随着人为足迹的扩大,大型陆地哺乳动物越来越依赖人类改造的景观。土地管理活动,如木材采伐,农业,和道路可以通过改变栖息地来改变饲料资源和捕食风险,从而影响猎物种群动态,但是在捕食者行会多样化和不断变化的地区,这些影响还没有得到很好的理解。在华盛顿州东北部,美国,白尾鹿(Odocoileusvirginianus)容易受到多种食肉动物的伤害,包括最近返回的灰狼(Canis狼疮),在高度人为改造的景观中。为了理解人类环境中控制捕食者-食饵动态的因素,我们用无线电领280头白尾鹿,33只山猫(LynxRufus),50美洲狮(美洲狮concolor),28土狼(C.latrans),在2016年至2021年之间有14头狼。我们首先估计了鹿的生命速率,并使用了阶段结构化的矩阵模型来估计其人口增长率。在研究期间,我们观察到鹿种群稳定到下降(λ=0.97,95%置信区间:0.88,1.05),74%的蒙特卡罗模拟表明人口减少,26%的模拟表明人口增加。然后,我们拟合Cox比例风险模型来评估捕食者如何暴露,利用人类改造的景观,冬季的严重程度影响了鹿的生存,并利用这些关系来评估对总体人口增长的影响。我们发现,人口增长率受到顶端捕食者的负面直接影响以及木材采伐和农业面积的积极影响的双重影响。美洲狮对鹿种群动态的影响比狼更强,中捕食者对鹿种群增长率影响不大。最近的木材采伐地区的牧草生物量比老森林多55%,但是水平能见度没有差异,这表明木材采伐不会影响捕食风险。尽管靠近道路并不影响总体人口增长率,车辆碰撞导致了相当大比例的鹿死亡,减少这些碰撞对鹿和人类来说可能是双赢的。顶点捕食者和草料的影响表明,在这种高度人为修饰的系统中,自上而下和自下而上的因素存在双重限制,这表明,由于饲料供应有限,顶端捕食者的减少将加强对鹿种群的密度依赖性调节。
Large terrestrial mammals increasingly rely on human-modified landscapes as anthropogenic footprints expand. Land management activities such as timber harvest, agriculture, and roads can influence prey population dynamics by altering forage resources and predation risk via changes in habitat, but these effects are not well understood in regions with diverse and changing predator guilds. In northeastern Washington state, USA, white-tailed deer (Odocoileus virginianus) are vulnerable to multiple carnivores, including recently returned gray wolves (Canis lupus), within a highly human-modified landscape. To understand the factors governing predator-prey dynamics in a human context, we radio-collared 280 white-tailed deer, 33 bobcats (Lynx rufus), 50 cougars (Puma concolor), 28 coyotes (C. latrans), and 14 wolves between 2016 and 2021. We first estimated deer vital rates and used a stage-structured matrix model to estimate their population growth rate. During the study, we observed a stable to declining deer population (lambda = 0.97, 95% confidence interval: 0.88, 1.05), with 74% of Monte Carlo simulations indicating population decrease and 26% of simulations indicating population increase. We then fit Cox proportional hazard models to evaluate how predator exposure, use of human-modified landscapes, and winter severity influenced deer survival and used these relationships to evaluate impacts on overall population growth. We found that the population growth rate was dually influenced by a negative direct effect of apex predators and a positive effect of timber harvest and agricultural areas. Cougars had a stronger effect on deer population dynamics than wolves, and mesopredators had little influence on the deer population growth rate. Areas of recent timber harvest had 55% more forage biomass than older forests, but horizontal visibility did not differ, suggesting that timber harvest did not influence predation risk. Although proximity to roads did not affect the overall population growth rate, vehicle collisions caused a substantial proportion of deer mortalities, and reducing these collisions could be a win-win for deer and humans. The influence of apex predators and forage indicates a dual limitation by top-down and bottom-up factors in this highly human-modified system, suggesting that a reduction in apex predators would intensify density-dependent regulation of the deer population owing to limited forage availability.