Factors influencing the activity ranges of feral pigs (Sus scrofa) across four sites in eastern Australia

Abstract

Context Understanding the home-range size and the ecological drivers that influence the spatial distribution of feral pigs is of paramount importance for exotic-disease modelling and the improvement of pest management programs. Aims To investigate various factors affecting home- and core-range size and test selection of habitat, to better inform disease modelling and pest management programs. Methods In this study, 59 GPS-collared feral pigs were tracked over four sites in eastern Australia between 2017 and 2021. Using minimum convex polygon (MCP) and the nearest-neighbour–local convex hull (k-LoCoH) as home-range estimators and foliage projective cover (FPC) as an estimator of landscape-scale shelter, we investigated the influence of sex, site, season, year and body weight on range size and tested selection of habitat by using chi-squared and Jacob’s index tests. Key results Home-range sizes were highly variable, with k-LoCoH90 (home) ranges between 0.08 and 54.97 km2 and k-LoCoH50 (core) ranges between 0.01 and 7.02 km2. MCP90 ranged between 0.15 and 242.30 km2, with MCP50 being between 0.07 and 60.61 km2. Sex and site both significantly (P < 0.001) influenced home-range size, but season and year did not. Home-range size was shown to increase with body mass for both sexes (P = 0.001). Importantly, the data indicated that feral pigs prefer habitat within 20–40% FPC (woodland), whereas open forests (51–80% FPC) and closed forests (>80% FPC) were actively avoided. Typically, use of open vegetation (1–10% FPC) was also avoided, but this behaviour varied and was dependent on site. Conclusion Feral pig ranges are influenced by sex, site and body mass but not by season and year. Broad-scale selection for shelter indicated that feral pigs prefer habitat between 20% and 40% FPC. Implications Targeting or avoiding such areas respectively for control or monitoring tool placement may result in improved, efficient outcomes to monitor or manage feral pig populations. Feral pig distribution modelling may also find benefit in the consideration and further study of the above factors and the influence of food and water sources on the activity ranges and behaviour of feral pigs.