Influence of dung-beetles on disappearance and decay of sika deer fecal pellets

Fecal pellet disappearance and decay experiments were conducted on Mt. Inugatake from March 1996 to January 1999. Fifty pellets were placed into 69 plots and the number of pellets remaining in the plots was counted after about 30 days. Six to 9 pitfall traps baited with fresh pellets were placed near each plot. Species and number of dung-beetles captured were recorded. The fecal pellets had been collected from captured deer and refrigerated until the trial. To compare the disappearance rate between refrigerated pellets and non-refrigerated ones, 300 fresh pellets were collected around the site in January 1997 and placed into 6 plots. There was no significant difference in disappearance rate between refrigerated pellets and non-refrigerated ones. This shows that refrigerated pellets are also useful to trace the natural process of pellet disappearance. The disappearance rates varied seasonally. Pellets disappeared rapidly from spring to autumn. Conversely, pellets lasted several months in winter. Eight species of dung-beetles were recorded. The most abundant were Phelotrupes auratus, Aphodius isaburoi, and Aphodius unifasciatus. P. auratus occurred from spring to autumn, A. isaburoi from autumn to spring, and A. unifasciatus in spring. The disappearance rate of the pellets attacked by dung-beetles was much greater than that of the pellets that were not attacked. This indicates that disappearance of the deer pellets was mainly caused by dung-beetles.