Multiphase processes of seed dispersals via masked palm civets as a non-native species in cool-temperate forests of northern Japan

Abstract

The disappearance of large seed dispersers such as primates increases the dependence of endozoochorous plants bearing large fruits on frugivorous mesocarnivores for seed dispersal. Ecosystems in northern Japan are typical examples wherein the distribution and abundance of large-sized dispersers (i.e., Macaca fuscata and Ursus thibetanus) have been constrained mainly owing to past anthropogenic disturbances. Moreover, the distribution of several native mesocarnivores has been fragmented, although masked palm civet, Paguma larvata, a non-native frugivorous mesocarnivore, has expanded its distribution over the past quarter-century. Here, we evaluated the roles of this non-native species in defaunated cool-temperate forests by assessing primary and secondary seed dispersal via civets. To assess the primary dispersal process, we identified their possible latrines, where seeds were initially dispersed, by tracking radio-tagged civets. We then compiled an inventory of seeds transported by civets combining the results of the fecal analysis performed in this study and a literature survey for seeds known to be transported by civets. To explore secondary seed dispersals, we first determined the ability of civet feces to attract dung beetles using pitfall traps and then compared this ability of civet feces with that of the feces of raccoon dog, Nyctereutes procyonoides, a native mesocarnivore. Our findings showed that (1) over 90% of the civet latrines confirmed within forested areas with flat terrain, safe sites for germination and establishment of common plant seeds, and carried seeds of 20 plant species; (2) the civet feces were more strongly preferred by dung beetles than raccoon dog feces; and (3) the abundance of large tunneler beetles with superior seed burial ability using the civet feces was 3.7 times as high as that of raccoon dog feces. Thus, these findings suggest that this non-native mesocarnivore could recover functional redundancy by offsetting injured endozoochorous processes.