苏格兰拉姆岛上野化山羊种群的取食生态学

2000年6～11月对苏格兰拉姆岛上野化山羊(Capra hircus)种群的取食生态学进行了研究.研究表明:山羊的觅食回合长度变化范围从1min到460 min不等,平均觅食回合长度是103.1±15.0 (SD)min,雌性动物的觅食回合长度较雄性的长(P=0.077).野化山羊单位时间的取食频率平均为46.3±0.6 口/min,取食频率随性别(P=0.023)和月份(P<0.001)而显著变化.雄性山羊在繁殖交配之前(6～7月)和之后(10～11月)的取食频率比繁殖交配期中(9～10月)的快(P<0.008),但雌性动物并没有这样的变化(P=0.327).雄性动物在繁殖交配期中的取食时间显著减少.雌、雄两性动物在取食频次和取食时间方面的这些差异可能导致该山羊种群在食物摄入量上的性别差异:雌性山羊的食物摄入量相对比较稳定,而雄性山羊的摄入量则变动很大.估计的食物摄入量随月份而下降(尽管9月份以后有一微小幅度的上升),这意味着拉姆岛上的山羊种群在食物匮乏而天气寒冷潮湿的冬季可能面临着能量收支不平衡的威胁.

Foraging ecology of feral goats on the Isle of Rum, NW Scotland

We studied foraging ecology of feral goats(Capra hircus)on the Isle of Rum, Scotland, from June to November 2000. Grazing bout length varied greatly from 1 min to 460 min with mean duration being 103.1±15.0(SD) min. Adult males and females differed marginally significantly in feeding bout length with females having relatively longer feeding bouts (P=0.077). The average bite rate for feral goats was 46.3±0.6 bites/min with significant variations between sexes (P=0.023) and among months (P<0.001). Adult males had faster bite rates during pre- (June-July) and post-rutting (October-November) periods than during rutting period (August-September) (P<0.008), but the bite rate of adult females during pre-rutting period was not different from that during rutting period (P=0.327). Adult males also spent significantly less daytime feeding during rutting period. The differences in bite rates and feeding time between the two sexes might result in sexual differences in forage intake by feral goats: females had relatively stable intake,but males fluctuated greatly in their forage intake. The estimated forage intake decreased from June to November (although a slight increase from September to November), which means that feral goats on Rum may be in negative energy balance during autumn/winter period when the quality of forage is lower and the weather is beginning to deteriorate. There was no significant difference in step rate while feeding between sexes or among months.