Spring Foraging Sites of Three Pheasants at Nanhua Part in Ailaoshan National Nature Reserve
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Abstract
Researching the mechanisms between species with close relationships or similar trophic levels that allow them to coexist is a central issue of community ecology. The study results are helpful to identify resource use traits and niche differentiation of sympatric species and to the biodiversity conservation of a region. Syrmaticus humiae, Lophura nycthemera and Arborophila rufogularis are sympatric species at Nanhua part in the Ailaoshan National Nature Reserve. Their relationship is genetically closed and their trophic niche is similar. Comparing trophic niche breadth and overlapping index for 18 ecological factors of spring foraging site among the three pheasants, the results showed that S. humiae held the least eurytopic factors (value of trophic niche breadth bigger than 0.8) (one factor) and the most stenotopic factors (its value less than 0.8) (four factors) of the three pheasants. L. nycthemera held three eurytopic and two stenopic factors, while A. rufogularis showed the reverse of S. humiae with six eurytopic and no stenotopic factors respectively. There were five factors with a high degree overlap in the niche overlapping index between S. humiae and L. nycthemera, while there were only four factors between S. humiae and A. rufogularis and two between L. nycthemera and A. rufogularis. Of the overlapping factors, shrub coverage, leaf litter coverage and seed density were common with a high degree overlap in the niche overlapping index among the three pheasants. The results of a one-way ANOVA indicated that five factors (aspect, tall tree density, herb coverage, seed density and density of edaphic animal) were not significant, while distance to open fields, distance to road and shrub coverage were significant for the three pheasants. Other factors were significant between any two species. The results of a principal component analysis showed that the cumulative percentage is 85.6% in the first 7 principal components for S. humiae, is 86.0% in the first 6 principal components for L. nycthemera and is 79.0% in the first 5 principal components for A. rufogularis. Factors affecting the selection of foraging sites in the three pheasants concentrate in the first 3 principal components. The factors difference of foraging sites among the three pheasants showed a state of mosaic, which meant that there was a separation of niches among the three species. The factor combination of each species prior selection was different as well the importance of each factor was also different.
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