In East Africa, climate change is predicted to reduce vegetation quality, and pervasive human disturbance has already resulted in significant declines in biodiversity. We studied the combined effects of reduced forage quality and human disturbance on faecal glucocorticoid metabolite (FGM) concentrations. We predicted that decreasing nutritional quality and increasing human disturbance would have an additive positive effect on FGM levels in wild impala (Aepyceros melampus). Employing a space-for-time approach, we used normalized difference vegetation index (NDVI) as a measure of forage quality, combined with spatially explicit proxies of human disturbance across areas of different protection management strategies in the Serengeti ecosystem. We collected 639 faecal samples, spread over 4 years, including both wet and dry seasons. Impala FGM levels increased significantly with declining NDVI and, to a lesser extent, with increasing proxies for human disturbance. However, we found no interaction between the two, such that impala had elevated FGM levels with low NDVI and low FGM levels with high NDVI regardless of human disturbance levels. This implies that impala will have high FGM levels if forage quality is poor, even with significant protection and reduced human disturbance. Understanding how animals respond to and cope with changes in forage quality and human land use across different protected areas is important for conservationists and managers to better protect species at risk and predict population viability.

中文翻译：

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在塞伦盖蒂生态系统中，气候引起的植被变化的后果超过了人类对野生黑斑羚的干扰。

在东非，预计气候变化将降低植被质量，普遍的人为干扰已导致生物多样性显着下降。我们研究了降低草料质量和人为干扰对粪便糖皮质激素代谢物（FGM）浓度的综合影响。我们预测，降低营养质量和增加人为干扰将对野生黑斑羚（Aepyceros melampus）的FGM水平产生累加的积极影响。）。我们采用时空方法，使用归一化差异植被指数（NDVI）作为草料质量的量度，并结合塞伦盖蒂生态系统中不同保护管理策略区域的人为干扰的空间明确代理。我们收集了639个粪便样本，分布在4年内，包括湿季和干季。随着NDVI的下降，黑斑羚的FGM水平显着增加，而随着人为干扰的增加，其程度也较小。但是，我们发现两者之间没有相互作用，因此，无论人为干扰水平如何，黑斑羚的FGM水平在NDVI较低的情况下都较高，而FGM在NDVI较高的情况下却较低。这意味着如果草料质量差，即使有明显的保护措施并减少了人为干扰，黑斑羚的FGM含量也会很高。