Food Habits of the Taiwan Beauty Snake, Elaphe taeniura friesi, as an Introduced Species on Okinawajima Island

Abstract

The Taiwan beauty snake, Elaphe taeniura friesi, has established a stable population in the central part of Okinawajima Island, and there are concerns about the negative effects of the snakes' predation on the native fauna. Thus, we examined the stomachs of 239 E. t. friesi specimens collected on Okinawajima Island from July 2018 to November 2019. Stomach contents were identified to the species level whenever possible based on morphological observations and/or DNA analyses. Of the 239 snake specimens, 39 (12 males, 16 females, and 11 juveniles) had contents in their stomach, including 67 prey items, 75% of which were mammals (Muridae and Soricidae) and the rest of which were birds (Pycnonotidae, Cisticolidae, and Columbidae). Rattus rattus occurred most frequently; 25 of the 39 snakes examined had this species in their stomachs. All avian prey items detected were nestlings and eggs. Twelve snakes had multiple prey items in their stomach, including in most cases either nestlings of passerine birds or infants or subadults of R. rattus. Therefore, E. t. friesi is an endotherm consumer that occasionally preys on nestlings and infant rats. These food habits suggested that E. t. friesi uses various habitats, from the humus layer on the ground to the branches of trees, for foraging. Several endangered endemic rodent and bird species exist in the northern area of Okinawajima Island; thus, our results provide a warning about potential negative impact on such animals when E. t. friesi expands its range to the northern part of the island.