鼬獾(Melogale moschata)在野生動物傳染性疾病監測上所能扮演之角色: 以都市保護區為例

Abstract

傳染病監測是野生動物管理上很重要的一部分。野生動物的時空活動模式為監測、評估傳染病動態提供關鍵資訊。若一個物種本身帶有眾多病原、具有廣泛空間分佈、且與其他物種在時間活動上高度重疊，便可能是疾病傳播的有效促進者。本研究以臺灣低海拔地區常見的本土食肉目動物鼬獾(Melogale moschata)做為研究對象，選擇處於大臺北都會區的陽明山國家公園做為樣地，評估鼬獾是否適合作為食肉目動物疾病監測的哨兵物種（sentinel species）。我根據自動照相機的資料，使用物種佔據模型（occupancy modeling）來估計鼬獾的佔用機率(ψ)和被偵測機率(p)，並檢測可能影響鼬獾佔用機率的環境共變量（森林覆蓋度、與最近建物距離、與最近道路距離、遊蕩犬活動量、遊蕩貓活動量）。我使用了2020 年至 2023 年的相機紀錄，在47個相機樣點中，檢測到5種食肉目動物與3581筆紀錄。鼬獾為最常被相機記錄到的食肉目物種，其佔用機率也相對較高（0.93, 95%CI = 0.86-1），且與任一環境共變量間沒有顯著關連。在活動時間上，我使用核密度估計(kernel density estimation)進行估算，鼬獾與兩種原生食肉目動物（白鼻心、麝香貓）的重疊度高，特別是在距離道路或建物較近的地點。為了確認鼬獾的寄生蟲感染狀況，從2022年3月至2023年3月期間，我活捉22隻鼬獾並收集其血液、糞便和外寄生蟲樣本。我在鼬獾樣本中檢測到 4 個腸胃道寄生蟲類群，包括3類線蟲（Capillaria spp, Ancylostoma spp, Strongylidae nematode）和1類絛蟲（Taeniid）；2類血液寄生蟲（焦蟲Babesia spp, Ehrlichiaspp）與2種外寄生蟲（卵形硬蜱Ixodes ovatus, 蟎）。腸胃道寄生蟲的盛行率為0.81（17/21），其他盛行率較高的寄生蟲包括硬蜱（0.5，11/22）與焦蟲（0.6，9/15）。雖然鼬獾的寄生蟲感染狀況與食肉目動物的物種數、活動量與各環境共變量都沒有顯著關係，但陽明山國家公園內的鼬獾具分佈廣泛且活動時間與各食肉目動物重疊高等特性，其所帶之各類寄生蟲很有可能傳染給共域之其他食肉目動物，適合做為此區野生動物傳染病監測之哨兵物種。The monitoring of infectious diseases is becoming an important component of wildlife management. Spatiotemporal activity patterns of wildlife provide key information for monitoring and evaluating the dynamics of infectious diseases. A species that carries many parasites and pathogens, has a wide spatial distribution, and high overlap in diel activity with conspecifics, is likely to become an effective facilitator of disease transmission. This study focused on the Chinese ferret badger (Melogale moschata), a common native carnivore at lowland region in Taiwan, and evaluated whether they are a suitable sentinel species for carnivore diseases monitoring using Yangmingshan National Park (YMSNP) in the Taipei metropolitan. We used occupancy modeling to estimate occupancy probability (ψ) and detection probability (p) of the ferret badgers based on camera trap data. I tested whether their occupancy was influenced by environmental covariates (forest cover, distance to nearest human settlements, distance to the nearest major road, dog activity index, cat activity index). I used the camera trap data from a previous survey (2020 to 2023), which included 3581 detections of 5 carnivores at 47 camera sites. The ferret badgers dominated the detection records and their occupancy probability (0.93, 95%CI = 0.86-1) was relatively high compared to the other carnivores. Furthermore, the occupancy probability of the ferret badgers was not associated with any of the environmental covariates. I used kernel density estimation to quantify activity overlap among the carnivores. The ferret badgers overlapped in diel activity with the other two native carnivores (masked palm civets, small Indian civets), especially at sites closer to the major roads or human settlements. To confirm the infection status of parasites and pathogens in the Chinese ferret badgers, I live-trapped 22 individuals from March 2022 to March 2023, and collected their blood, fecal and ectoparasite samples. I detected 4 gastrointestinal helminth taxa including 3 nematode (Capillaria spp, Ancylostoma spp, Strongylidae nematode) and 1 cestode (Taeniid); 2 taxa of blood parasites and pathogens (Babesia spp, Ehrlichia spp), and 2 taxa of ectoparasites (ticks Ixodes ovatus, mites). The prevalence of the helminths was 0.81 (17/21). Other parasites with high prevalence included ticks (0.5, 11/22) and Babesia spp (0.6, 9/15). Although the infection status of the ferret badgers was unrelated to carnivore richness, carnivore activity level, or any of the environmental covariates, this study demonstrated that the Chinese ferret badger is: 1) widely distributed in YMSNP across different environmental conditions; 2) highly overlapped in diel activity with other carnivore species; and 3) host to many parasites and pathogens, making it a suitable sentinel species for wildlife disease monitoring in YMSNP.