Revealing the hidden effects of anthropogenic disturbance on the spatiotemporal dynamics of animal populations

在全球范围内，由于人类活动施加的压力越来越大，自然生态系统正受到威胁。许多生态系统正在变得支离破碎或在边缘受到侵蚀，而即使在保护区的核心也能感受到人类干扰的影响。通常，人类活动或人类改变环境的影响是显而易见的：当自然栖息地被破坏时，无法逃脱的动物将会灭绝；人类通过偷猎、狩猎或捕鱼直接收获野生动物；基础设施，如风力涡轮机或道路，会导致碰撞，导致动物死亡；而疾病可能会从牲畜传播，导致野生种群大量死亡。除了这些直接影响，许多研究表明，人类如何对动物产生更微妙的影响。例如，人类活动可以诱导回避行为，限制进入重要觅食区域，增加压力和警觉水平，并通过向环境中引入噪音和光线来干扰感觉机制。虽然不那么明显，但这些间接影响可能会产生巨大的影响，因为许多动物在其生理极限的边缘活动，从而使它们的能量需求与资源可获得性得到很好的平衡，虚弱的个体可能很快就会屈服于捕食者、寄生虫或疾病。这意味着，即使是人类活动的细微影响也会显著降低动物存活和繁殖的可能性，这反过来又会转化为种群数量的大幅突然下降。在这项研究中，我们将调查人类压力增加对角马迁徙种群的影响，角马是生活在东非大塞伦盖蒂生态系统的关键物种。我们将评估人类的干扰如何改变动物的移动方式，它们花费多少时间消耗资源而不是保持警惕，以及这些因素如何影响它们的身体状况。我们将测试这些影响是否会改变个体的存活概率和他们有存活后代的机会。为了评估人类干扰对运动和活动的影响，我们将使用安装在项圈上的GPS设备和活动传感器，我们将部署在迁徙角马上，结合对资源分布(植被和土壤养分地图)和风险(人类基础设施位置、旅游、非法狩猎活动和自然捕食)的全面描述。GPS项圈和传感器将允许我们跟踪动物，并确定它们对这些环境特征的反应，包括它们在太空中的活动方式，以及它们分配给不同活动的时间。为了评估身体状况如何影响生存和繁殖，我们将分析角马尾毛生长过程中沉积的代谢物。我们将首先校准我们对已知身体状况的动物的分析，然后使用这种方法来评估不同原因死亡的动物的身体状况。这将使我们能够估计糟糕的身体状况如何降低角马的生存概率。使用类似的分析，我们将确定动物是否繁殖，并使用实地调查来测量小牛存活率。为了了解人类的间接影响如何扩大到影响种群的弹性，我们将使用积分预测模型，这是一个框架，允许我们使用个体水平的数据来预测种群水平将发生的事情。通过将经验数据收集与将个体生死率与人口动态联系起来的数学模型相结合，我们可以问，如果人类活动在特定地区增加，或者如果气候变化导致不同的资源分布，人口丰度会发生什么。这项研究将是对人类对生态系统影响的最详细评估之一，并将为科学家和管理人员提供有关如何在未来保持生态系统弹性的重要信息。

Globally, natural ecosystems are under threat due to the ever increasing pressures imposed by human activities. Many ecosystems are becoming fragmented or are being eroded at the edges while the effects of human disturbance are being felt even at the core of protected areas. Often, the impact of human activity or human-altered environments is obvious: when natural habitats are destroyed animals that can't escape will perish; humans directly harvest wild animals through poaching, hunting or fishing; infrastructure, such as wind turbines or roads, lead to collisions that kill animals; while diseases can spread from livestock and decimate wild populations. Beyond these direct impacts, much research has shown how humans can have more subtle effects on animals. For example, human activities can induce avoidance behaviour and restrict access to vital foraging areas, increase stress and vigilance levels, and interfere with sensory mechanisms by introducing noise and light into environments. While not as obvious, these indirect effects can have large impacts since many animals operate at the edge of their physiological limits whereby their energetic demands are finely balanced with resource availability, and weakened individuals can quickly succumb to predators, parasites, or disease. This means that even subtle impacts of human activity can significantly reduce the probability that an animal will survive and reproduce, which in turn can translate to large and sudden declines in the population.In this research we will investigate the effects of increased human pressures on the migratory population of wildebeest, a keystone species that inhabit the Greater Serengeti ecosystem in East Africa. We will assess how human disturbance is changing how animals move, how much time they spend consuming resources as opposed to being vigilant, and how these factors are affecting their body condition. We will test if these effects alter the survival probability of individuals and the chance that they have viable offspring.To evaluate the effects of human disturbance on movement and activities, we will use GPS devices and activity sensors mounted on collars that we will deploy on migratory wildebeest, combined with a comprehensive description of the distribution of resources (vegetation and soil nutrient maps) and risks (location of human infrastructure, tourism, illegal hunting activities, and natural predation). The GPS collars and sensors will allow us to track animals and determine how they respond to these environmental features, both in terms of how they move around in space, and how much time they allocate to different activities. To assess how body condition affects survival and reproduction we will analyse metabolites that get deposited in wildebeest tail hair as it grows. We will firstly calibrate our analysis on animals of known body condition, and then use this method to assess the body condition of animals that have died of different causes. This will allow us to estimate how poor body condition reduces a wildebeest's probability of survival. Using a similar analysis we will determine whether animals have reproduced and use field surveys to measure calf survival rates.To understand how indirect effects of humans scale-up to impact the resilience of the population, we will use Integral Projection Models, a framework that will allow us to use data at the individual level to predict what will happen at the population level. By combining empirical data collection with mathematical models that link individual vital rates with population dynamics, we can ask what happens to the population abundance if human activities increase in specific areas, or if climate change leads to different distributions of resources. This research will be one of the most detailed assessments of the effects of humans on an ecosystem and will provide scientists and managers with vital information about how to keep ecosystems resilient in the future.