Seasonal changes and altitudinal variation in deer fecal pellet decay

Surveying dung pellet groups to estimate population size requires knowledge of the dung decay rates in different environmental conditions. We evaluated seasonal and elevational differences in the decay rates of fresh deer pellets in the Ashio–Nikko Mountains, Japan. At each of four sites (1,500, 1,200, 900, and 600 m above sea level), we set out four replicates of 50 fresh deer pellets each month from September 2008 to August 2009. Dung pellet groups were evaluated after 24 h and again monthly. We also monitored the dung beetle fauna monthly using pitfall traps. Dung beetle activity was positively correlated with temperature, and the rate of dung decay was strongly correlated with dung beetle dry weight. Decay was most rapid during summer and at lower altitudes; pellets set out during winter did not decay until the following spring. Resource managers who use dung surveys to estimate population sizes in mountainous regions should consider the decay rates at different altitudes.