A major study was started by F.R.I. in 1975 to investigate the daily and seasonal movement patterns of possums within rata/kamahi forest and their movements onto adjacent pasture land. This paper is a progress report based on 20 months of trapping records.

Nearly 1000 possums were live-trapped within a 2 square km area that varied from pasture through lowland forest into alpine scrub, in the study area at Lake Haupiri, Westland. Movement patterns vary considerably between individual animals. Nonetheless animals resident in different forest zones tend to have different movement patterns. Hence the alpine scrub animals move the least, while animals resident within 800 m of the pasture tend to move the most. The lush pasture forage draws animals from unexpectedly long distances in the forest; most of these movements appear to be via ridges. Fixed trap lines provide minimum estimates of long-distance movements and are a poor guide to the total home-ranges animals occupy. Hence these trap estimates are now being supplemented by an extensive radiotelemetry study of selected tagged possums over the entire study area.

It is already clear from trap data that possums will move several hundreds of metres to feed on pasture, and may do so quite frequently. This may place deep-forest possums at risk as potential bovine tuberculosis vectors and control programmes in tuberculosis problem areas should be reassessed accordingly.