Ecological Associations of Feeding Sites of Feral Pigs in the Queensland Wet Tropics

Abstract

Data from 152 plots (0·8 ha) and 659 small quadrats (0·04 ha) were used to assess rooting activity by feral pigs in forest communities in north Queensland. Study sites spanned the rainforest–sclerophyll-forest gradient along the western margin of the wet tropics region. Detailed floristic, physiognomic and edaphic data were recorded for each plot and used to develop a predictive model of pig activity in these habitats. The most striking result was that rooting activity varied markedly among different forest types. Wet sclerophyll forests consistently had the greatest area disturbed, followed by mesic and dry sclerophyll forests. Both rainforest and rainforest-invaded sclerophyll forests had relatively low activity levels. There were some differences in rooting activity among different geographic regions, but few effects of local topography, soil type or proximity to water. A mathematical model was developed to predict the ecological associations of pig rooting activity, using generalised linear modeling. Pig rooting was associated with certain attributes of wet sclerophyll forests and with slopes and ridge tops, but the model had limited effectiveness, with fitted values explaining 16% of the actual variation in rooting activity. This may have resulted because microhabitat preferences of pigs varied among different forest types and seasons. We suggest that pigs could be consuming fungal fruit-bodies in sclerophyll forests, and if so they may compete for food with some native, mycophagous mammals.