Spotted hyaena (Crocuta crocuta) feeding ecology and selectivity of large herbivorous prey in the Namib Desert

We have investigated the relationship between spotted hyaenas in the south Namib Desert and large herbivorous prey, and have summarized an updated overview of predator-prey relationships in this resource-limited arid environment. Over the 52-month study, we recorded the densities (#/km-2, + SE) of the four local large herbivorous prey species: gemsbok (1.229, + 0.50), springbok (1.352, + 0.48), ostrich (0.648, + 0.23), and greater kudu (0.343, + 0.00). A faecal analysis was performed on 146 collected spotted hyaena scats, and prey items were identified and hairs cross-follicle analysed to the species level. Spotted hyaena diet at the study area remained opportunistic with 240 identified prey items representing eight differing prey species being recorded, ranging from ostrich eggs to large ungulates. The Ivlev's Electivity Index was used to determine which large herbivorous prey was most selected for. Although gemsbok had a higher representation of prey items in the sampled scats, all sampled large herbivorous prey species scored below 0, and are thus generally avoided in relation to their availability in the environment. If any prey preferences are expressed by spotted hyaena in the Namib, it can be presumed to be a non-sampled prey species. We therefore promote further detailed investigations into all other prey species present, and seasonal variations of prey densities and scat sampling, within the study environment.

我们针对纳米布沙漠南部的斑鬣狗（spotted hyaena）与大型植食性猎物之间的关联展开了研究，并对这一资源受限的干旱环境中的捕食者-猎物关系进行了系统性综述更新。本次研究周期为52个月，期间我们记录了当地4种大型植食性猎物的种群密度（单位：只/平方千米，±标准误（SE））：南非剑羚（gemsbok，1.229，±0.50）、跳羚（springbok，1.352，±0.48）、鸵鸟（ostrich，0.648，±0.23）以及大捻角羚（greater kudu，0.343，±0.00）。研究人员对采集到的146份斑鬣狗粪便样本开展了粪便食性分析，通过对猎物残体进行鉴定，并利用毛囊交叉分析法将猎物精确鉴定至物种水平。研究区域内的斑鬣狗仍以机会主义策略觅食，本次研究共鉴定出240份猎物残体，涵盖8个不同的猎物物种，猎物类型涵盖鸵鸟卵至大型有蹄类动物。本研究采用Ivlev选择性指数（Ivlev's Electivity Index），以明确斑鬣狗对何种大型植食性猎物具有最高的捕食偏好。尽管南非剑羚在粪便样本的猎物残体中占比更高，但所有被采样的大型植食性猎物物种的指数得分均低于0，这表明相较于环境中该类猎物的可获得性，斑鬣狗整体上会回避捕食这些物种。若纳米布沙漠的斑鬣狗确实存在特定的猎物偏好，则其偏好的猎物大概率为本次研究未采样的物种。因此，我们倡议在本研究区域内，针对其余所有现存猎物物种、猎物密度的季节变化以及粪便采样方案开展更为深入细致的后续研究。