2D or not 2D? Three-dimensional home range analysis better represents space use by an arboreal mammal

For animals which utilise vertically distributed habitat resources, home ranges quantified in two-dimensions (2D) likely misrepresent space use and constrain interpretations of species' ecology and behaviour. Three-dimensional (3D) home range estimation has proved useful for understanding space use over relatively large vertical ranges (e.g. 100's of meters), yet none have applied a 3D approach to describe space use over narrower vertical ranges (e.g. meters or 10's of metres) typical for many arboreal animals. This study demonstrates 3D home range estimation for the arboreal western ringtail possum (Pseudocheirus occidentalis) using temporally resolute locations (15 min intervals) of five radio collared animals. We hypothesised that, due to the use of vertically distributed habitat resources, 3D home ranges would be more complex, spanning a range of heights, and would subsequently be larger in size compared to those estimates derived from typical 2D analysis. A comparison of 50% (core) and 95% (total) 2D kernel density and 3D kernel density utilisation distributions reveal structurally complex home ranges that span the entire vertical range of vegetated habitat. Estimates of the total 3D home range size were significantly greater than those derived from 2D analysis, and the difference in size was positively related to the vertical range of available habitat. This study establishes that 3D home range analysis can reveal information on vertical space use of arboreal species over relatively small vertical ranges, and is likely to be valuable in understanding the use and identification of key habitats and resources, as well as interactions among sympatric species.