Differences in spatial niche of terrestrial mammals when facing extreme snowfall: the case in east Asian forests

Tracks of seven mammal species (wild boar [Sus scrofa], Japanese serow [Capricornis crispus]), red fox [Vulpes vulpes], raccoon dog [Nyctereutes procyonoides], Japanese marten [Martes melampus]), Japanese hare [Lepus brachyurus]), Japanese macaque [Macaca fuscata]) left on the snow surface in eastern Japan from 2015 to 2020.Methods:We set 55 survey transects in low-mountain forests with mosaic landscapes below 800 m above sea level within the Towada, Asahi, and Oguni regions, located in northern Japan. In most areas in these regions, maximum snowfall with > 2 m in depth was normally observed. The total length of the transects was 21 km in Towada, 180 km in Asahi, and 111 km in Oguni. We followed the transects on skis during the daytime when snowfall, which obliterated mammal tracks from the snow surface, had not been observed for > 24 hours before each survey. Then, we recorded a geolocation of distinct tracks only when those intersected transects. We conducted this survey once a mid-winter from 2016 to 2020 in Towada, from 2014 to 2019 in Asahi, and from 2015 to 2019 in Oguni. Although we could not follow all the transects every year because of limitations due to weather conditions, the total length of the transects that we explored reached 1,144 km. The mean completion percentage of transects surveyed each year was 90% in Towada, 52% in Asahi, and 87% in Oguni.

本数据集记录了2015年至2020年日本东部区域积雪表面留存的7种哺乳动物足迹，涵盖物种包括野猪（Sus scrofa）、日本鬣羚（Capricornis crispus）、赤狐（Vulpes vulpes）、貉（Nyctereutes procyonoides）、日本貂（Martes melampus）、日本兔（Lepus brachyurus）以及日本猕猴（Macaca fuscata）。调查方法：我们于日本北部的十和田、朝日及小国区域内，选取海拔800米以下、具有镶嵌型景观的低山森林，布设了55条调查样线（survey transects）。上述区域多数区域的最大积雪深度通常可达2米以上。三条区域的样线总长度分别为：十和田21 km、朝日180 km、小国111 km。每次调查均于日间开展，我们身着滑雪装备沿样线行进，且需确保调查前24小时内未出现降雪——降雪会覆盖并清除积雪表面的哺乳动物足迹。仅当清晰可辨的哺乳动物足迹与样线相交时，我们才会记录其地理坐标（geolocation）。我们分别于2016至2020年、2014至2019年、2015至2019年的隆冬时节，在十和田、朝日、小国依次开展每年一次的调查。尽管受天气条件限制，我们无法每年完成全部样线的探查，但实际完成探查的样线总长度达1,144 km。各区域每年完成的样线调查占比均值分别为：十和田90%、朝日52%、小国87%。