The effect of body size on co-occurrence patterns within an African carnivore guild

Intraguild interactions among mammalian carnivores are important in shaping carnivore guild composition. Competing species may inhabit different areas and/or being active during different times to reduce the risk of aggressive interactions, but the role of body size in intraguild interactions within carnivore guilds remains largely unknown. We determined spatial and temporal co-occurrence of small, medium-sized and large carnivores of the carnivore guild in central Tuli, Botswana: lion Panthera leo, leopard Panthera pardus, spotted hyena Crocuta crocuta, brown hyena Parahyaena brunnea, black-backed jackal Canis mesomelas, bat-eared fox Otocyon megalotis, African wildcat Felis sylvestris lybica, African civet Civettictis civetta, honey badger Mellivora capensis and small-spotted genet Genetta genetta. We used camera trap data over a 2-year period and quantified the degree of temporal and spatial overlap by comparing activity patterns and calculating Pianka's index respectively. Our results showed that temporal overlap in activity between all carnivore species was high, but complete overlap was possibly reduced by differences in peak activity periods. In addition, low to moderate levels of spatial overlap were found between the different carnivore species, supporting the idea that small carnivore species inhabit different areas than large species to reduce the risk of interference competition. Due to the possible strong competition amongst sympatric carnivores there is a need for more knowledge on co-existence patterns for successful management and conservation of carnivore species, for example when carnivore species are (re)introduced in an area.

同功能群食肉目哺乳动物的类群内相互作用，对食肉动物功能群（carnivore guild）的群落组成塑造具有关键意义。存在竞争关系的物种往往会通过占据不同栖息空间、或调整活动时段来降低攻击性互作的风险，但食肉动物功能群内体型大小在类群间互作中的作用，目前仍鲜有研究探明。
本研究以博茨瓦纳中央图利地区的食肉动物功能群为研究对象，明确了其中小型、中型与大型食肉动物的空间与时间共存格局，涵盖物种包括：狮子（Panthera leo）、花豹（Panthera pardus）、斑鬣狗（Crocuta crocuta）、棕鬣狗（Parahyaena brunnea）、黑背胡狼（Canis mesomelas）、蝠耳狐（Otocyon megalotis）、非洲野猫（Felis sylvestris lybica）、非洲灵猫（Civettictis civetta）、蜜獾（Mellivora capensis）以及小斑獛（Genetta genetta）。研究采用为期两年的红外相机陷阱（camera trap）监测数据，通过比较活动节律分别量化物种间的时间重叠程度，并通过计算皮安卡指数（Pianka's index）量化空间重叠程度。
研究结果显示，所有食肉动物物种间的活动时间重叠度整体较高，但由于各物种种群的峰值活动时段存在差异，完全重叠的情况可能有所降低。此外，不同食肉动物物种间的空间重叠度处于低至中等水平，这一结果支持了“小型食肉动物会通过占据与大型物种不同的栖息空间，以降低干扰竞争（interference competition）风险”的假说。
鉴于同域分布（sympatric）的食肉动物间可能存在强烈竞争，为实现食肉动物物种的有效管理与保护（例如在某一区域重新引入或引入食肉动物物种时），亟需进一步掌握其共存模式相关知识。