冠羽畫眉(Yuhina brunneiceps)族群密度之空間結構及其與環境之關係

Abstract

Yuhina brunneiceps, an endemic Taiwanese bird species, is commonly found in regions of mid to high elevations. In order to better understand the spatial and environmental characteristics of its inhabitation, spatially distinctive populations were surveyed and examined from 141 sites in northern Taiwan. We analyzed the spatial correlation and structure of Yuhina brunneiceps population densities, and identified specific environmental variables important and attributable to the population. Yuhina brunneiceps populations were shown to have a clumped distribution. Moreover, a spatial correlogram revealed that the closer sites were to one another, the higher were the similarities of the densities themselves. A gradient profile was implied by this spatial structure. Of the environmental variables measured, the maximum elevation within 1×1-km grid, the total precipitation from November to March, the human population density, and a naturalness index were most important and commonly shared in the spatial structure. Interestingly, the latter 2 variables that are representative of human disturbance appeared to have stronger relations with the magnitude of the density than the other 2. By contrast, biological processes might be less influential in this aspect.