Suchergebnisse

Context Baits are used to deliver lethal or other substances in wildlife management programs across the globe. Successful baiting campaigns are contingent upon the availability of baits to target animals. Bait density is often increased in an attempt to improve bait encounter probabilities. However, this comes with a concomitant increase in cost and may result in significant bait wastage if deployed in areas of low target species activity. Aims The aim of this study was to assess the effectiveness, efficiency and cost of different bait transect methods in intersecting home and core ranges of feral pigs as a case study to determine optimal spacing and placement of baiting transects. Methods The authors simulated a variety of systematically spaced aerial transects, watercourse-aligned aerial transects and ground transects along property boundaries and farm tracks, and compared them with home and core ranges of feral pigs, at two study sites in Queensland, Australia. Transect effectiveness at intersecting pig ranges was determined through beta-regression and estimated marginal means (emmeans); efficiency was considered as emmeans per unit of transect length. Key results The study found that systematically spaced aerial transects at 4 km intervals were the most efficient means of intersecting both home and core ranges of feral pigs. Additionally, no alternate transect method, either aerial or ground, provided significantly greater effectiveness at intersecting feral pig home and core ranges at these study sites. Ground transects along farm tracks and property boundaries were also between 113% and 192% more expensive than aerial transects at 4 km spaced intervals for either fixed-wing or rotary aircraft. Conclusion Systematically spaced aerial transects at 4 km intervals are among the most effective and are the most efficient means of intersecting feral pig ranges at the study sites examined. Implications Our methodology offers a blueprint for both vaccination and toxin baiting programs to assess and compare bait transect placements. More specifically for feral pig control, aerial transects with 4 km systematic spacing provide an effective and efficient means for intersecting feral pig ranges. Furthermore, additional data on bait encounter and interaction probabilities are required to determine transect effectiveness at bait uptake by the target species.

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.