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首页> 外文期刊>Ecological research >Estimating seasonal density of blue sheep (Pseudois nayaur) in the Helan Mountain region using distance sampling methods
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Estimating seasonal density of blue sheep (Pseudois nayaur) in the Helan Mountain region using distance sampling methods

机译：利用距离采样法估算贺兰山地区蓝羊（Pseudois nayaur）的季节性密度

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The monitoring of animal populations is necessary to conserve and manage the rare or harvest species and to understand the population change over several years. We used distance sampling methods to estimate seasonal density of blue sheep in a 2,740 km~2 area of Helan Mountain region by walking along 32 transect lines from winter 2003 to autumn 2005. In all, 367-780 blue sheep were observed in 91-143 groups in the surveys during the seasons. Observed mean group size ranged from 3.42 to 8.35 individuals; encounter rate, the number of groups detected per kilometre, varied from 0.19 to 0.30 during the seasons. A hazard rate key function with cosine series expansion and a half-normal key function with either cosine or simple polynomial series expansion were the best fitting models based on the lowest value of Akaike's information criterion (AIC). Density estimates varied between 3.627 sheep per square kilometre in spring 2004 and 4.635 per square kilometre in summer 2005. There were no detectable differences in estimated density among seasons (P = 0.887). The estimated density of blue sheep was negatively correlated with the total number of deaths (P < 0.05), number of sub-adult males' deaths (P < 0.05), number of sub-adult females' deaths (P < 0.05), and number of male lambs' deaths (P < 0.05). We concluded that distance sampling surveys should be used to monitor long-term population trends to provide the best quantitative estimates of blue sheep populations in the Helan Mountains region.
机译：必须对动物种群进行监测，以保护和管理稀有或收获物种，并了解几年来种群的变化。从2003年冬季到2005年秋季，我们通过沿32条样带线步行，使用距离采样方法估算了贺兰山区2,740 km〜2区域内的蓝绵羊的季节性密度。在91-143个地区共观测到367-780只蓝绵羊在季节中进行调查的小组。观察到的平均组人数为3.42至8.35个人；遇到率，每公里检测到的组数在季节中从0.19到0.30不等。基于Akaike信息准则（AIC）的最小值，具有余弦级数展开的危险率键函数和具有余弦或简单多项式级数展开的半正态键函数是最佳拟合模型。密度估计值在2004年春季的每平方千米3.627只羊和2005年夏季的每平方千米4.635只之间变化。各季节之间的估计密度没有可检测到的差异（P = 0.887）。蓝羊的估计密度与死亡总数（P <0.05），亚成年男性死亡数（P <0.05），亚成年女性死亡数（P <0.05）和负相关。雄性羔羊死亡人数（P <0.05）。我们得出结论，应使用距离抽样调查来监测长期种群趋势，以提供贺兰山脉地区蓝羊种群的最佳定量估计。

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