Comparing The Diet And Habitat Selection Of Sympatric Blue Sheep (Pseudois Nayaur) And Red Deer (Cervus Elaphus Alxaicus) In Helan Mountains, China

Blue sheep (Pseudois nayaur) is one of Qinghai-Tibet Plateau endemic ungulates belong to the sunfamily Caprinae gunus Pseudois (Artiodactyla, Bovidae). It was listed in the II grade nationally protected animals of China. Helan Mountain is an important distribution area of blue sheep; their populations increased steadily in the past 20 years, and becoming a dominant species here. The increase of blue sheep's population resulted in a decrease of population in other ungulates and grassland degradation. Ungulates sympatric in Helan Mountain are blue sheep, red deer (Cervus elaphus alxaicus), and moschus sifanicus(Moschus chrysogaster). The population of ungulates in this region is believed to be an isolated geographical population, because the Helan Mountain is surrounded by Yinchuan City, deserts and Yellow river, and the competition among sympatric ungulates affected their survive. In this study, we analyzed the differences of diet and habitat selection by blue sheep and red deer, and made a further study on the coexistence mechanisms of them.From 2006 to 2008, we collected and studied the vegetation species consumed by sympatric blue sheep(Pseudois nayaur) and red deer(Cervus elaphus alxaicus) and their fecal samples in the Helan Mountains. The annual food component and proportion of blue sheep and red deer were studied with the fecal micro histological analysis. The habitat selection of sympatric blue sheep and red deer, especially the difference of them were studied based on direct observation and examination of fresh sites used by blue sheep and red deer throughout the study area. A total number of 480 composite samples of fresh feces of blue sheep and red deer were collected from 15 valleys.804 sites composed of 518 feeding and 286 bedding used by blue sheep and 661 sites composed of 341 feeding and 320 bedding used by deer were measured in the study area,202 random sites for the sites used by blue sheep and 707 random sites for the sites used by red deer were also measured, and the main results are as follows:(1) The food composition and diet seasonal changes of blue sheep were studied, results showed that blue sheep(Pseudios nayaur) in Helan mountains consumed 54 plant species (genera) belonging to 25 families in the whole year. In the diet of composition, the main families blue sheep foraged were Gramineae, Rosaceae, Ulmaceae and Leguminosae, making up the main food in the whole year. And Stipa spp. Poa spp.and Ulmus glaucescens that had high RD in the diet composition were most common and dominated the diet of blue sheep. Plant species blue sheep foraged revealed seasonal difference.35 plant species (genera) were identified in the microhistological analyses in summer, more than those in other three seasons. Shannon-Wiener H'was the highest in the four seasons. Index of diet niche in winter was the highest, followed by that in summer. (2) The food composition and diet seasonal changes of red deer were also studied, and results showed plant species red deer(Cerus elaphus alxaicus) in Helan Mountains foraged were 58 species (genera) from 25 families. We sonsidered red deer as polyphagous herbivores. In the whole year, Salicaceae, Rosaceae, Salicaceae and Gramineae in the diet composition made up 83.53%, were main food. The average RD of Salicaceae in the diet was 33.44%, followed by Rosaceae (19.99%), Salicaceae (15.22%) and Gramineae (15.13%). The average Rd of Salix microtachya var. bordensis, Ulmus glaucescens, Populus davidiana and Stipa spp. were 19.92%,16.11%,13.80%and 8.55%separately, making up 58.38%of diet composition of red deer. The characteristic of different plant category red deer showed seasonal variance. The sequence of plant category was trees (RD; 55.51%), shrubs (RD; 22.47%), grminoids (RD; 17.32%) and forbs (RD; 4.71%). The highest proportion of tree during the microhistological analyses on red deer fecal was in summer, making up the 89.27%of the diet composition. Shrubs made up 44.70%of the diet composition in winter. RD of grminoids in autumn was 56.38%and forbs 8.0%, lowest. Results showed that plant species, Pielou index, and index of diet niche were different among the four seasons. Plant species red deer foraged were 44, followed by spring and autumn, winter (22). Shannon-Wiener index of winter was the highest than that in the other three seasons. Pielou index in winter also was the highest,1.198, followed by autumn, and index of summer was the lowest. B, index of diet niche, was 8.234 in winter and 4.097 in spring.(3) Blue sheep and red deer in Helan mountains were sympatric, but the diet composition of them were significantly different, especially the main food of the two ungulates. Even though the Ulmus glaucescens, Stipa spp. and Poa spp. made up high proportion all the year in the diet of blue sheep and red deer, the RD of them revealed significant seasonal difference. Blue sheep foraged much gramineae, ulmaceae, rosaceae and umbelliferae. But red deer used more Salicaceae, ulmaceae, rosaceae, gramineae and leguminosae. The two ungulates had difference when they foraged salicaceae and gramineae. Blue sheep ate less salicaceae (1.01%) and more gramineae (49.48%). While red deer foraged more salicaceae (36.24%) and less gramineae (13.49%). The proportion of different plant category was different. Blue sheep used high proportion of graminoid (49.48%), followed by tree and shrub. Red deer foraged more tree (60.43%), followed by shrub and graminoid. Forbs were the least. And much food were overlap between blue sheep and red deer. High overlap index emerged in winter and spring, and main food was not overlap significantly.(4) The feeding and bedding habitat used by blue sheep were measured with the methods of fresh trace observation, assisting by direct observation in 4 seasons, and the data were analyzed by Chi-Square test, Kolmogorov-Smirnov Test, Bonferroni, Kruskal-Wallis H Test and PCA. The result showed that blue sheep preferred to use montane savanna dominated by Ulmus glaucescens when they feeding and bedding, and showed no significant preference to slope and direction, but activity mostly centered in higher slope habitat. Blue sheep preferred to select habitat close to bare rock in summer, autumn and winter, but not in spring. Blue sheep preferred to use habitats dominated by Ulmus glaucescens and dense high shrub as feeding, mostly in distinctly broken slope, close to bare rocks. They used Ulmus glaucescens under 4 m more frequently in summer and autumn, but used mixed trees include Ulmus glaucescens and some conifer below 6 m more in winter and spring. There were distinct differences in the bedding habitat selection of blue sheep in different seasons, they preferred to use montane savanna in spring, summer and autumn, but moved to montane grassland due to heavy snow in higher regions. Their bedding habitat required fewer shrub and fewer trees below 4 m, far from the bedding place.(5) The habitat selected by red deer (Cervus elaphus alxaicus) was analyzed with the same methods as blue sheep habitat selection. The result showed that red deer preferred to use habitat in gently smooth undulating slopes at higher altitude of more than 2000 m, and they migrated as season changing. There were significant seasonal changes in red deer's habitat selection for feeding and bedding. Red deer preferred montane grassland distributed in lower altitude in spring and winter, but montane conifer forest at higher altitude in summer and autumn. They preferred habitat with high and dense shrub, far from bare rock and high coverage. The slope was an important restrict factor for red deer in Helan Mountain regions, they preferred to use habitats in gentle slope within 10°.But they showed non-selective to the factors of distance to water resource and human disturbance.(6) The difference in habitat selection of blue sheep and red deer in different seasons was analyzed with chi-square test, Mann-Whitey U test and stepwise discriminant analysis. The result of stepwise discriminant and canonical discriminant coefficients showed that 17 eco-factors in feeding and bedding habitats used by blue sheep and red deer were almost completely separated, indicating a significant difference in their habitat selections. The result of chi-square test described an extremely significant difference (P < 0.01) between blue sheep and red deer in the using of vegetation types, topography, dominant tree and slope aspect. Mann-Whitey U test showed that blue sheep and red deer used tree density, tree height, shrub density, shrub height, food abundance, slope, hiding cover, distance to human disturbance and the distance to bare rock differently at extremely significant level (P<0.01) or significant level (P<0.05) in feeding habitat; and used shrub density, food abundance, slope, hiding cover, distance to bare rock, altitude and distance to human disturbance differently at extremely significant level (P<0.01) or significant level (P<0.05) in bedding habitat. The results showed that there were significant differences in habitat selections between blue sheep and red deer among 4 seasons, especially when the food resources was deficient. The habitat segregation is one of their strategies to meet an equal sharing of resources, which was consistent with our prediction.(7) The competition-coexistence mechanisms of sympatric distributed blue sheep and red deer in Helan Mountains was discussed. The result showed competition between blue sheep and red deer sympatric distributed in Helan Mountains in the using of food and space resources. They got co-existence with followed means:①Blue sheep and red deer co-existed by means of resource niche differentiation, there were great separations in diet and foraging strategies, including food types, foraging time and foraging habitat selection.②Blue sheep and red deer adapted to the environment and reduced competition in using different habitat patterns, to achieve benign symbiotic relationship in the same area.