Disease, predation and demography: assessing the impacts of bovine tuberculosis on African buffalo by monitoring at individual and population levels

1. Understanding the effects of disease is critical to determining appropriate management responses, but estimating those effects in wildlife species is challenging. We used bovine tuberculosis (BTB) in the African buffalo Syncerus caffer population of Kruger National Park, South Africa, as a case study to highlight the issues associated with estimating chronic disease effects in a long-lived host. 2. We used known and radiocollared buffalo, aerial census data, and a natural gradient in pathogen prevalence to investigate if: (i) at the individual level, BTB infection reduces reproduction; (ii) BTB infection increases vulnerability to predation; and (iii) at the population level, increased BTB prevalence causes reduced population growth. 3. There was only a marginal reduction in calving success associated with BTB infection, as indexed by the probability of sighting a known adult female with or without a calf ( P = 0·065). 4. Since 1991, BTB prevalence increased from 27 to 45% in the sou...

1. 明确疾病的致病效应是制定合理管控应对策略的核心前提，但针对野生动物物种开展此类效应的定量评估往往极具挑战。本研究以南非克鲁格国家公园（Kruger National Park）内的非洲水牛（Syncerus caffer）种群所感染的牛结核病（bovine tuberculosis, BTB）为研究案例，旨在探讨在长寿宿主物种中评估慢性疾病影响时所面临的各类问题。
2. 研究依托已知标识个体、佩戴无线电追踪项圈的水牛监测数据、航空种群普查资料，以及病原体流行率的自然梯度变量，对以下三个研究问题展开探究：（i）个体层面上，牛结核病感染是否会降低繁殖产出；（ii）牛结核病感染是否会提升宿主被捕食的脆弱性；（iii）种群层面上，牛结核病流行率的升高是否会导致种群增长速率下降。
3. 以已知成年雌性水牛是否伴随幼崽的观测概率作为产犊成功率的衡量指标，结果显示牛结核病感染仅对产犊成功率存在边际性的负面影响（P = 0.065）。
4. 自1991年以来，该种群的牛结核病流行率已从27%升至45%，在……