Johnson-Bice Sean M, Gable Thomas D, Homkes Austin T, Windels Steve K, Bump Joseph K, Bruggink John G
Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba, Canada.
Department of Fisheries, Wildlife and Conservation Biology, University of Minnesota, St. Paul, Minnesota, USA.
Ecol Appl. 2023 Oct;33(7):e2911. doi: 10.1002/eap.2911. Epub 2023 Sep 13.
Humans are increasingly recognized as important players in predator-prey dynamics by modifying landscapes. This trend has been well-documented for large mammal communities in North American boreal forests: logging creates early seral forests that benefit ungulates such as white-tailed deer (Odocoileus virginianus), while the combination of infrastructure development and resource extraction practices generate linear features that allow predators such as wolves (Canis lupus) to travel and forage more efficiently throughout the landscape. Disturbances from recreational activities and residential development are other major sources of human activity in boreal ecosystems that may further alter wolf-ungulate dynamics. Here, we evaluate the influence that several major types of anthropogenic landscape modifications (timber harvest, linear features, and residential infrastructure) have on where and how wolves hunt ungulate neonates in a southern boreal forest ecosystem in Minnesota, USA. We demonstrate that each major anthropogenic disturbance significantly influences wolf predation of white-tailed deer fawns (n = 427 kill sites). In contrast with the "human shield hypothesis" that posits prey use human-modified areas as refuge, wolves killed fawns closer to residential buildings than expected based on spatial availability. Fawns were also killed within recently-logged areas more than expected. Concealment cover was higher at kill sites than random sites, suggesting wolves use senses other than vision, probably olfaction, to detect hidden fawns. Wolves showed strong selection for hunting along linear features, and kill sites were also closer to linear features than expected. We hypothesize that linear features facilitated wolf predation on fawns by allowing wolves to travel efficiently among high-quality prey patches (recently logged areas, near buildings), and also increase encounter rates with olfactory cues that allow them to detect hidden fawns. These findings provide novel insight into the strategies predators use to hunt ungulate neonates and the many ways human activity alters wolf-ungulate neonate predator-prey dynamics, which have remained elusive due to the challenges of locating sites where predators kill small prey. Our research has important management and conservation implications for wolf-ungulate systems subjected to anthropogenic pressures, particularly as the range of overlap between wolves and deer expands and appears to be altering food web dynamics in boreal ecosystems.
人类通过改变景观,在捕食者 - 猎物动态关系中日益被视为重要参与者。这种趋势在北美北方森林的大型哺乳动物群落中已有充分记录:伐木形成的早期演替森林有利于有蹄类动物,如白尾鹿(Odocoileus virginianus),而基础设施建设和资源开采活动相结合产生的线性特征,使狼(Canis lupus)等捕食者能够在整个景观中更高效地移动和觅食。娱乐活动和住宅开发带来的干扰是北方生态系统中人类活动的其他主要来源,可能会进一步改变狼与有蹄类动物的动态关系。在此,我们评估了几种主要类型的人为景观改变(木材采伐、线性特征和住宅基础设施)对美国明尼苏达州南部北方森林生态系统中狼捕食有蹄类动物幼崽的地点和方式的影响。我们证明,每一种主要的人为干扰都显著影响狼对白尾鹿幼崽的捕食(n = 427个捕杀地点)。与“人类盾牌假说”(该假说认为猎物利用人类改造的区域作为避难所)相反,狼在比基于空间可得性预期更近的住宅建筑附近捕杀幼崽。幼崽在最近采伐的区域内被杀死的情况也比预期的多。捕杀地点的隐蔽覆盖度高于随机地点,这表明狼利用视觉以外的感官,可能是嗅觉,来探测隐藏的幼崽。狼对沿线性特征进行捕猎表现出强烈的偏好,而且捕杀地点也比预期更靠近线性特征。我们推测,线性特征通过使狼能够在高质量猎物斑块(最近采伐的区域、靠近建筑物的地方)之间高效移动,促进了狼对幼崽的捕食,同时也提高了与嗅觉线索的相遇率,使它们能够探测到隐藏的幼崽。这些发现为捕食者捕食有蹄类动物幼崽所采用的策略以及人类活动改变狼与有蹄类动物幼崽捕食者 - 猎物动态关系的多种方式提供了新的见解,由于定位捕食者捕杀小型猎物地点存在挑战,这些动态关系一直难以捉摸。我们的研究对受到人为压力的狼与有蹄类动物系统具有重要的管理和保护意义,特别是随着狼和鹿的重叠范围扩大,似乎正在改变北方生态系统中的食物网动态。