Background:The Black-necked Crane (Grus nigricollis)is an internationally threatened crane living on the plateau, mainly in winter, in the Yarlung Tsangpo River basin in Tibet,western China. In the past five years,som...Background:The Black-necked Crane (Grus nigricollis)is an internationally threatened crane living on the plateau, mainly in winter, in the Yarlung Tsangpo River basin in Tibet,western China. In the past five years,some economic development projects have been conducted in this area,posing potential threats to the wintering populations of the cranes and their habitats. Therefore, the current population dynamics of wintering Black-necked Cranes and habitat suitability in the Yarlung Tsangpo River basin were investigated. Methods: Twenty counties were surveyed using the line transect method in December 2017 and January 2018, and we recorded the location,flock size,number of individuals,habitat types and presence of human disturbance in which they occurred.We compared the results from the middle wintering period in this survey with those from 2014. Results: The highest number of cranes recorded was 8291,and the results showed that the cranes were mainly distributed in Lhaze, Namling, Samzhubze, and Lhunzub.A total of 577 and 495 flocks were recorded in the early and middle wintering periods, respectively. In the early wintering period,there were signi ficant differences in the number of individuals across the di fferent habitats,with crop stubble land and plowed land representing more than 30% of the total habitat utilization.In the middle wintering period, there were also signi ficant differences in the number of individuals, and the utilization of crop stubble land represented over 60% of the total. Conclusions: Wintering Black-necked Cranes mainly fed on spilled grains in stubble habitat after harvest. In the middle wintering period, some of the farmlands were plowed and irrigated,which resulted in food shortages in these areas,and the cranes tended to gather in mixed flocks of large size instead of as a single family.There were still considerable regional wintering populations decreases in Quxu,Nedong,and Sakya in 2018 compared with 2014,and these decreases were mainly due to some recently emerging threats,including farmlands being converted into areas of greenhouse cultivation,highway and railway construction, river dredging,the rapid development of the manufacturing and mining industries,and the lack of protection of important wintering sites.展开更多
Background: Understanding how overwintering birds choose foraging habitats is very important for conservation management. The overwintering Black-necked Crane(Grus nigricollis) feeds on crop remains in farmlands;thus,...Background: Understanding how overwintering birds choose foraging habitats is very important for conservation management. The overwintering Black-necked Crane(Grus nigricollis) feeds on crop remains in farmlands;thus, reasonable conservation management of this type of farmland that surrounds wetlands is critical for the overwintering populations of the Black-necked Crane;however, it is not clear how the Black-necked Crane chooses the foraging land in the farmland.Methods: A thorough field positioning survey of all foraging sites in farmland areas around the Caohai Wetland and a-sampling analysis of habitat selection by the Black-necked Crane were conducted during the winters from 20162017 and 2017-2018.Results: Multiple factors contributed to the selection of foraging habitat in farmlands, i.e., food factors(crop remains and tillage methods) > human disturbance factors(distance to road and settlement) > topography factors(slope aspect), listed according to the strength of influence. Additionally, Black-necked Cranes tend to choose farmland sites where there was no machine tillage, the crop remains were > 500 g/m^2, the distance to residences ranged from 100 to 500 m, the distance to roads ranged from 50 to 100 m, and the slopes exhibited western or eastern aspects. As the winters progressed, the volume of the edible crop remains declined, and the influences of the other main factors also changed, i.e., the factors of human disturbance(distance to road and settlement) became less important, while the effect of the food factor(crop remains) was strengthened. Thus, the foraging sites near the road became more important.Conclusion: The farming area surrounding the Caohai Wetland is very important for the overwintering Black-necked Crane. Food factors and human disturbance factors are the main factors that influence the choice of feeding ground.展开更多
Bird migration is a seasonal movement between breeding and wintering grounds.Opinions are widely divided on the reasons for this movement.According to biological data including:geographic distribution,reproductive phy...Bird migration is a seasonal movement between breeding and wintering grounds.Opinions are widely divided on the reasons for this movement.According to biological data including:geographic distribution,reproductive physiology,comparison of breeding and wintering habitats,geological data including Qinghai Tibetan Plateau uplift and Quatemary Period glaciation,it is inferred that bird migration is a survival mechanism,and that migration originated on the breeding grounds.展开更多
Based on the concepts of species and speciation,the speciation of Black necked Grane(Grus nigricollis) was discussed using bio geographic principles and some evidences suggest that Black necked Grane had a close re...Based on the concepts of species and speciation,the speciation of Black necked Grane(Grus nigricollis) was discussed using bio geographic principles and some evidences suggest that Black necked Grane had a close relationship with Red crowned Crane(Grus japonensis).The Qinghai Tibetan Plateau uplift may be the most important factor in allopatric speciation for Black necked Crane.展开更多
Background:Vigilance refers to the behavior of animals scanning their surroundings with a main purpose of antipredation.Whether vigilance can serve the function of anti-predation depends on its unpredictability,meanin...Background:Vigilance refers to the behavior of animals scanning their surroundings with a main purpose of antipredation.Whether vigilance can serve the function of anti-predation depends on its unpredictability,meaning instantaneous randomness,sequential randomness,and independence,the three assumptions from Pulliam model(J Theor Biol 38:419,1973).Here we tested two of these three assumptions in reproductive Black-necked Cranes(Grus nigricollis) in Tibetan Plateau:instantaneous randomness and sequential randomness.Methods:Observations were carried out in July and September of 2014,July and August in 2017 in Selincuo National Nature Reserve,Tibet,with the help of focal sampling method.For instantaneous randomness,we used Kolmogorov–Smirnov test for its negative exponential distribution;for sequential randomness,we used Run test,correlation analysis,and generalized linear model to see if an inter-scan and its previous scan were correlated.Results:Not similar to some recent studies,we did not find a significant predictable vigilance in this crane.Most inter-scan intervals(86/100,86.0%) passed negative exponential distribution test,meaning vigilance sequences with instantaneous randomness;most inter-scan intervals(91/100,91.0%) passed sequential random test,showing vigilance sequences were random organized.Conclusion:Our results suggest that keeping a vigilance pattern with unpredictability is beneficial to the survival of the Black-necked Cranes,which are facing with both cruel natural environments and high predation risks.展开更多
基金supported by the program from Forestry and Grassland Department of Tibet Autonomous Region
文摘Background:The Black-necked Crane (Grus nigricollis)is an internationally threatened crane living on the plateau, mainly in winter, in the Yarlung Tsangpo River basin in Tibet,western China. In the past five years,some economic development projects have been conducted in this area,posing potential threats to the wintering populations of the cranes and their habitats. Therefore, the current population dynamics of wintering Black-necked Cranes and habitat suitability in the Yarlung Tsangpo River basin were investigated. Methods: Twenty counties were surveyed using the line transect method in December 2017 and January 2018, and we recorded the location,flock size,number of individuals,habitat types and presence of human disturbance in which they occurred.We compared the results from the middle wintering period in this survey with those from 2014. Results: The highest number of cranes recorded was 8291,and the results showed that the cranes were mainly distributed in Lhaze, Namling, Samzhubze, and Lhunzub.A total of 577 and 495 flocks were recorded in the early and middle wintering periods, respectively. In the early wintering period,there were signi ficant differences in the number of individuals across the di fferent habitats,with crop stubble land and plowed land representing more than 30% of the total habitat utilization.In the middle wintering period, there were also signi ficant differences in the number of individuals, and the utilization of crop stubble land represented over 60% of the total. Conclusions: Wintering Black-necked Cranes mainly fed on spilled grains in stubble habitat after harvest. In the middle wintering period, some of the farmlands were plowed and irrigated,which resulted in food shortages in these areas,and the cranes tended to gather in mixed flocks of large size instead of as a single family.There were still considerable regional wintering populations decreases in Quxu,Nedong,and Sakya in 2018 compared with 2014,and these decreases were mainly due to some recently emerging threats,including farmlands being converted into areas of greenhouse cultivation,highway and railway construction, river dredging,the rapid development of the manufacturing and mining industries,and the lack of protection of important wintering sites.
基金following projects:National Natural Science Foundation of China(NSFC)(31860610,31400353)Provincial Key Science and Technology Project of Guizhou([2016]3022-1)+3 种基金Provincial Science and Technology Plan of Guizhou([2014]7682[2019]1068)Science and Technology Plan of Education Administration of Guizhou Province([2018]102[2015]354).
文摘Background: Understanding how overwintering birds choose foraging habitats is very important for conservation management. The overwintering Black-necked Crane(Grus nigricollis) feeds on crop remains in farmlands;thus, reasonable conservation management of this type of farmland that surrounds wetlands is critical for the overwintering populations of the Black-necked Crane;however, it is not clear how the Black-necked Crane chooses the foraging land in the farmland.Methods: A thorough field positioning survey of all foraging sites in farmland areas around the Caohai Wetland and a-sampling analysis of habitat selection by the Black-necked Crane were conducted during the winters from 20162017 and 2017-2018.Results: Multiple factors contributed to the selection of foraging habitat in farmlands, i.e., food factors(crop remains and tillage methods) > human disturbance factors(distance to road and settlement) > topography factors(slope aspect), listed according to the strength of influence. Additionally, Black-necked Cranes tend to choose farmland sites where there was no machine tillage, the crop remains were > 500 g/m^2, the distance to residences ranged from 100 to 500 m, the distance to roads ranged from 50 to 100 m, and the slopes exhibited western or eastern aspects. As the winters progressed, the volume of the edible crop remains declined, and the influences of the other main factors also changed, i.e., the factors of human disturbance(distance to road and settlement) became less important, while the effect of the food factor(crop remains) was strengthened. Thus, the foraging sites near the road became more important.Conclusion: The farming area surrounding the Caohai Wetland is very important for the overwintering Black-necked Crane. Food factors and human disturbance factors are the main factors that influence the choice of feeding ground.
文摘Bird migration is a seasonal movement between breeding and wintering grounds.Opinions are widely divided on the reasons for this movement.According to biological data including:geographic distribution,reproductive physiology,comparison of breeding and wintering habitats,geological data including Qinghai Tibetan Plateau uplift and Quatemary Period glaciation,it is inferred that bird migration is a survival mechanism,and that migration originated on the breeding grounds.
文摘Based on the concepts of species and speciation,the speciation of Black necked Grane(Grus nigricollis) was discussed using bio geographic principles and some evidences suggest that Black necked Grane had a close relationship with Red crowned Crane(Grus japonensis).The Qinghai Tibetan Plateau uplift may be the most important factor in allopatric speciation for Black necked Crane.
基金financially supported by the National Natural Science Foundation of China(Nos.31360141,31772470,and No.J1103512)the West Light Foundation of Chinese Academy of Sciences(2015)the Project of National Biodiversity Observation Network-Bird(2015-2018)
文摘Background:Vigilance refers to the behavior of animals scanning their surroundings with a main purpose of antipredation.Whether vigilance can serve the function of anti-predation depends on its unpredictability,meaning instantaneous randomness,sequential randomness,and independence,the three assumptions from Pulliam model(J Theor Biol 38:419,1973).Here we tested two of these three assumptions in reproductive Black-necked Cranes(Grus nigricollis) in Tibetan Plateau:instantaneous randomness and sequential randomness.Methods:Observations were carried out in July and September of 2014,July and August in 2017 in Selincuo National Nature Reserve,Tibet,with the help of focal sampling method.For instantaneous randomness,we used Kolmogorov–Smirnov test for its negative exponential distribution;for sequential randomness,we used Run test,correlation analysis,and generalized linear model to see if an inter-scan and its previous scan were correlated.Results:Not similar to some recent studies,we did not find a significant predictable vigilance in this crane.Most inter-scan intervals(86/100,86.0%) passed negative exponential distribution test,meaning vigilance sequences with instantaneous randomness;most inter-scan intervals(91/100,91.0%) passed sequential random test,showing vigilance sequences were random organized.Conclusion:Our results suggest that keeping a vigilance pattern with unpredictability is beneficial to the survival of the Black-necked Cranes,which are facing with both cruel natural environments and high predation risks.
