Field observations provide an insight into the ecology of the Rusty Monitor

Abstract

A southern population of the Rusty Monitor (Varanus semiremex) is known to occur at Wild Cattle Creek, Tannum Sands, Queensland. Thorough field observations conducted on foot revealed that individuals are frequently observed active between late September and April. Five distinct adults were identified over a 300 metre length of tidal mangrove habitat. Two confirmed females had a set home range and were recorded active within the same areas during a 29-month period. Both females became gravid and laid eggs between October and December. Hollows in mangrove trees were used as refuge sites and may be occupied over time by several individuals. Crabs were the only prey items observed, in contrast to literature reports of a more varied diet. The monitors were not active swimmers, preferring to forage between tides, but using the water in-transit where necessary. Daily activity commenced early in the summer months but was delayed during autumn and spring. Activity was observed at temperatures as low as 25.5oC.  Varanus semiremex, crabfeeding, activity, home range, thermal regulation, mangrove species.