Foraging Selection Strategy Of Giant Panda(Ailuropoda Melanoleuca) At Feeding Plot In Winter Habitat

Winter is the worst time of year for giant panda(Ailuropoda melanoleuca)to obtain food,the environmental and food quality of the winter habitat is important for the survival and reproduction for giant pandas,and will largely determine the population density in the area where giant pandas are located.Predecessors have already done lots of research on foraging strategy of giant pandas,giving more prominence on foraging strategy of giant pandas under different seasons,but relatively few in-depth studies on foraging selection in winter when the pandas face the largest environmental pressure in one year.In addition,the existing studies focus more on the local scale and regional scale,but the foraging strategy of giant pandas on the fine scale is less explored.In order to better understand the foraging selection of giant pandas,this paper explored in depth that how giant pandas adopt foraging strategy in winter at a fine scale to overcome the nutritional challenges they face.With the help of GPS tracking technology,the field investigation was carried out on thirteen ravines at the jurisdiction of Sanguanmiao protection station,Foping National Nature Reserve(FNNR),Shaanxi province from October 2018 to March 2019.The feeding plots of five wild giant pandas(three giant pandas 1 #,2 # and 3 # with radio collars and two unknown giant pandas unknown-1# and unknown-2#)were investigated.and 64 samples were collected at the same time.We analyzed the habitat characteristics of giant pandas at feeding plots and relationship among macronutrients of bamboo at feeding plots through a geometric analysis by the mixed right-angled triangle model(RMT)in order to find out the connection between the habitat characteristics and nutritional status.And we further considered the optimized foraging selection strategy of giant panda in winter.The main research conclusions are as follows:1.In winter,the selection of feeding plot by giant pandas may be related to the slope of the feeding plot,canopy density of trees,water source distance and distance from the passage.The food availability in Wafanggou and Paifanggou is better than that in other areas.Giant pandas like to forage on gentle slopes or gullies with tree canopy density of 41 %?60 % and water source distance of 0?100 m.2.The five pandas showed different selectivity on the basal diameter,height and age of bamboo at a fine scale.Mainly displays in: basal diameter,1# liked to eat strong one-year leaves of Bashania fargesii(here in after referred to as B.bamboo,B.leaf and B.stem for short),2# liked to eat strong one-year and two-year B.leaves,3# liked to eat strong one-year and multi-year B.leaves,unknown #-1 selected to eat strong two-year and multi-year B.leaves and refused to eat one-year B.leaves,unknown #-2 liked to eat strong B.leaves of all ages.In terms of height,both 1# and 2# preferred to eat one-year and two-year B.leaves with moderate height and low multi-year B.leaves,3# preferred to eat low B.leaves,unknown #-1 prefer to eat low multi-year B.leaves,and unknown #-2 preferred to eat low B.leaves of all ages.All the five individuals showed a similar pattern in the height selection,that is,they all preferred to eat low leaves of multi-year B.bamboos.This is mainly due to the relatively large biomass of bamboo leaves,which is conducive to the nutrition and energy acquisition per unit feeding time.In terms of age,1#,2#,3# and unknown #-2 all showed a preference for eating one-year and two-year B.bamboo,but not multi-year.While unknown #-1 preferred two-year B.bamboo,but not multi-year,and refused one-year B.bamboo.In winter,pandas prefer one-year and two-year B.bamboo,but do not like multi-year B.bamboo.In addition,from the beginning of winter to the end of winter,the food intake of one-year B.bamboo decreases gradually,while that of two-year and multi-year increases gradually,which is closely related to the availability of food.3.There were significant differences in the nutritional content of all kinds of food.Crude protein content of B.leaves in all 13 feeding plots was 14.31 %?24.25 %,and crude protein content of B.stems was 1.28 %?5.10 %.In most feeding plots,crude protein content of one-year and two-year B.leaf and B.stem was higher than that of multi-year B.bamboo.Other nutritional indexes: crude fat(B.leaf 3 %?6 %,B.stem 2 %?7 %),the starch(B.leaf 1.5 %?7 %,B.stem 0.19 %?1.80 %)and soluble sugar(B.leaf 1.5 %?6 %,B.stem 0.03 %?3.46 %).In addition,the macronutrients(protein,carbohydrate and crude fat)content of B.bamboo was generally similar at feeding plots in winter,and only a few feeding plots showed some differences.The total nutrient content of Bashania fargesii in Paifanggou and Wafanggou areas was higher.4.On a fine scale,pandas do face differences in the ratio of protein and non-protein substances(P: NP)in their food.Due to the heterogeneity of the environment,pandas in winter habitats may face different nutritional intake status,but on the whole,the differences within the same region are not significant.