Foraging Strategy,Habitat Selection And Assessment Of Tibetan Shou(Cervus Wallichii)in Green Grass Period Under The Influence Of Interspecific Competition

The Tibetan Shou(Cervus wallichii)is a species endemic to China and once considered extinct in the wild and now is only found in Sangri county,Shannan region,Tibet autonomous region with a population of 214-221.As there are several other wild ungulates and domestic animals with similar feeding habits within its habitat range,systematically exploring interspecies competition and co-existence between Tibetan Shou and other cohabiting ungulates in the highly unique environment of the Qinghai-Tibetan plateau,studying the foraging strategy and habitat selection of Tibetan Shou under the influence of interference competition,providing scientific evidence of conservation and management strategy of Tibetan Shou is of great significance for population recovery and development of Tibetan Shou.Through the distribution and fecal samples collection of Tibetan Shou and sympatric ungulates:white-lipped deer(Cervus albirostris),Tibetan gazelle(Procapra picticaudata),yak(Bos mutus),goat(Capra hircas),diet compositon,slection and overlap of Tibetan Shou and sympatric ungulates were analyzed;nutrient strategies,habitat selection strategies and habitat suitability evaluation of Tibetan Shou were discussed.At present,there're few studies on Tibetan Shou.From August to September from 2013 to 2016,24 transect lines(5km in length)were laid out in the Tibetan Shou nature reserve in Sanri according to the population distribution of Tibetan Shou and sympatric ungulates.A 10m×10m large quadrate was laid at the emergence point of the species,and a 2m×2m small quadrate was laid at the center and four corners of the quadrate.A total of 283 spots of Tibetan Shou,236 spots of white-lipped deer and 209 spots of Tibetan gazelle were collected,126 fecal samples of Tibetan Shou,106 fecal samples of white-lipped deer,98 fecal samples of Tibetan gazelle,98 fecal samples of yak and 72 fecal samples of goat were collected.Diet composition of Tibetan Shou and sympatric ungulates were analyzed by fecal microanalysis and trophic component of edible plants were measured in order to analyze the diet selection and overlap of Tibetan and sympatric ungulates and explore the foraging strategy of Tibetan Shou;The optimized muti-scale habitat selection model was used to analyze the overlap and separation of the habitat selection of Tibetan Shou and sympatric ungulates,the optimized setting Maxent model was used to evaluate the habitat suitability of Tibetan Shou.The ecological effects and adaptive mechanism of Tibetan Shou were discussed based on the overlap and separation of foraging and habitat selection between Tibetan Shou and sympatric ungulates.The results showed:1.Diet composition of Tibetan Shou and other 4 sympatric ungulates were analyzed by fecal microanalysis.Tibetan Shou fed on edible plants of 20 families and 37 species,compositae(29.66%),leguminosae(21.38%),salicaceae(9.64%),sedge(8.88%),polygonaceae(8.08%),graminosae(7.07%)and rosaceae(6.86%)were main edible plants families,Astragalusstrictus(12.8%),Leontopodiumpusillum(11.2%),Heteropappus semiprostratus(9.12%)and Salix xizangensis(9.64%)were the main edible plants.The food diversity index(1.32),evenness index(0.37)and niche width index(15.79)for Tibetan Shou had also indicated relatively higher scores.Leontopodium pusillum was found as a common main edible plant consumed by both Tibetan Shou(11.2%)and yak(10.16%),Salix xizangensis was a common main edible plant for Tibetan Shou(9.64%)and White-lipped deer(11.38%);At the family level,leguminosae was the common main edible plant family for Tibetan Shou(21.38%)and Tibetan gazelle(42.35%),compositae was also a main edible plant family for Tibetan Shou(29.66%),but also considered a secondary edible plant for White-lipped deer(7.42%),Tibetan gazelle(11.59%),yak(17.14%)and goat(14.14%).Food overlap indices of Tibetan Shou was found higher than 0.5,with the highest being for yak(0.65);Tibetan Shou fed on similar edible plants to other species,but differed in proportion with regards to dietary composition,as the main plants consumed were mostly considered secondary by others.Diet selection between Tibetan Shou and Sympatric ungulates was differentiated and trophic niche was separated.At the family level,compositae(29.66%),leguminosae(21.38%),salicaceae(9.64%)that accounted for a relatively high proportion of edible plants families of Tibetan Shou in green grass period have relatively balanced nutrition.2.A response surface model for the content of edible plants components and nutrients(energy,protein,fat,neutral detergent fiber,tannin)was constructed to quantify the nutritional strategy of Tibetan Shou in green grass period.The results of model analysis showed that Tibetan Shou preferred edible plants with high energy,protein and fat content,and low fiber and tannin content.Except Astragalus strictus(18.69%)have the highest protein content in the main and secondary edible plants,Kobresia littledalei(67.39%)and Festuca ovina(67.38%)as the content of neutral detergent fiber in the secondary edible plants and Potentilla parvifolia(0.18%)as the content of tannins are significantly higher,other main and secondary edible plants have relatively higher energy,protein and fat content and lower neutral detergent fiber and tannins content.Tibetan Shou adopted balanced nutritional foraging strategy which has consistent with the historical research.Edible plant species also increased significantly,from 23 species in 11 families to 37 species in 20 families,and validated Heller's expansive foraging strategy.The proportion of legumes increased significantly(21.38%)and became the main edible plant of Tibetan Shou,while the proportion of sedge decreased(8.88%).Legumes which has higher protein content and lower fiber content than sedge plants was regarded as high quality food of Tibetan Shou.The interpretation rate of deviation in the multi-scale model of habitat selection of Tibetan Shou(0.73),white-tailed deer(0.64)and Tibetan gazelle(0.65)was higher than that of the single-scale model,the influence of over-fitting on sampling deviation was well reduced.3.Habitat selection and overlap of Tibetan Shou and whited-lipped deer,Tibetan gazelle by optimized multi-scale habitat selection model was analyzed in order to discuss the habitat selection strategies of Tibetan Shou.The results of model analysis showed:Grassland ratio(15.54),cultivated land ratio(7.75),shrub ratio(4.70),population density(3.31)were the main influencing factors and distance from the primary road(1.67),distance from the second road(1.67),altitude(0.32)were the secondary influencing factors of Tibetan Shou habitat selection.Food and grazing were the main factors affecting the habitat selection of Tibetan Shou and sympatric wild ungulates,but there were still significant differences.Tibetan Shou showed a high performance for grassland shrub and cultivated land,while white-lipped deer showed a low performance for cultivated land and Tibetan gazelle tended to avoid shrub and cultivated land.Tibetan Shou and Tibetan gazelle preferred habitat with low slope and close distance from concentrated areas,while white-lipped deer preferred habitat with high slope and far distance from concentrated areas.Although there were some habitat overlap between Tibetan Shou and sympatric wild ungulates in green grass period,the habitat selection of Tibetan Shou and sympatric wild ungulates has been separated in different scales.The habitat selection strategies of Tibetan Shou in green grass period is generally consistent with the historical research,but it is significantly correlated with the distance from concertrated grazing areas and overgrazing had a serious impact on the habitat selection of Tibetan Shou.The deviation interpretation rate of multi-scal habitat selection model in Tibetan Shou(0.73),white-lipped deer(0.64)and Tibetan gazelle(0.65)was higher than that in the single-scale model and the overfitting influence on sample deviation was reduced.4.Taking into account the sampling deviation,data independence and complexity of model,the optimized Maxent model was used to evaluate the distribution of suitable habitat of Tibetan Shou in green grass period.The results showed:the Avg.test.or10pct(0.125)and Avg.diff.AUC(0.023)of optimized Maxent model were all significantly lower than that of the default Maxent model(Avg.test.or10pct,0.325;Avg.diff.AUC,0.039);the Avg.train.Auc(0.894)and Avg.test.AUC(0.879)of optimized Maxent model were all in high value and the model prediction performance was good;among all the environmental variables,the contribution rate of grassland was 55.95%and the significance was the highest;the prediction value of the model precision was 0.71 which was a good evaluation standard.The suitable habitat area of Tibetan Shou in green grass period was 479.92km2,accounting for 23.91%of the study area,showed patchy distribution.