Data from: Response of moose hunters to predation following wolf return in Sweden

Background: Predation and hunter harvest constitute the main mortality factors affecting the size and dynamics of many exploited populations. The re-colonization by wolves (Canis lupus) of the Scandinavian Peninsula may therefore substantially reduce hunter harvest of moose (Alces alces), the main prey of wolves. Methodology/Principal findings: We examined possible effects of wolf presence on hunter harvest in areas where we had data before and after wolf establishment (n = 25), and in additional areas that had been continuously exposed to wolf predation during at least ten years (n = 43). There was a general reduction in the total number of moose harvested (n = 31,827) during the ten year study period in all areas irrespective of presence of wolves or not. However, the reduction in hunter harvest was stronger within wolf territories compared to control areas without wolves. The reduction in harvest was larger in small (500-800 km2) compared to large (1,200-1,800 km2) wolf territories. In areas with newly established wolf territories moose management appeared to be adaptive with regard to both managers (hunting quotas) and to hunters (actual harvest). In these areas an instant reduction in moose harvest over-compensated the estimated number of moose killed annually by wolves and the composition of the hunted animals changed towards a lower proportion of adult females. Conclusions/Significance: We show that the re-colonization of wolves may result in an almost instant functional response by another large predator—humans—that reduced the potential for a direct numerical effect on the density of wolves' main prey, the moose. Because most of the worlds' habitat that will be available for future colonization by large predators are likely to be strongly influenced by humans, human behavioural responses may constitute a key trait that govern the impact of large predators on their prey.

背景：捕食作用与人类狩猎收获是影响多数被开发利用种群的种群规模与动态的主要死亡因素。因此，灰狼（Canis lupus）重新定居斯堪的纳维亚半岛，或可大幅降低作为其主要猎物的驼鹿（Alces alces）的猎获量。

方法论/主要发现：本研究针对两类区域分析了狼的存在对猎获量的潜在影响：一类是在狼定居前后均有相关数据的区域（共25个），另一类是至少连续十年持续受狼捕食影响的区域（共43个）。在为期十年的研究周期内，所有区域的总猎获驼鹿数量（共计31827头）均出现普遍下降，且与狼是否存在无关。然而，与无狼的对照区域相比，狼领地内的猎获量下降幅度更大。相较于大型狼领地（1200-1800平方千米），小型狼领地（500-800平方千米）的猎获量下降幅度更为显著。在新建立狼领地的区域，驼鹿管理策略似乎对管理者（狩猎配额制定）与狩猎者（实际收获行为）均呈现出适应性调整。在这类区域，驼鹿猎获量的即时下降幅度超过了狼群每年预估捕杀的驼鹿数量，且猎捕动物的种群结构发生变化——成年雌性个体的占比有所降低。

结论与意义：本研究表明，灰狼的重新定居或可引发另一顶级捕食者——人类——的近乎即时的功能响应，这一响应削弱了狼群对其主要猎物驼鹿种群密度产生直接数量效应的可能性。由于未来可供大型捕食者定居的绝大多数全球栖息地均会受到人类的强烈影响，人类的行为响应或成为决定大型捕食者对其猎物产生影响程度的关键因素。