Movements and activity patterns of arafura filesnakes (Serpentes : Acrochordidae) in tropical Australia

A four-year capture-mark-recapture study of Arafura filesnakes (Acrochordus arafurae) in the "wet-dry" Australian tropics provided information on movement patterns in this species. Based on capture rates in fyke nets set in shallow water in Magela Creek (Kakadu National Park), these snakes showed a strong lunar cycle of activity, with less movement on moonlit nights. Trap sites under overhanging vegetation consistently caught more snakes than did trap sites in open water, and juvenile snakes were caught mainly in areas covered in floating vegetation. We interpret the preference of A. arafurae to move mostly on dark nights, and to travel mostly through heavily vegetated areas, as adaptive in terms of reducing their vulnerability to predators (especially, visually hunting birds). Marked filesnakes tended to move increasingly further from their sites of initial capture as time passed, suggesting that they may be nomadic rather than having fixed home ranges. Larger snakes moved greater distances. Males were more likely to remain at their initial capture site than were females, but dispersal patterns of males and females were similar in most respects. Filesnakes sometimes moved from one billabong to another during the wet season (when the billabongs are connected by large expanses of shallow water), with most such cases involving adjacent billabongs.