Using Japanese badger home range size to estimate occupancy in Tokyo

Abstract

We evaluated the green areas in Tokyo as potential habitats for Japanese badgers (Meles anakuma) based on previously reported home range size. We identified green areas from a vegetation map (2000–2011) and used them as candidates for potential habitat availability. We then determined the proportion of these continuous green areas that exceeded the viable minimum home range size required by Japanese badgers. From previous studies, the minimum size required by females was 5.2 ha. We also used 30.0 ha according to a habitat suitability index. For males, the maximum size in suburban Tokyo’s Satoyama landscape is 72.1 ha, and up to 407.1 ha in the mountainous Nagano area. Our analysis showed that the mean size of Tokyo’s green areas decreased from west (natural/suburban habitat) to east (urban habitat); indeed, 88.9% of the entire green areas in Tokyo were in the western region. We found 17 continuous green areas covering 72.1 to 407.1 ha in the western and central region, i.e., the range likely to be large enough to support Japanese badgers, and only two green areas exceeded 407.1 ha. In the eastern region, there were only two green areas covering 72.1 to 407.1 ha, and no green areas ≥407.1 ha. Our study suggests that the reason why badgers are known to occur in western and central, but not eastern Tokyo, is likely due to a lack of available continuous habitat in this eastern region.