Habitat use by platypus (Ornithorhynchus anatinus) in a modified Australian Wet Tropics catchment, north-eastern Queensland

Abstract

The habitat affiliations of platypus (Ornithorhynchus anatinus) were investigated in the upper Barron River and its tributaries, a modified Wet Tropics catchment in north-eastern Queensland, Australia. A habitat assessment was carried out at 46 sites, and a visual monitoring survey was used to determine whether platypus were present at these sites. Habitat assessment of riparian and in-stream parameters included an evaluation of factors known to influence platypus populations: disturbance level, stream depth and width, riparian continuity, the amount of overhanging vegetation, bare soil along banks, large woody debris, weeds, pool and riffle area and substrate types. Sites where platypus sightings occurred were characterised by a minimum channel width of 3.8 m and slow-flowing pools with depths of 0.49–2.0 m. These findings concur with platypus habitat preferences as described in other regions, although some in-stream and riparian factors considered as important components of platypus habitat in other studies (riparian continuity, large woody debris, undercut banks and coarse stream substrate) were not associated with the presence of platypus in this study. This study represents the first investigation of the influence of human-induced habitat modification on platypus affiliations in an Australian Wet Tropics river system.