A radiotelemetric study of movements, thermoregulation and habitat utilization of arafura filesnakes (Serpentes: Acrochordidae)

Miniature temperature-sensitive radiotransmitters were attached to 15 filesnakes (Acrochordus arafurae) in Magela Creek in tropical Australia. These snakes were monitored daily, or more often, for intervals from 2-24 days (x̄ = 14 days). Filesnakes are entirely aquatic. Habitat utilization was highly seasonal: snakes were restricted to billabongs during the dry-season but spread out into shallowly-inundated grassland at the onset of the wet-season. Telemetered snakes were relatively sedentary by day (mean displacement = 19 m), moving only to stay under the shadows of overhanging trees. This behavior may reduce avian predation. Nocturnal movements were extensive, especially during the wet-season (mean displacement = 141 m). Home ranges (0.1-4.7 ha by the uncorrected convex polygon technique) were larger than those of most previously-studied snakes, possibly because of the large body size of A. arafurae. Body temperatures of telemetered snakes averaged 26 C in the dry-season, 30 C in the wet-season, and were very similar to water temperatures. These snakes tend to be thermoconformers, but their temperatures are less variable than those of the surrounding water. Filesnakes are remarkably homoiothermic, with average body temperatures varying <2 C over a 24-h cycle during the wet-season.