ABSTRACT

Darwin’s fox is an opportunistic omnivorous predator native to Chile classified as endangered by the IUCN Red List. Habitat use by Darwin’s foxes can be negatively affected by the presence of free-ranging dogs that range freely across native and non-native habitats and can be a source of fox mortality. The objective of this study was to analyze the isotopic similarity of Darwin’s fox and sympatric free-ranging dogs in Chiloé Island to determine the impact of anthropogenic environmental alterations on wild predators. We use hair samples to characterise and compare their δ¹³C and δ¹⁵N values and to evaluate isotopic similarity and isotope niches overlap. A generalised linear model was used to associate the isotope value with landscape variables (forest cover and vegetation type) and distance to the nearest house. We found no significant differences in δ¹³C or δ¹⁵N values between foxes and dogs, and a marginally significant isotope niche overlap (59.4 %). None of the selected variables at landscape and site scale were related to isotope values. Although our study is not a probe of direct contact between foxes and free-ranging dogs, the high isotopic similarity highlights the risk of pathogen spillover from free-ranging dogs to Darwin’s foxes.

摘要

达尔文狐狸是一种机会主义的杂食性捕食者，原产于智利，被世界自然保护联盟红色名录列为濒危物种。达尔文狐狸的栖息地使用可能会受到自由放养的狗的负面影响，这些狗可以在本地和非本地栖息地自由活动，并且可能成为狐狸死亡的来源。本研究的目的是分析达尔文狐狸和奇洛埃岛同域自由放养犬的同位素相似性，以确定人为环境改变对野生捕食者的影响。我们使用头发样本来表征和比较它们的δ ¹³ C 和δ ¹⁵N 值并评估同位素相似性和同位素生态位重叠。使用广义线性模型将同位素值与景观变量（森林覆盖和植被类型）以及到最近房屋的距离相关联。我们发现狐狸和狗之间的δ ¹³ C 或δ ¹⁵ N 值没有显着差异，并且同位素生态位重叠略显重要 (59.4 %)。景观和场地规模的选定变量均与同位素值无关。虽然我们的研究不是探索狐狸和散养狗之间的直接接触，但高同位素相似性突出了病原体从散养狗溢出到达尔文狐狸的风险。