Managing the Impact of Recovering Mobile Predators on Endangered Birds Through Prey Switching: A Field Experiment in a Habitat Restoration Landscape i

在苏格兰的大片地区正在实施生态系统的恢复，其目标是恢复失去的生物多样性和生态系统功能。Cairngorms Connect伙伴关系旨在恢复自然栖息地，包括近600平方公里的喀里多尼亚松林。在这个区域内，数量过多的马鹿的密度正在通过扑杀而减少，栖息地正在恢复，捕食者的迫害没有发生，对捕食者的控制也非常有限。因此，迄今为止受到迫害的食肉动物数量正在恢复。虽然在一些峡谷中树木的再生是惊人的，但我们缺乏预测恢复将如何改变生态系统过程的能力。具体来说，有很多不确定因素，比如像长尾松鸡和黑松鸡这样的标志性本地物种，它们已经在减少，是重要的保护工作的重点，在有更充分的本地捕食者的景观中，它们将如何生存。这是一个需要证据的保护困境。减少鹿的放牧压力的必然结果是，大量的鹿肉（被淘汰的鹿的内脏）被丢弃在射击地点，因此几乎全年都可以作为人工引入脊椎动物捕食者的食物。我们假设这种外部资源的输入允许捕食者缓冲田鼠密度的变化，并保持比在未管理的生态系统中更高的密度。这种保护困境是由一群具有不同流动性的脊椎动物通才捕食者的功能、总体和数值反应所支撑的，这些捕食者能够以不同程度的盈利能力利用不同的猎物。其中一些猎物经历了多年周期（田鼠和红松鸡），它们的分布从源头到谷底都有明显的梯度。在这个项目中，我们将评估一个管理干预，包括1。当资源决定领土大小时，在关键地区清除石窟以减少捕食者密度。在为期八周的筑巢和育雏季节，在有规律间隔的食物堆内放置尸体和石锅，以转移捕食濒危地面筑巢鸟类的捕食者的注意力；这一应用的前提是，长尾松鸡和黑松鸡的蛋和雏鸡由于生命短暂，对捕食者来说是微不足道的营养资源，因此它们经历溢出捕食的频率反映了其他更重要猎物的丰度变化。我们的目标是确定在何处与猎物物种的空间分布有关，以及何时与其他猎物物种丰度的多周期有关，操纵捕食者食物消退是最有效的。这需要对捕食者群落对资源可用性的景观水平变化的功能和数值响应进行实证和建模研究。通过各种实地调查和基因捕获-再捕获调查来测量Capercaillie和/或黑松鸡种群参数，并根据结构化采样设计从粪便和羽毛中提取DNA，并使用空间捕获-再捕获模型进行分析。捕食者和猎物的密度将使用标准的野外方法和跟踪摄像机进行估计。这项研究很重要，因为它试图评估一种管理选择，使栖息地恢复与优先物种保护之间的协调成为可能，并揭示了在异质景观中，流动捕食者如何利用周期性/瞬态动态的替代猎物。它之所以有影响力，是因为它试图通过苏格兰标志性生态系统中的多机构合作伙伴关系，在积极修复的景观中实现这一目标。

The restoration of ecosystems is being implemented in large areas in Scotland with the goal of reinstating lost biodiversity and ecosystem functions. The Cairngorms Connect partnership aims to restore natural habitats including Caledonian pine forests over nearly 600km2. Within this area, the density of over-abundant red deer is being reduced through culling, habitat is recovering, persecution of predators does not occur, and predator control is extremely limited. As a result, populations of hitherto persecuted predators are recovering.While tree regeneration is spectacular in some glens, we lack any ability to predict how restoration will alter ecosystem processes. Specifically, there is much uncertainty about how iconic native species such as capercaillie and black grouse, which have been in decline and are the focus of significant conservation efforts, will fare in landscapes with a fuller complement of native predators. This is a conservation dilemma requiring evidence.A corollary of the drive to reduce deer grazing pressure is that a substantial amount of deer grallochs (the viscera of culled deer) is discarded at the shooting locations and thus available as artificially introduced food to vertebrate predators, almost year round. We hypothesise this external input of resources allows predators to buffer variation in field vole density and maintain higher densities than in an unmanaged ecosystem.The conservation dilemma is underpinned by the functional, aggregative and numerical responses of a guild of varyingly mobile, vertebrate generalist predators able to exploit different prey with varying degrees of profitability. Some of these prey experience multi-annual cycles (field voles and red grouse) and their distributions each follow distinct gradients from headwaters to valley floors.In this project, we will evaluate a management intervention that involves1. Removing grallochs to reduce predator density in key areas when resources dictate territory size.2. Provisioning of carcasses and grallochs at regularly-spaced food dumps during the eight-week nesting and brood-rearing season to act as diversionary feeding for predators exploiting the area occupied by endangered ground-nesting birds;The premise of this application is that the eggs and chicks of capercaillie and black grouse, by virtue of being ephemeral, are trophically trivial resources to predators, such that the frequency of spillover predation they experience reflects variation in abundance of other more important prey.Our objective is to establish where in relation to the spatial distribution of prey species, and when in relation to the multi-cycles of abundance of other prey species, it is most efficient to manipulate predator food subsides. This requires empirical and modelling studies of the functional and numerical response of the predator community to landscape level changes in resource availability.Capercaillie and/or black grouse population parameters, the main response variables, will be measured using various field surveys and genetic capture-recapture surveys, with DNA extracted from faeces and feather collected according to a structured sampling design, and analysed using spatial capture-recapture models. Predator and prey density will be estimated using standard field methods and trail cameras.The research is important because it seeks to evaluate a management option that would make it possible to reconcile habitat restoration with priority species conservation and sheds light on how mobile predators exploit alternative prey with cyclical/transient dynamics in heterogeneous landscapes. It is impactful because it seeks to achieve this in a landscape under active restoration by a multi-institutional partnership in an iconic ecosystem of Scotland.