Migration Patterns,Habitat Use Of Two Black-Necked Crane (Grus Nigricollis) Populations Revealed By Satellite Tracking

The Black-necked Crane(Grus nigricollis)is the only crane that lives on the plateau all its life.In recent years,the population has been threatened by increased human disturbance and habitat loss.From 2015 to 2016,five and seven Black-necked Cranes in Dashanbao wetland in Yunnan Province and Nyingchi Prefecture in Tibet autonomous region were attached with GPS-GSM transmitters,respectively.Based on satellite tracking data,we compared the migration patterns and habitat use of the RuoergaiDashanbao and Qinghai-Ningzhi Black-necked Crane populations.This research revealed the migration route of the Black-necked Cranes from Qinghai to Nyingchi for the first time.Three important migration stopover sites were identified for the Bai River in the Ruoergai population and the Basom Lake and Shazhuyu River in the Qinghai population.Migration period(spring: 4.2 ± 3.9 d;autumn: 7.0 ± 2.9 d)and migration distance(spring: 755.0 ± 64.8 km;autumn: 774.5 ± 48.0 km)of Ruoergai population were shorter than the migration period(spring: 8.7 ± 4.6 d;autumn: 30.0 ± 10.6 d)and migration distance(spring: 1182.5 ± 90.4 km;autumn: 1455.7 ± 138.0 km)of Qinghai population.The home range(95% KDE)and core area(60% KDE)of the tracked individuals were calculated by kernel density estimation.For Ruoergai population,the home range and core area of breeding individual in summer and winter are much smaller than that of non-breeding individuals.For Qinghai population,the home range and core area of breeding individuals in summer are much smaller than nonbreeding individuals;but the home range and core area of breeding individual in winter are larger than that of non-breeding individual.Based on the landcover data,the habitat use of two populations was compared.Black-necked Cranes prefer wetland and water type habitats.Grassland type habitats are preferred in summer and cultivated land type habitats are preferred in winter.The species distribution model was established based on the environmental factor data obtained from the public platform to rank the importance of environmental factors in habitat selection.Altitude has a great influence on the habitat selection of Black-necked Crane in both summer and wintering periods,the factors related to slope and precipitation have a great influence on the habitat selection in summer,and the factors related to temperature have a great influence on the habitat selection in winter.The research results lay a foundation for further exploration about the migration behavior and habitat use of Black-necked Cranes and provide references for future scientific research and conservation management.