altitudinal migrants according to our altitudinal migration formula.Among those 20 altitudinal migrant species,eight bird species displayed a typical altitudinal migration pattern(upward migration during the breeding season and downward migration during the non-breeding season).Moreover,temperature was correlated with the daily number of individuals(DNI) at each study site.Therefore,increasing temperatures possibly caused upward migration of birds(DNI decreased at 1800 m and increased at 3000 m) and vice versa.To further elaborate,the Rufousgorgeted Flycatcher(Ficedula strophiata),the species with the most prominent altitudinal migration behavior,initiated upward migration at a temperature of 11-12℃ at 1800 m and initiated downward migration at a temperature of 12-13℃ at 3000 m.Besides,humidity was positively correlated with the DNI.Therefore,increasing humidity(equals to increasing rainfall or snow) possibly caused downward migration of birds(DNI increased) and vice versa.Furthermore,bird species exhibiting a typical altitudinal migration behavior pattern are feeding on insects.Thus,the spatial and temporal changes of the invertebrate biomass might be an important ecological driver for the altitudinal migration of invertivorous(birds eating invertebrates) birds.This study provides fundamental data for the altitudinal migration of birds in the Hengduan Mountains and shows how altitudinal migration is seasonally dynamic across an elevational gradient in a subtropical mountain region.

Comparative analysis of the intestinal tract microbiota and feeding habits of five sympatric flycatchers

Gut microbiota and host interactions co-evolve and develop into stably adapted microbial communities and play vital roles in maintaining the health of organisms.Diet is supposed to be an important driver of differences in gut microbiota,but previous studies would commonly use literature depictions,which are essential but inaccurate,to explain the effects of diet on the gut microbiota of wild birds.In this study,we collected intestinal samples from five sympatric flycatchers to compare the gut microbial differences using bacterial 16S rRNA genes from Illumina MiSeq platform.Over 1,642,482 quality-filtered sequences from 1816S rRNA libraries were obtained and distinct compositions and diversities of gut microbiota were found in five flycatchers.Their gut microbiota is mainly from the four bacterial phyla of Proteobacteria,Firmicutes,Actinomycetes,and Bacteroidetes,but at the genus level showed a significant difference.Functional predictions revealed that the metabolic capacity of the gut microbiota of five flycatchers is greatly distinguished at KEGG level 3.And multiple food fragments showed a significant correlation with gut microbiota.Besides,the significant differences in the specific composition of the diets of the five insectivorous flycatchers indicated the differentiation of dietary niches.The study of the gut microbiota and feeding habits of sympatric flycatchers would increase the understanding of the gut microbial diversity of wild birds,and also improve our cognition of the co-evolution and co-adaptation within the host gut microbiota relations.

都江堰地区繁殖期鸟类多样性

都江堰地区位于生物多样性热点地区,具有丰富的鸟类多样性,但迄今仍缺乏全面的鸟类物种名录。本研究于2016年5月至2019年8月,在都江堰地区采用固定样线法开展了鸟类多样性调查,结合历史文献共记录该地区鸟类17目61科311种。其中留鸟184种(59.2%),夏候鸟68种(21.9%),冬候鸟35种(11.3%),旅鸟24种(7.7%);繁殖鸟类252种(81.0%);雀形目鸟类212种(68.2%);国家I级重点保护鸟类9种(2.9%),国家II级重点保护鸟类50种(16.1%),中国特有鸟类15种(4.8%)。研究发现,常绿-落叶阔叶混交林及灌丛中的鸟类物种最多,而常绿针叶林和竹林中的鸟类物种最少。都江堰地区鸟类群落丰富度的峰值出现在1,580-1,890 m海拔段,在1,890-2,200 m海拔段最低,呈现出单峰分布格局。作为生物多样性热点地区和旅游热点地区,都江堰今后应避免发展大规模单一的人工经济林,以更好地维系该地区丰富的鸟类多样性,并加强对该地区生物多样性的监测、研究和保护。