四川羚牛春季地形选择特征的初步研究

地形是动物栖息地中非常稳定的环境因素。了解有蹄类特殊时期对地形的偏好,既有助于揭示动物行为策略形成的机制,又有助于我们实施保护和管理。本文对羚牛(Budorcas taxicolor tibetana)春季地形选择特征进行了初步探讨,数据来自于4只佩戴GPS无线电颈圈的羚牛3月中旬至4月中旬的定位数据。通过对羚牛活动位点与可选择地形的7个地形因素(坡度、坡向、坡位、海拔、地形起伏度、距峭壁距离、距山脊距离)的比较分析,发现羚牛在春季对地形存在选择。通过因子分析发现,影响羚牛春季地形选择的因素可以分为地形复杂度因子(坡度、地形起伏度),反捕食因子(海拔、距峭壁距离)和坡位因子(坡位)三类因素。与可供选择地形相比,羚牛利用的地形更偏离峭壁或陡坡、坡度更缓、海拔更低、明显偏离山脊、地形起伏程度较低。羚牛显著倾向于选择平坡和中位坡,且主要选择阴坡和阳坡。雌雄个体在7个地形因素的偏好上存在显著的差异,但雌性在距离峭壁和距离山脊的距离以及坡位的选择上与可供选择地形均无显著的差异。

Preliminary Study on Sichuan Takin (Budorcas taxicolor tibetana) Terrain Characters Preference in Spring

Terrain characters are considerable stable components, forming the base of wildlife habitat. To understand terrain preference of ungulates will largely assist management and conservation. Takin (Budorcastaxicolor tibetana) is a large ungulate that inhabit mountains with a rough terrain surface and low elevationarea during spring in Tangjiahe nature reserve. We primarily explored the terrain preference of takin during spring using data from 4 GPS-collared adult takin in period of March to April in 2008 and based on seven topographic factors (i.e. slope, aspect, slope position, elevation, topography ruggedness, distance to cliff, and distance to ridge). We found three groups of terrain factors (topography ruggedness, anti-predation and slope position) influenced takin terrain selection using factor analysis (Table 1). By testing the terrain difference between the sites used and randomly generated points within takin home range during spring, we found takin preferred to the habitat with specified terrain attributes. Takin were found to prefer the habitat with gentle slope, lower elevation, lower terrain ruggedness apart from ridge and cliff. We also found takin to utilize habitat with flat and mid-slope position on sunny slope or shady slope (Fig. 2). Although female were significant different from male on the 7 terrain characteristics , showing a preference to more complex terrain characters, female shown no preference to cliff or slope position selection by comparing with available habitat within its home range. In this study, the significant divergence between sexes on terrain preference may be an indicator of habitat segregation existing within takin population. These results should be incorporated into takin population and habitat management although the sample size was limited due to human disturbance occurred within low elevation area during the study period.