In Japan, invasive raccoons cause severe ecological and social problems by transmitting pathogens to humans, livestock, and native species, causing substantial crop damage, and competing with native species. Possible competition between invasive raccoons and native raccoon dogs is of concern in Japan because Japanese raccoon dogs have a limited distribution and are native only to Japan and the two species have similar characteristics. We assessed potential competition between raccoons and raccoon dogs by comparing feeding habits and habitat use. Both species were captured in Hokkaido, Japan from 2004 to 2017. More raccoons were captured close to agricultural land at the forest periphery (70.1%, 358/511); conversely, more raccoon dogs were captured in the forest core (74.9%, 253/338). Feeding habits were then examined by fecal analysis and stable isotope analyses. Fecal analysis revealed both species to be opportunistic omnivores that consumed easily found food items. However, raccoon feces contained more crops, whereas raccoon dog feces contained more insects, reflecting the different locations in which the species were trapped. Moreover, stable isotope ratios were significantly higher in raccoons than raccoon dogs (Corn has the highest carbon stable isotope (δ13C) value, and amphibians and reptiles are high in nitrogen stable isotope (δ15N); forest resources such as insects and wild fruits are low in δ13C and δ15N). We conclude that both species ate similar food types, but their food preferences appeared to differ. Raccoon and raccoon dog habitat use also differed, possibly because the two species inhabited areas where they could easily obtain their preferred foods. Therefore, the current feeding habits and habitat use of raccoons do not appear to overlap sufficiently with those of raccoon dogs to impact the latter. The results of this study, particularly the stable isotope data, may provide a useful precedent for future studies of competition in medium-sized mammals, particularly canids.

中文翻译：

---

日本北海道侵入性浣熊与本地浣熊的摄食习性和栖息地使用情况的比较

在日本，入侵性浣熊通过将病原体传播给人类，牲畜和本地物种，造成严重的农作物损害并与本地物种竞争，从而引起严重的生态和社会问题。在日本，侵入性浣熊与本地浣熊之间的竞争可能引起关注，因为日本浣熊的分布有限，并且只在日本本土生，并且两个物种具有相似的特征。通过比较喂养习惯和栖息地使用情况，我们评估了浣熊和狗之间的潜在竞争。2004年至2017年在日本北海道捕获了这两种树种。在森林外围靠近农田的地方捕获了更多的浣熊（70.1％，358/511）；相反，在森林核心地区捕获了更多的狗（74.9％，253/338）。然后通过粪便分析和稳定的同位素分析检查喂养习惯。粪便分析表明，这两种都是机会杂食性食物，容易食用。但是，浣熊的粪便含有更多的农作物，而浣熊的狗粪含有更多的昆虫，这反映了该物种被困在不同的位置。此外，浣熊中的稳定同位素比率显着高于浣熊狗（玉米具有最高的碳稳定同位素（δ13C）值，两栖动物和爬行动物的氮稳定同位素（δ15N）高；森林资源（例如昆虫和野生水果）低（δ13C和δ15N）。我们得出的结论是，两种物种都食用相似的食物类型，但是它们的食物偏好似乎有所不同。浣熊和狗的栖息地使用方式也有所不同，可能是因为这两个物种居住在他们可以轻松获得自己喜欢的食物的地区。因此，目前浣熊的摄食习惯和栖息地使用情况似乎与浣熊犬的重叠程度不足以影响后者。这项研究的结果，特别是稳定的同位素数据，可能为将来对中型哺乳动物，尤其是犬科动物的竞争研究提供有用的先例。