Mori Tomoki, Miura Kensuke, Takeuchi Hiroyuki, Niizuma Yasuaki
Institute for Mountain Science, Shinshu University, Kamiina County, Nagano Prefecture, Japan.
Graduate School of Agriculture, Meijo University, Tenpaku-ku, Nagoya, Japan.
PLoS One. 2025 Aug 18;20(8):e0330171. doi: 10.1371/journal.pone.0330171. eCollection 2025.
Sympatric species, commonly evolve behavioural mechanisms allowing them to coexist, thereby reducing direct competition for resources. In Japan, since the 1970s, the endemic Japanese serow (Capricornis crispus) and the sika deer (Cervus nippon) have been primarily allopatric. However, due to the rapid expansion of the sika deer population on Japan's main island of Honshu, the habitats of these two species now overlap. The significant and increasing overlap raises concerns about the potential impacts between these two (now sympatric) ungulates, including changes in distribution, shifts in activity patterns, or displacement due to interspecific competition. In this study, we investigated temporal and spatial segregation between Japanese serow and sika deer, from 2015 to 2017, in Shirakawa Village, Gifu Prefecture, Japan, by means of camera traps. Although our study was limited by a small sample size, it revealed no clear temporal or spatial segregation between the species, suggesting that there is potential for coexistence in shared habitats without pronounced competitive conflict, perhaps due to an abundance of food relative to sika deer density. Nevertheless, during autumn, reduced activity overlap rates, when the relative abundance index (RAI) of sika deer increased, may indicate that Japanese serow have modified their behavior to minimize resource competition. Specifically, during summer, when the RAI of sika deer was low, Japanese serow exhibited cathemeral behavior, whereas in autumn Japanese serow became nocturnal as sika deer RAI values increased. This seasonal adjustment indicates a context-dependent behavioural response that may serve to reduce temporal overlap and mitigate competition. Given the increasing sika deer population, understanding this potential for intensified competition becomes crucial for effective wildlife management and conservation efforts, particularly in maintaining the ecological balance between these species and ensuring the long-term sustainability of their habitats.
同域物种通常会进化出行为机制，使它们能够共存，从而减少对资源的直接竞争。在日本，自20世纪70年代以来，本土日本鬣羚（Capricornis crispus）和梅花鹿（Cervus nippon）主要是异域分布的。然而，由于梅花鹿种群在日本本州岛的迅速扩张，这两个物种的栖息地现在出现了重叠。这种显著且不断增加的重叠引发了人们对这两种（现在同域分布的）有蹄类动物之间潜在影响的担忧，包括分布变化、活动模式改变或种间竞争导致的取代。在本研究中，我们于2015年至2017年期间，在日本岐阜县白川村，通过相机陷阱调查了日本鬣羚和梅花鹿之间的时间和空间隔离情况。尽管我们的研究受到样本量小的限制，但结果显示这两个物种之间没有明显的时间或空间隔离，这表明在共享栖息地中有可能共存，而不会出现明显的竞争冲突，这可能是由于相对于梅花鹿密度而言食物充足。然而，在秋季，当梅花鹿的相对丰度指数（RAI）增加时，活动重叠率降低，这可能表明日本鬣羚已经改变了它们的行为，以尽量减少资源竞争。具体而言，在夏季，当梅花鹿的RAI较低时，日本鬣羚表现出昼夜活动模式，而在秋季，随着梅花鹿RAI值的增加，日本鬣羚变为夜间活动。这种季节性调整表明了一种依赖环境的行为反应，可能有助于减少时间重叠并减轻竞争。鉴于梅花鹿种群不断增加，了解这种竞争加剧的可能性对于有效的野生动物管理和保护工作至关重要，特别是在维持这些物种之间的生态平衡以及确保其栖息地的长期可持续性方面。
