A study of dung decay and plot size for surveying feral pigs using dung counts

The effects of dung decay and plot size on counts of dung pellets of feral pigs (Sus scrofa) were investigated in south-eastern Australia. Greater understanding of both could potentially improve survey accuracy and field interpretation of dung counts by managers. Dung pellets persisted for up to 16 months, with over 50% disappearance within 2-5 months, depending on season. The long persistence suggests the need for caution in infering recent presence of feral pigs from the presence of intact pig dung. Partial correlation analysis showed the survival rate of pellets during the first month to be significantly negatively correlated with measures of temperature and rainfall in the month. There was a significant (P < 0.005) interaction of plot size, over the range 5-20 m(2), and month on the average number of pellets per square metre per month, and a significant (P < 0.01) effect of year on average counts. The largest plot size always detected at least one dung pellet but smaller plots did not.