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 ( individuals consumed/year), the ring-tailed vontsira (Galidia elegans) ( consumed/year), and the fosa (Cryptoprocta ferox) ( 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）涵盖生境退化、外来物种入侵与狩猎活动，其对本土野生动物造成的广泛累积性负面影响，已在全球各类生境中得到充分证实。食肉动物因自身更易灭绝的生物学特征，可能是受此影响最脆弱的类群。
探究人为压力对同域分布食肉动物的影响，有助于提升我们制定针对性、高效管理方案的能力，以在全球范围内推进食肉动物保护工作。
本研究采用摄影调查、样线调查与生境采样手段，结合景观分析与基于村落的丛林肉狩猎访谈，首次针对马达加斯加最大的保护地——马索阿拉-马基拉（Masoala-Makira）景观，探究了多重生境退化形式（生境破碎化、外来食肉动物、人类入侵与狩猎活动）对食肉动物生境占用率（occupancy）的影响。
研究发现，随着生境退化程度加剧，本土食肉动物的生境占用率与遇见率呈下降趋势，而外来食肉动物的生境占用率与遇见率则显著上升。在该马达加斯加最大保护景观中，家猫（Felis属）与家犬（Canis familiaris）的生境占用率高于半数本土食肉动物类群。
鸟类与小型哺乳类的遇见率与外来食肉动物的生境占用率呈负相关，却与四种本土食肉动物的生境占用率呈正相关。斑尾马岛灵猫（Fossa fossana，spotted fanaloka）的生境占用率受到外来家猫与外来小灵猫（Viverricula indica，small Indian civet）存在的制约。
狩猎活动在本次研究的四个样地中均呈现高强度态势，年消费量最高的物种依次为小灵猫、环尾獴（Galidia elegans）与马岛獴（Cryptoprocta ferox，即fosa），原文未明确标注具体年消费个体数。
建模结果显示，狩猎者会优先选择食肉动物生境占用率、种群密度与物种丰富度均最高的完整森林区域开展狩猎活动。
上述各类人为压力及其对食肉动物种群的影响，尤其是外来食肉动物种群扩张与过度狩猎问题，具有广泛的全球影响，亟需制定有效管理方案，以应对影响马达加斯加乃至全球食肉动物种群的外来食肉动物入侵与不可持续狩猎问题。