Effects of land use on Eurasian otter presence in northeast China

Eurasian otters ( Lutra lutra ) occur across Asia, Europe, and northern Africa, yet many populations are declining or endangered. Otter populations in northeast China have decreased substantially over the past 70 years, which is generally attributed to land use change, though this hypothesis remains untested. We examined the relationship between land use and otter occurrence in Jilin Province by characterizing land use in 100-m river buffers extending 7.5 km up and downstream from each of 58 known otter occurrences compared to 100 randomly selected pseudo-absence points across the same landscape. Logistic regression revealed that otters were less likely to occur as agricultural land increased (p=0.00347). We also observed negative but nonsignificant trends between otter presence and average cropland patch size, percentage of built-up land, and average built-up patch size. A Principal Component Analysis explained 48.7% of total landscape variation and indicated that locations where otters were known to be present were less variable in landscape conditions (i.e., amount and size of agricultural and urbanized patches) compared to random locations. Overall, this ensemble approach suggests that otters are affected by land use at least at a localized scale, complementing other studies within its range.