Population Ecological Characteristics And Habitat Assessment Of Asian Elephant (Elephas Maximus) In Nangunhe National Nature Reserve,China

There only remains about 300 wild Asian elephants(Elephas maximus)in China,scattered in several reserves and its surroundings in southern and southwestern Yunnan province.Among them,the Nangunhe National Nature Reserve(NNNR)in Lincang city has the smallest population size,and the distribution area is only 70 km~2.It faces a series of survival threats brought by habitat reduction,fragmentation and the isolation of the elephant population itself.Therefore,it is crucial to know the population size,density,sex ratio,age structure and body condition of the Asian elephant in this reserve,to monitor and predict the suitable habitat.In this paper,the non-invasive automatic infrared camera technology was used to estimate the population of Asian elephant.52 cameras were installed in the western core area of Cangyuan County of NNNR for field investigation during February to May 2018.During the survey period,working days for each camera ranged from 73 to 129 days,for a total of 5,942 days.A total of 70,902 photos and videos were obtained,which including 5,207 Asian elephants with a shooting rate of 7.34%(the total number of images of Asian elephants/the total number of images).Individual identification was carried out through the massive images,and 12 individuals(a family of 9 individuals and 3 solitaries)were finally identified,including 3 adult males,3 adult females,1 sub-adult male,2 juvenile males,2juvenile females and 1 male calf.The male to female ratio of the population was 1:1.4,the age structure was inverted pyramid,with a decrease tendency of this population.A population density of 5.32±1.56elephants/100 km~2 was estimated by using Spatially Explicit Capture Recapture(SECR)models.The health condition of this population was assessed by using an 11-points scale of Body Condition Scoring(BCS)method which showed that this population had a medium body condition with an average of 5.75(n=12,range 2-9).It was found only 33.3%of the individuals were in good body condition,50%were in normal and the remaining 16.7%were in poor body condition.Camera traps were placed at altitudes ranged from 517m to 917 m.Nearly half of the cameras(25)were located in the area with flat terrain,14 cameras were located in the area with moderate slope,and only 13 cameras were located in the area with steep slope.Thirty cameras,accounting for 57%of the total number of cameras,were installed in broad-leaved forest,only one quarter(13 cameras)were installed in the mixed bamboo forest,7 cameras were installed in the bamboo forest,and the remaining2 cameras were installed near the pine forest and the brushwood.The 24 cameras were set near rivers of tributaries with the distances of less than 100 m.Occupancy model showed that elephants preferred near the river,high shrub cover,high total volume of vegetation(TVV)and moderate slope areas;MAXENT model indicated that the environment factors affecting the habitat suitability were altitude,distance from the village,slope and land use.With the elevation increasing,the slope becomes steeper and the habitat suitability decreases.Within a range 2 km,the area far from the village was the habitat preference area of Asian elephants,and the habitat suitability increased.Asian elephants were most likely to appear in natural broadleaf forests,followed by bamboo forests and thickets.Suitable prediction map showed the west side of core zones were suitable for them,roll around in the south river basin.And there few suitable habitats scattered outside the reserve.The survival status of small isolated Asian elephant population,which remains on such a small“island”in NNNR,is worrying because of its declining age structure,small population and general health status.The species is at risk of extinction in the wild without proper artificial intervention.In this study,the basic information of population ecology was obtained through camera traps,and the individual database of population was established,which will provide scientific data support for the management organization to formulate targeted protection measures.