Hunting, Exotic Carnivores, and Habitat Loss: Anthropogenic Effects on a Native Carnivore Community, Madagascar

The wide-ranging, cumulative, negative effects of anthropogenic disturbance, including habitat degradation, exotic species, and hunting, on native wildlife has been well documented across a range of habitats worldwide with carnivores potentially being the most vulnerable due to their more extinction prone characteristics. Investigating the effects of anthropogenic pressures on sympatric carnivores is needed to improve our ability to develop targeted, effective management plans for carnivore conservation worldwide. Utilizing photographic, line-transect, and habitat sampling, as well as landscape analyses and village-based bushmeat hunting surveys, we provide the first investigation of how multiple forms of habitat degradation (fragmentation, exotic carnivores, human encroachment, and hunting) affect carnivore occupancy across Madagascar’s largest protected area: the Masoala-Makira landscape. We found that as degradation increased, native carnivore occupancy and encounter rates decreased while exotic carnivore occupancy and encounter rates increased. Feral cats (Felis species) and domestic dogs (Canis familiaris) had higher occupancy than half of the native carnivore species across Madagascar’s largest protected landscape. Bird and small mammal encounter rates were negatively associated with exotic carnivore occupancy, but positively associated with the occupancy of four native carnivore species. Spotted fanaloka (Fossa fossana) occupancy was constrained by the presence of exotic feral cats and exotic small Indian civet (Viverricula indica). Hunting was intense across the four study sites where hunting was studied, with the highest rates for the small Indian civet (x¯ = 90 individuals consumed/year), the ring-tailed vontsira (Galidia elegans) (x¯ = 58 consumed/year), and the fosa (Cryptoprocta ferox) (x¯ = 31 consumed/year). Our modeling results suggest hunters target intact forest where carnivore occupancy, abundance, and species richness, are highest. These various anthropogenic pressures and their effects on carnivore populations, especially increases in exotic carnivores and hunting, have wide-ranging, global implications and demand effective management plans to target the influx of exotic carnivores and unsustainable hunting that is affecting carnivore populations across Madagascar and worldwide.人为干扰（anthropogenic disturbance）所带来的广泛且累积的负面效应，涵盖生境退化（habitat degradation）、外来物种（exotic species）与狩猎（hunting）等类型，已在全球多种生境中被充分记录；食肉目动物（carnivores）因更易走向灭绝的生物学特征，可能是其中最脆弱的类群。为提升全球食肉目动物保护的靶向性高效管理方案制定能力，亟需开展人为压力对同域分布食肉目动物（sympatric carnivores）影响的相关研究。本研究采用摄影采样、样线调查与生境采样方法，结合景观分析与村级野味狩猎调查，首次探究了多种生境退化类型（生境破碎化、外来食肉动物、人类入侵与狩猎活动）对马达加斯加最大保护区——马索阿拉-马基拉景观内食肉目动物占用率（occupancy）的影响。研究结果显示，随着生境退化程度加剧，本土食肉目动物的占用率与遇见率（encounter rates）均呈下降趋势，而外来食肉动物的占用率与遇见率则显著上升。在马达加斯加这片最大的保护景观中，野猫（Felis species）与家犬（Canis familiaris）的占用率高于半数本土食肉目物种。鸟类与小型哺乳类的遇见率与外来食肉动物的占用率呈负相关，却与四种本土食肉目物种的占用率呈正相关。斑扇狐（Spotted fanaloka, Fossa fossana）的占用率会受到外来野猫与外来小灵猫（Viverricula indica）存在的制约。本次研究涉及的四个狩猎调查样地中，狩猎活动均十分频繁，其中受猎捕量最高的物种为小灵猫（年均猎捕量x̄=90只/年）、环尾獴（Galidia elegans，年均猎捕量x̄=58只/年）与马岛獴（Cryptoprocta ferox，年均猎捕量x̄=31只/年）。模型结果显示，狩猎者会选择食肉目动物占用率、种群多度（abundance）与物种丰富度（species richness）均最高的完整森林区域进行捕猎。上述各类人为压力及其对食肉目动物种群的影响，尤其是外来食肉动物数量上升与狩猎活动加剧，具有广泛的全球影响，亟需制定高效管理方案，以应对影响马达加斯加乃至全球食肉目动物种群的外来食肉动物入侵与不可持续狩猎问题。