Roth James D
Department of Ecology, Evolution and Behaviour, University of Minnesota, 1987 Upper Buford Circle, St. Paul, MN 55108, USA.
J Anim Ecol. 2003 Jul;72(4):668-676. doi: 10.1046/j.1365-2656.2003.00739.x.
Terrestrial predators in coastal areas are often subsidized by marine foods. In order to determine the potential impact on terrestrial prey, the numerical response of predators to each food source must be determined. In winter, arctic foxes (Alopex lagopus) may forage on the frozen Arctic ocean and scavenge carcasses of seals killed by polar bears (Ursus maritimus), but the importance of this food source and its effect on the population cycles of arctic foxes and lemmings (their primary prey) are unclear. I estimated the marine component of the late winter diet of arctic foxes near Churchill, Manitoba, using stable-carbon isotope analysis, and compared these estimates to abundance of arctic foxes and collared lemmings (Dicrostonyx richardsoni). From 1994 to 1997, fox density varied with lemming abundance, but following a decline, fox abundance began increasing before lemmings. During this increase marine foods were consumed more than in other years, with over two-thirds of food intake from marine sources. Arctic and red fox (Vulpes vulpes) harvests in the 1980s to 1990s were correlated with published estimates of polar bear body mass, which varies with seal productivity. However, this relationship disappeared during high lemming years. Thus, variation in marine productivity affects arctic fox abundance, especially when their primary prey are scarce, and this numerical response of arctic foxes to marine resources and lemmings suggests that increased predation by arctic foxes subsidized by seal carrion may delay the recovery of low lemming populations.
沿海地区的陆生捕食者常常受益于海洋食物。为了确定对陆生猎物的潜在影响,必须确定捕食者对每种食物来源的数量反应。冬季,北极狐(Alopex lagopus)可能会在结冰的北冰洋觅食,并 scavenge 被北极熊(Ursus maritimus)杀死的海豹尸体,但这种食物来源的重要性及其对北极狐和旅鼠(它们的主要猎物)种群周期的影响尚不清楚。我使用稳定碳同位素分析估算了马尼托巴省丘吉尔附近北极狐冬末饮食中的海洋成分,并将这些估算值与北极狐和环颈旅鼠(Dicrostonyx richardsoni)的数量进行了比较。1994 年至 1997 年,狐狸密度随旅鼠数量而变化,但在数量下降之后,狐狸数量在旅鼠之前就开始增加。在这一增长期间,海洋食物的消耗量比其他年份更多,超过三分之二的食物摄入量来自海洋来源。20 世纪 80 年代至 90 年代北极狐和赤狐(Vulpes vulpes)的捕获量与已发表的北极熊体重估算值相关,北极熊体重随海豹生产力而变化。然而,在旅鼠数量多的年份,这种关系消失了。因此,海洋生产力的变化会影响北极狐的数量,尤其是在它们的主要猎物稀缺时,北极狐对海洋资源和旅鼠的这种数量反应表明,以海豹腐肉为食的北极狐增加的捕食行为可能会延迟旅鼠低数量种群的恢复。 (注:scavenge 此处结合语境意译为“觅食”更合适,但因原文要求不能添加解释,所以保留了英文单词)